WO2012121725A1 - Nanotubes auto-assemblés biologiquement - Google Patents

Nanotubes auto-assemblés biologiquement Download PDF

Info

Publication number
WO2012121725A1
WO2012121725A1 PCT/US2011/027831 US2011027831W WO2012121725A1 WO 2012121725 A1 WO2012121725 A1 WO 2012121725A1 US 2011027831 W US2011027831 W US 2011027831W WO 2012121725 A1 WO2012121725 A1 WO 2012121725A1
Authority
WO
WIPO (PCT)
Prior art keywords
virus
swnts
nanotubes
nanotube
nanoparticles
Prior art date
Application number
PCT/US2011/027831
Other languages
English (en)
Inventor
Xiangnan DANG
Hyunjung YI
Angela M. Belcher
Paula T. Hammond
Original Assignee
Massachusetts Institute Of Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Massachusetts Institute Of Technology filed Critical Massachusetts Institute Of Technology
Priority to PCT/US2011/027831 priority Critical patent/WO2012121725A1/fr
Publication of WO2012121725A1 publication Critical patent/WO2012121725A1/fr

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/158—Carbon nanotubes
    • C01B32/168—After-treatment
    • C01B32/174—Derivatisation; Solubilisation; Dispersion in solvents

Definitions

  • This invention relates to biologically self-assembled nanotubes, and methods of making and using them.
  • organisms can build complex inorganic micro- and nanostructures by a process termed "biomineralization.”
  • Natural biological systems have evolved diverse structures, e.g., bones, teeth, mollusk shells and magnetosomes, which exhibit greatly increased structural integrity compared to the organic scaffold from which they are formed.
  • Nature's design principles are very useful as they can provide new insights that allows engineers to create new inorganic nanomaterials via environmentally benign routes.
  • a method of making a composite material includes providing a composition including a virus with binding affinity to nanotubes, contacting the nanotubes to the virus, thereby forming a virus-nanotube complex, and contacting a plurality of nanoparticles to the virus-nanotube complex, thereby forming a virus- nanotube-nanoparticle complex.
  • the method can further include adjusting the pH of the composition to a predetermined pH, thereby dispersing the nanotubes along the virus.
  • the virus can include a template for nucleation and growth of nanoparticles.
  • the method can further include growing the nanoparticles of the virus-nanotube-nanoparticle complex.
  • the method can further include removing the virus, thereby forming a nanotube-nanoparticle complex.
  • Contacting the nanotubes to the virus can include non-covalent binding of the nanotubes to the virus.
  • the virus can be a genetically engineered virus.
  • the virus can be M13.
  • the plurality of nanoparticles can include inorganic nanoparticles.
  • the inorganic nanoparticles can include TiCh nanoparticles.
  • the nanotubes can include semiconductive nanotubes.
  • the semiconductive nanotubes can include single-walled carbon nanotubes.
  • a method of making a composite material includes providing a composition including a virus with binding affinity to carbon nanotubes, contacting the carbon nanotubes to the virus, thereby forming a virus-carbon nanotube complex, contacting a plurality of inorganic nanoparticles to the virus-carbon nanotube complex, thereby forming a virus-carbon nanotube-inorganic nanoparticle complex, growing the inorganic nanoparticles of the virus-carbon nanotube-inorganic nanoparticle complex, and removing the virus, thereby forming a carbon nanotube-inorganic nanoparticle complex.
  • a method of making a photovoltaic device includes providing a composition including a virus with binding affinity to nanotubes, contacting the nanotubes to the virus, thereby forming a virus-nanotube complex, adjusting the pH of the composition to a predetermined pH, thereby dispersing the nanotubes along the virus, contacting a plurality of nanoparticles to the virus-nanotube complex, thereby forming a virus-nanotube-nanoparticle complex, removing the virus from the virus-nanotube- nanoparticle complex, thereby forming a nanotube-nanoparticle complex; and incorporating the nanotube-nanoparticle complex into a photovoltaic device.
  • the virus can be a genetically engineered Ml 3 virus.
  • the plurality of nanoparticles can include inorganic nanoparticles.
  • the nanotubes can include semiconductive carbon nanotubes.
  • Incorporating the nanotube-nanoparticle complex into a photovoltaic device can include forming a photoanode with the nanotube-nanoparticle complex.
  • the photovoltaic device can be a dye-sensitized solar cell.
  • Removing the virus from the virus-nanotube-nanoparticle complex can include annealing in an Ar atmosphere at a temperature of at least 600 °C.
  • a photovoltaic device in another aspect, includes a photoanode including a nanocomposite, wherein the nanocomposite includes a plurality of nanotube-nanoparticle complexes.
  • the nanocomposite can be a biomineralized nanomaterial.
  • the biomineralized nanomaterial can be a virus-templated nanomaterial.
  • the virus can include Ml 3.
  • the nanotubes can include semiconductive nanotubes.
  • the nanotubes can include single- walled carbon nanotubes.
  • the nanoparticles can include inorganic nanoparticles.
  • the inorganic nanoparticles can include Ti0 2 nanoparticles.
  • FIG. la is a schematic depiction of the process of virus single-walled carbon nanotube (SWNT) complexation and biomineralization of Ti0 2 on the surface of the virus-SWNT complex.
  • SWNT virus single-walled carbon nanotube
  • FIG. lb is a schematic depiction of the scheme of dye-sensitized solar cells (DSSCs) incorporated with SWNT/Ti0 2 complex.
  • DSSCs dye-sensitized solar cells
  • FIGS lc-d are energy diagrams of DSSCs incorporated with (c) semiconducting SWNTs and (d) metallic SWNTs.
  • FIGS. 2Ai-iv are photographs depicting the characterization of virus-SWNT complexes.
  • SWNT binding viruses of which p3 are enzymatically biotinylized were complexed with SWNTs (left) and combined with streptavidin-coated magnetic beads (right) and (ii) incubated. Hi, Incubated solution is pulled out using magnet placed external to the eppendorf tube of the solution, iv, The supernatant is compared with the starting virus-SWNT solution, confirming binding of SWNT to the virus.
  • FIGS. 2b-c are HRTEM micrographs of virus-SWNT complexes. SWNTs are pointed by an arrow and the virus is indicated by dashed lines.
  • FIG. 2d is a TEM micrograph of Ti0 2 biomineralized on a virus-SWNT complex.
  • FIG. 2e is a Raman spectrum of photoanode incorporated with SWNT/Ti0 2 complex after being annealed in Ar at 600 °C. Peaks of SWNTs and peaks of anatase are also shown.
  • FIGS. 3 are graphs of (a) I-V curves, and (b) calculated electron diffusion lengths from three DSSCs: with only Ti0 2 nanoparticles; with 0.2 wt pure semiconducting SWNTs; and with 0.2 wt% pure metallice SWNTs. Virus-to-SWNT ratio of 1 :5 was used for all devices.
  • FIG. 3c is a graph showing the dependence of the power conversion efficiency and short circuit current of DSSCs on the electronic type and the concentration of SWNTs incorporated in Ti0 2 matrix. Virus-to-SWNT ratio of 1 :5 was used for all devices.
  • FIGS. 4 are PLE maps of virus-SWNT complexes with virus-to-SWNT ratios of
  • FIG. 4d is a graph showing the dependence of power conversion efficiency and short circuit current on the degree of bundling of SWNTs controlled by virus-to-SWNT ratio.
  • FIG. 5 is a graph showing the current density and power efficiency versus voltage curves of the DSSC with 0.1 wt% SWNT of 99% semiconducting component incorporated ((6,5) chirality-enriched SWNT).
  • FIG. 6 is a diagram showing the transmission line model used for fitting the electrochemical impedance data.
  • FIG. 7 is a graph showing zeta potential of the SWNT-binding virus
  • FIG. 8 is a graph showing the effect of pH-switch on complexation.
  • FIG. 9 is a diagrammatic scheme of an Ml 3 virus and its cloning vector for genetic engineering.
  • FIG. 10 are photographs showing magnetic separation of SWNTs in 2wt% SC aqueous solution.
  • FIG. 11 is a graph showing the effect of annealing condition on device performance of DSSCs. I-V curves from DSSCs with only Ti0 2 nanoparticles as photoanodes annealed at 600°C in Ar (line 1 ) and at 500°C in air (line 2) are shown.
  • FIG. 12 is a graph showing the device performance of control DSSCs.
  • Device performance of DSSCs with only Ti0 2 nanoparticles (line 1), Ti0 2 nanoparticles and virus/TiCh complex without SWNT (line 2), Ti0 2 nanoparticles with surfactant-stabilized SWNT (line 3), and Ti0 2 nanoparticles with as-produced SWNT powders (line 4).
  • FIG. 13 is a graph showing IPCE measured for various DSSCs. DSSCs with only Ti0 2 nanoparticles and with different SWNTs of various concentrations are compared.
  • FIG. 14 is a spectra showing the comparison of absorption spectra from SWNTs and N719 dye in the visible region.
  • FIG. 15 is a PL spectra of virus-SWNT complex solutions with various virus-to- SWNT ratios.
  • FIG. 16 is a Raman spectrum of photoanode with SWNT/TiC complex annealed in air at 600 °C.
  • FIG. 17 is a spectra of x-ray diffraction of photoanodes with SWNT/Ti0 2 complex annealed in Ar at 600 °C. Only anatase phase of Ti0 2 presents after annealing.
  • Nanocomposite materials can provide advantageous properties that non-composite materials cannot.
  • nanocomposites including semiconducting nanotubes and photoresponsive (e.g., absorbing or emitting) materials can be useful in a variety of applications, including medical imaging (e.g., deep tissue imaging) and optoelectronic devices, such as light emitting devices and photovoltaics, e.g., dye-sensitized solar cells, quantum dot photovoltaics, and organic photovoltaics.
  • Nanoporous solar cells are promising due to the low cost and potentially higher efficiency than silicon solar cells, enabled by high internal quantum efficiency, large surface-to- volume ratio, and a tunable absorption range. See, for example, Sambur, J. B., Novet, T. & Parkinson, B. A. Multiple exciton collection in a sensitized photovoltaic system. Science 330, 63-66 (2010); O'Regan, B. & Gratzel, M. A low-cost, high-efficiency solar cell based on dye-sensitized colloidal Ti0 2 films. Nature 353, 737-740 (1991); Kamat, P. V, Quantum dot solar cells: Semiconductor nanocrystals as light harvesters. /. Phys. Chem.
  • IPCE incident photon-to-current conversion efficiency
  • SWNTs Single- walled carbon nanotubes
  • Single wall carbon nanotube scaffolds for photoelectrochemical solar cells capture and transport of photogenerated electrons.
  • SWNTs are an ensemble of metallic and semiconducting
  • SWNTs While semiconducting SWNTs can provide an efficient electron diffusion path without recombination, metallic components provide a short-circuit path, negating any possible improvements. Moreover, the strong tendency for SWNTs to form bundles creates contact between semiconducting and metallic SWNTs, transferring electrons from semiconducting SWNTs to metallic ones. See, for example, Bonaccorso, F. Debundling and selective enrichment of SWNTs for applications in dye-sensitized solar cells. Int. J. Photoenergy 2010, 727134 (2010) and O'Connell, M. J. et al. Band gap fluorescence from individual single-walled carbon nanotubes. Science 297, 593-596 (2002), each of which is incorporated by reference in its entirety.
  • M13 virus is a filamentous bacteriophage which can be genetically engineered to express peptides having a selective binding affinity for certain materials, e.g., inorganic materials. See, for example, Whaley, S. R. et al. Selection of peptides with certain materials, e.g., inorganic materials. See, for example, Whaley, S. R. et al. Selection of peptides with certain materials, e.g., inorganic materials. See, for example, Whaley, S. R. et al. Selection of peptides with
  • Enginereed M13 bacteriophage can serve as a template for nanoparticle growth. See, for example, Ki Tae Nam, Dong-Wan Kim, P. J. Y. Science 2006, 312, 885, which is incorporated by reference in its entirety.
  • Protein engineering techniques e.g., phage display
  • the M 13 coat protein can be engineered to include a metal binding motif, which, for example, can be a negatively charged motif, e.g., tetraglutamate or a peptide with a binding affinity to a metal.
  • the motif can be a 12-amino acid peptide with a high affinity for Au.
  • engineered M13 virus particles allowed control of the assembly of nanowires of C03O4 with a small percentage of Au dopant. Id.
  • M13 bacteriophage contains about 2700 copies of a major coat protein, pVIII protein, which are longitudinally assembled along the virus's DNA.
  • the 2700 copies are stacked in units of five in a helical array.
  • minor coat proteins pill, pVI, pVII, and pIX proteins
  • This unique periodic, uniform structure is genetically controlled, and can be used to create tailor-made micro- or nanostructures.
  • the various proteins may be genetically modified to have a specific peptide motif that can bind and organize nanomaterials. Because the amino acid sequence of this motif is genetically linked to the virus DNA and contained within the virus capsid, exact genetic copies of the virus scaffold can be created easily and quickly reproduced by infection in bacterial hosts.
  • the major coat protein of M13 bacteriophage is genetically engineered to specifically bind to metal ions or nanoparticles.
  • Metal oxide nanotubes can be synthesized using this engineered virus template. Due to the anisotropic structure of bacteriophage, virus-based metal oxide nanotubes can self-assemble into a mesoporous nanocrystalline form. Furthermore, the highly oriented helical major coat proteins of M13 virus promote the structural stability of individual virus-based nanotubes, and can increase the durability of devices or components incorporating them. Additional aspects of virus-templated formation of micro- and nanostructures are described in U.S. patent application 11/254,540, the contents of which are incorporated herein by reference.
  • peptide denotes a string of at least two amino acids linked together by peptide bonds.
  • Peptide may refer to an individual peptide or a collection of peptides. Peptides may contain only natural amino acids, although non- natural amino acids (e.g., compounds that do not occur in nature but that can be incorporated into a polypeptide chain) and or amino acid analogs as are known in the art may alternatively be employed.
  • one or more of the amino acids in a peptide may be modified, for example, by the addition of a chemical entity such as a carbohydrate group, a phosphate group, a farnesyl group, an isofarnesyl group, a fatty acid group, a linker for conjugation, functionalization, or other modification, etc.
  • a chemical entity such as a carbohydrate group, a phosphate group, a farnesyl group, an isofarnesyl group, a fatty acid group, a linker for conjugation, functionalization, or other modification, etc.
  • the modifications of the peptide lead to a more stable peptide (e.g., greater half-life in vivo). These modifications may include cyclization of the peptide, the incorporation of D-amino acids, etc. None of the modifications should substantially interfere with the desired activity of the peptide.
  • Ml 3 bacteriophage can have a major coat protein with a motif that binds specific metals, the motif can also block binding of other metals.
  • tetraglutamate can interact with various metal ions but blocks interaction with Au due to electrostatic repulsion. See, for example, Ki Tae Nam, Dong-Wan Kim, P. J. Y. Science 2006, 312, 885, which is incorporated by reference in its entirety.
  • M13 bacteriophage can be engineered to bind to different materials at different sites, by introducing different affinity motifs in the major and minor coat proteins.
  • virus types which may be used for the inventive methods and compositions include, but are not limited to, tobacco mosaic virus (TMV), cowpea mosaic virus, T7 bacteriophage, T4 bacteriophage, retrovirus, adenovirus, papillomavirus, parvovirus B19, herpes simplex virus, varicella- zoster virus, cytomegalovirus, epstein-barr virus, smallpox virus, vaccinia virus, hepatitis B virus, polyoma virus, transfusion transmitted virus, enterovirus, corona virus, rhinovirus, hepatovirus, cardiovirus, aphthovirus, poliovirus, parechovirus, erbovirus, kobuvirus, teschovirus, coxsackie, reovirus, rotavirus, norwalk virus, hepatitis E virus
  • a method using a biological scaffold can be used to integrate nanotubes into photovoltaic devices for highly efficient electron collection. Importantly, this method does not significantly affect electron transfer between semiconducting nanoparticles and nanotubes nor change the pristine properties of nanotubes.
  • Nanotubes are bound along the length of the biological scaffold and dispersed.
  • the scaffold/nanotube complex scheme can include part of the surface of the bound nanotube exposed to water, enabling a direct contact between biomineralized nanoparticles.
  • biomineralized nanoparticles templated on the biological scaffold can aid the complete encapsulation of nanotubess.
  • Nanotubes can be successfully incorporated into photoanodes of photovoltaic devices. Semiconducting nanotubes can increase power conversion efficiency of photovoltaic devices through an increased electron diffusion length, and thus a higher electron collection efficiency. With the combination of debundling of nanotubes and
  • nanoparticles only enabled by the biological scaffold, it can be demonstrated that semiconducting and metallic nanotubes affect device performance in opposite ways. Furthermore, bundling of nanotubes can affect photovoltaic device performance through controlling the microstructure of scaffold/nanotube complexes.
  • a method using an Ml 3 virus as a biological template can be used to integrate SWNTs into photovoltaic devices for highly efficient electron collection. Importantly, this method does not significantly affect electron transfer between semiconducting nanoparticles and SWNTs nor change the pristine properties of SWNTs.
  • SWNTs are bound along the length of the genetically engineered Ml 3 virus and dispersed.
  • the virus- SWNT complex scheme can include part of the surface of the bound SWNT exposed to water, enabling a direct contact between biomineralized inorganic nanocrystals and SWNTs.
  • biomineralized nanocrystals templated on the virus can aid the complete encapsulation of SWNTs, which is challenging to realize with surfactant- dispersed SWNTs.
  • SWNTs can be successfully incorporated into photoanodes of dye- sensitized solar cells (DSSCs).
  • Semiconducting SWNTs can increase power conversion efficiency of photovoltaic devices through an increased electron diffusion length, and thus a higher electron collection efficiency.
  • bundling of SWNTs can affect photovoltaic device performance through controlling the microstructure of virus-SWNT complexes.
  • the loaded virus expressing one or more types of modified peptides, can be used to nucleate nanoparticles of a metal oxide.
  • Micro- or nanoparticles and/or nanotubes can be produced at room temperature, in contrast to the elevated temperatures (> 150 °C) required for some other techniques.
  • the pVffl-engineered M13 virus is incubated with a metal salt precursor, for example, cobalt chloride, at a concentration between about 1 mM and about 5 mM.
  • Metal ions in solution are chelated by carboxylic acid groups on the pVIII proteins.
  • Chelated metal ions are then oxidized by adding a basic solution such as sodium hydroxide (NaOH), at, for example, between about 10 mM and about 100 mM.
  • a basic solution such as sodium hydroxide (NaOH)
  • metallic nanoparticles can be nucleated and grown on the virus major coat proteins by adding between about 5 mM and about 10 mM of a reducing agent such as sodium borohydnde (NaBK or hydrazine (N 2 H 2 ) to a metal salt solution in which microgels are suspended.
  • a reducing agent such as sodium borohydnde (NaBK or hydrazine (N 2 H 2 )
  • the virus can be fully coated with nanoparticles, forming a metallic nanotube.
  • the metallic nanotube is easily oxidized in an aqueous solution or in air to produce a nanotube composed of metal oxide nanoparticles, e.g., crystalline metal oxide nanoparticles.
  • the virus scaffold can be removed from the nanotubes, for example, using enzymes or solvents that disrupt or lyse the viral proteins without disturbing the ceramic phase.
  • the production conditions can be altered to modify the synthesized nanostructure.
  • the size of the nanoparticles can vary with temperature. Smaller particles may be produced at lower temperatures while larger particles may be produced at higher temperatures.
  • the viral system is stable from about 4 °C to about 80 °C; other templates, e.g., peptides, nucleic acids, etc., may be stable in similar, overlapping, or different temperature ranges.
  • Particles may range in diameter from about 2 nm across to about a micron across, for example, between 2 nm and 100 nm, between 100 nm and 500 hm, or between 500 nm and 1000 nm.
  • metal oxides such as Mn 2 0 or ⁇ 2 0 5
  • Other metal oxides can be formed into micro- or nanostructures using the techniques described above.
  • Other metals that can be used to produce micro- or nanoparticles, or nanotubes include transition metals, such as, for example, nickel, iron, cadmium, tungsten, chromium, zirconium, titanium, scandium, yttrium, copper, and others.
  • non-transition metal oxides may be formed into micro- or nanostructures.
  • Exemplary non-transition metals that can be used include but are not limited to calcium, aluminum, barium, beryllium, magnesium, and strontium.
  • All of these may be produced using the same engineered viruses, or biopanning may be employed to identify peptides that are even more selective for the particular metal or metal oxide.
  • mixed metal oxides may be produced by incubating engineered phage in solutions including salts of more than one metal.
  • Raw nanotubes manufactured by either high-pressure carbon monoxide (HiPco) or cobalt/molybdenum oxide catalysis (CoMoCAT) processes were obtained from HiPco.
  • HiPco high-pressure carbon monoxide
  • CoMoCAT cobalt/molybdenum oxide catalysis
  • SWNTs-MTM metallic SWNTs
  • IsoNanotubes-STM semiconducting SWNTs
  • a density gradient was made using a non-ionic medium, iodixanol (OptiPrep, 60 w/v% iodixanol, Sigma-Aldrich). The concentration of initial gradient was adjusted to be 15, 20, 25 30 w/v% with a volume of 6 ml, and was positioned on top of 60 w/v% stop layer solution with a volume of 3 ml.
  • 1 :4 SDS:SC.
  • 4 ml of 1:4 SDS:SC SWNT solution was added on the top of the gradient, and was centrifuged at 22°C and 32,000 rpm for 12 hours.
  • the resulting gradient was fractionated at every 250 ul after centrifugation using a fraction recovery system (Beckman Coulter), and characterized by UV-vis-nIR absorption spectroscopy and fluorescence. Fractions enriched in the (6,5) nanotube species were collected and dialyzed against 2wt% SC aqueous solution.
  • SWNT-binding virus solution was mixed with the calculated volume of SWNT dispersed by 2 wt% sodium cholate (SC) in water.
  • a dialysis membrane, MWCO of 12,000-14,000 (SpectraLabs.com) was used for all dialysis procedure.
  • the Ti0 2 biomineralization was completed using an alkoxide precursor.
  • 50 nL of titanium n-butoxide (sigma Aldrich) was dissolved in 30 mL ethanol and the solution was stirred at -20°C.
  • 10 mL aqueous solution of each different virus-SWNT complex which was pre -cooled at 4°C, was poured into the ethanol solution under vigorously stirring (about 700 rpm).
  • the final solution typically consists of 25% of water and 75% of ethanol.
  • the SWNT/Ti0 2 weight ratio is about 1/100 for virus-to- SWNT 1 :5 sample, and the template/Ti0 2 ratio was fixed when virus-to-SWNT ratio was changed to 1 :2.5 or 1 : 10. After one hour of stirring, the precipitates were centrifuged at 3000 rpm and washed with 2 times ethanol and 2 times water, then dried in vacuum oven at room temperature overnight. The yield of biomineralized Ti0 2 was higher than 90%. The templated nanowire morphology was observed using Transmission Electron
  • the FTO glass plates were immersed into a 40 mM aqueous T1CI4 solution at 80 °C for 30 min and washed with water and ethanol.
  • a layer of paste was coated on the FTO glass plates by doctor blading, left for 3 min to reduce the surface irregularity of the paste and then dried for 5 min at 120 °C. Then the film was annealed at 500 °C for 10 min.
  • This doctor blading procedure with paste was repeated to get an appropriate thickness about 13 Mm for the photoanodes.
  • the T1O2 film is treated with 40 mM TiC solution at 80 °C for 30 min again, rinsed with water and ethanol and then sintered at 500 °C for 30 min. After cooling down to 80 °C, the Ti0 2 electrode was immersed into a 0.5 mM N719 dye (Solaronix) in a mixture of acetonitrile and tert-butyl alcohol (volume ratio, 1 :1) and kept at room temperature for 24 hours.
  • the photoanodes incorporated with virus-SWNT complex were fabricated with modifications as following.
  • Various amounts of SWNT Ti0 2 complexes obtained by grinding thoroughly with a mortar and a pestle after biomineralization) were mixed with Ti0 2 paste, stirred and sonicated repeatedly.
  • Ethanol and water were removed by rotary-evaporator.
  • the photoanodes were annealed at 600 °C in Ar gas to protect SWNTs from burning.
  • the counter electrode was a layer of platinum about 100 nm thick sputtered on ⁇ substrate (Delta Technologies).
  • the electrolyte was a solution of 0.6 M l -butyl-3-methylimidazolium iodide (Sigma Aldrich), 0.03 M I 2 (Sigma Aldrich), 0.10 M guanidinium thiocyanate (Sigma Aldrich) and 0.5 M 4-tert-butyl pyridine (Sigma Aldrich) in a mixture of acetonitrile and valeronitrile (volume ratio, 85: 15).
  • the dye- adsorbed Ti(1 ⁇ 2 or SWNT/T1O 2 photoanodes and Pt counter electrodes were assembled into a sandwich type cell and sealed with a hot-melt Surlyn sealing film of 25 ⁇ thickness (Solaronix).
  • the size of the Ti0 2 electrodes used was 0.16 cm 2 (4 mmx4 mm).
  • the aperture of the Surlyn frame was larger than that of the Ti0 2 area by 2 mm.
  • Copper tape was adhered on the edge of the FTO outside of the cell. The position of the tape was 1 mm away from the edge of the Surlyn gasket and 4 mm away from the edge of the Ti0 2 layer.
  • Photovoltaic measurements were performed using an AM 1.5 solar simulator (Photo Emission Tech.).
  • the power of the simulated light was calibrated to 100 mW/cm 2 by using a reference Si photodiode with a powermeter (1835-C, Newport) and a reference Si solar cell in order to reduce the mismatch between the simulated light and AM 1.5 (AM 1.5 stands for air mass 1.5, meaning the solar simulator used to characterize the solar cells corresponded to sunlight travelling through 1.5 atmospheres, corresponding to a solar zenith angle of 48.2°.
  • AM 1.5 is the most used condition for characterizing power- generating panels).
  • I-V curves were obtained by applying an external bias to the cell and measuring the generated photocurrent with a Keithley model 2400 digital source meter. The voltage step and delay time of photocurrent were 10 mV and 40 ms, respectively.
  • Electrochemical impedance spectra of DSSCs were measured using a Solartron 1260 frequency response analyzer. The obtained impedance spectra were fitted with the Z-view software (v3.2b, Scribner Associates Inc.). The spectra were measured at various forward bias voltages (from -0.85 to -0.45 V) in the frequency range of 0.1 Hz ⁇ l MHz with oscillation potential amplitudes of 10 mV at room temperature.
  • the photoanode was connected to the working electrode.
  • the Pt electrode was connected to the auxiliary electrode and the reference electrode.
  • the impedance measurements were carried out in dark conditions.
  • the transmission line model is used for fitting the electrochemical impedance data.
  • Figure 6 shows the transmission line model is used for fitting the electrochemical impedance data.
  • R s Ohmic series resistance of the cell.
  • Rco and Ceo Contact resistance and capacitance at the interface between the conducting substrate and the Ti0 2 photoanode film.
  • R S u and Csu Charge transfer resistance and double layer capacitance at the substrate/electrolyte interface.
  • RR and CR Charge transfer resistance and double layer capacitance at the counter electrode- electrolyte interface.
  • ⁇ TM transmission line impedance of the Ti0 2 photoanode film consisting of the elements ⁇ (resistivity of electron transport in the photoanode film), TREC (charge recombination resistance at the TiCydye/electrolyte interface), and c M (chemical capacitance of the photoanode film).
  • Zeiectroiyte mass transport impedance at the counter electrode.
  • FIG. 1 illustrates the synthesis of virus-templated SW T/Ti0 2 nanocomposites.
  • a pVIII library was constructed and viruses with binding affinity toward SWNTs were identified through a bio-panning method. See, for example, Lee, S.-K., Yun, D. S. & Belcher, A. M. Cobalt ion mediated self-assembly of genetically engineered
  • SWNTs were prepared in a form of thin films on glass substrates to maximize the direct contact of the virus to SWNT and a constructed pVIII phage-display library was used.
  • Bound phage were eluted by 100 ⁇ of 0.2 M Glycine-HCl, pH 2.2 and/or mid-log E.coli culture to harvest strongly bound virus not eluted by acid solution.
  • the eluted phage were amplified and the same procedures were repeated for further rounds with increasing detergent concentration. After each round of panning, the numbers of eluted and amplified phage (counted as PFU) were measured using agar plates containing X-gal/isopropyl ⁇ -D-l -thiogalactopyranoside (IPTG)/tetracycline to set the input number of phage for each round the same. Also, plaques from each round were amplified and DNA sequenced. DNA sequencing was done at MIT Biopolymers lab.
  • M13SK derived from a commercially available M13KE vector (New England Biolabs. Inc.), was used for pVIII library construction. See, for example, Lee, S.-K., et al., Cobalt ion mediated self-assembly of genetically engineered bacteriophage for biomimetic Co-Pt hybrid material. Biomacromolecules 7, 14-17 (2005), which is incorporated by reference in its entirety.
  • Library oligonucleotide purchased from IDT (idtdna.com) was designed to fuse a randomized 8-mer peptide sequence onto pVIII, and included digestion enzyme recognition sites for BamH I and Pst I.
  • the primer and random oligonucleotides were annealed and extended to make complementary sequence of the random sequence.
  • the extended DNA duplexes were double digested with BamHI and Pstl and purified using polyacrylamide gel electrophoresis.
  • M13SK vector was double-digested using Pstl and BamHI and dephosphorylated using Antarctic phosphatase.
  • Dephosphorylated vector was ligated with double cut-DNA duplex at 16 °C overnight and purified and concentrated. (All enzymes were purchased from New England Biolabs. Inc.) 1 ⁇ of concentrated ligated vector was electrotransformed into XL-1 blue, electro-competent cells at 1.8 kV/cm and total 10 transformations were used for library construction.
  • a specific virus with the pVIII insert sequence of DSPHTELP was selected for SWNT binding and complexation for two reasons.
  • histidine H
  • the p a of the side chain of histidine is around 6 and therefore histidine in the selected sequence may allow the surface of the virus to be charge-neutralized without disrupting the virus stability.
  • SWNTs dispersed by sodium cholate surfactants are initially negatively charged due to the cholate ions non- covalently adsorbed on the SWNTs and the virus is also negatively charged at the pH of D.I. water, (i.e., pH 6). Therefore the overall interaction between the virus and SWNT during the surfactant exchange is determined by competition between binding affinity and electrostatic repulsion. See, for example, Barone, P. W., et al., Near-infrared optical sensors based on single-walled carbon nanotubes. Nature Mater. 4, 86-92 (2005), which is incorporated by reference in its entirety.
  • the pH of the dialyzing solution was set to the pi of the virus, 5.3 ( Figure 7). After the complexation was completed, the pH of the complex solution was increased to around 10, at which point the zeta potential of the virus becomes around -35 mV. This increased negative surface charge of the virus is advantageous for the colloidal stability of the complexes as well as for the nucleation of Ti0 2 on the complex template. See, for example, Hiemenz, P. C. & Rajagopalan, R. Principles of Colloid and Surface Chemistry. (Marcel Dekker, New York, 1997), which is incorporated by reference in its entirety.
  • the zeta potential was measured as follows.
  • the concentration of virus (phage) solution used was 10 12 /ml in water with 10 mM NaCl.
  • the stock solution of virus ( ⁇ 10 14 /ml) was initially dissolved in 10 mM Tris, 15 mM NaCl before diluting in 10 mM NaCl in ddHiO.
  • the solution amount used to generate curve was 30 ml.
  • the ionic concentration of the solution was as set to 10 mM NaCl for all samples to minimize the fluctuation of ionic strength during pH adjustment.
  • the pH was then adjusted using 0.1 M NaOH until the pH was around 10.
  • Electrophoretic mobility was calculated using the Smoluchowski approximation (used for particles larger than 0.2 ujn in 1 mM or greater salt solution). pH was then adjusted with 0.1 M HC1.
  • the pH of the dialyzing solution was set as 5.3 (pi of the virus) and then increased to 10 after the complexation. In contrast, for the complexes without pH switch , the pH of the dialyzing solution was kept at 10 during and after the complexation.
  • the virus-to-SWNT ratio was 1 :1 for both complexes and CoMoCAT SWNTs were used for the complexation.
  • the concentration of CoMoCAT was calculated using the equation, Hg/ml. See, for example, Zheng, M. & Diner, B. A. Solution redox chemistry of carbon nanotubes. J. Am. Chem. Soc. 126, 15490-15494 (2004); which is incorporated by reference in its entirety.
  • an empirical equation, A632@ was used for Hipco.
  • the starting concentration was 10 ug/ml (Nanolntegris).
  • a value of 1 ug of SWNT 1.06 x 10 12 was used, assuming 0.8 nm in diameter and 500 nm in length.
  • the actual number of SWNTs can be different for various SWNTs.
  • the mean lengths of the used SWNTs were similar to or longer than 500 nm but still shorter than 1 ⁇ , and therefore the calculated number of SWNT could be overestimated; but by no more than a factor of 2. Accordingly, the actual virus-to- SWNT ratio of 1 :5 could be less than that, but not higher than 1 :2.5.
  • the device performance of the SWNT-DSSCs was not sensitive in the virus-to- SWNT ratios from 1:2.5 to 1:5, the effect of electronic type of SWNTs on device performance was still valid.
  • the effect of the bundling since the same SWNTs were used for the complexation, the discussion was also valid.
  • SWNTs stabilized by the virus through this approach retained about 82% of the integrated PL intensity of the starting SWNT solution (Figure 15). Since metallic SWNTs in small bundles of SWNTs quench PL, higher PL intensity implied better dispersion of SWNTs. See, for example, O'Connell, M. J. et al. Band gap fluorescence from individual single-walled carbon nanotubes. Science 297, 593-596 (2002), which is incorporated by reference in its entirety. Therefore it can be concluded that the virus with the selected peptide sequence allowed for efficient binding and dispersion of SWNTs through pH-dependent control.
  • GLNDIFEAQKIEWHE identified through phage-display technique, was engineered onto ⁇ of SWNT-binding virus.
  • the cloning vector was extracted from SWNT binding virus using standard miniprep kit (QIAGEN). The extracted vector was digested with Eag I and Acc65 I enzymes and dephosphorylated and agarose-gel purified. Purified vector and DNA duplex were ligated using T4 DNA ligase at 16°C overnight and electrotransformed to electrocompetent XL-1 blue cells.
  • Transformed cells were incubated for 1 hr and plated and incubated at 37 °C overnight. Blue plaques were amplified and DNA sequenced to confirm the insertion of oligonucleotides to express BAP on pill.
  • Biotinylated SWNT-binding viruses were complexed with S WNTs and incubated with streptavidin-coated magnetic beads. After incubation, the magnetic beads were pulled out of the solution and the remaining solution was compared with the initial virus- SWNT solution ( Figure 2a). The remaining solution was clear whereas nonspecific binding of SWNT onto the streptavidin-coated magnetic beads in a control sample was negligible (Figure 10), implying the successful binding of SWNT on the virus.
  • HRTEM was used ( Figure 2b,c). Part of the virus was intentionally burned off during imaging in order to clearly identify the bound SWNTs. Because part of the surface of the bound SWNTs is exposed to water, biomineralized nanocrystals on the virus can make a direct contact with SWNTs.
  • nucleation of Ti0 2 on the virus-SWNT template was optimized (typical SWNT-to-Ti0 2 weight ratio is 1:100). Due to the fast hydrolysis of titanium alkoxide, homogeneous nucleation of Ti0 2 dominates in aqueous solution at room temperature. See, for example, Chen, X., & Mao, S. S., Titanium dioxide nanomaterials: synthesis, properties, modifications, and applications. Chem. Rev.. 107, 2891-2959 (2007), which is incorporated by reference in its entirety. To suppress homogeneous nucleation, Ti0 2 was nucleated on the virus-SWNT template at lowered temperature (-20 °C) and in 75% ethanol solution.
  • this virus enabled self-assembly method can have several advantages. See, for example,
  • SWNTs were bound and stabilized by the virus through non-covalent binding and therefore no chemical modification of the SWNTs was needed, thus preserving the high electron mobility in the SWNTs.
  • the partially exposed surface of SWNT in the virus-SWNT complex enabled direct contact between SWNTs and Ti0 2 . This can be important for electron transfer at the interface of SWNT/Ti0 2 .
  • an excess of virus was not required to disperse SWNTs.
  • Surfactants needed to be at a higher concentration than critical micelle concentration (CMC), typically ten to a hundred times more than the virus used for stabilizing SWNTs. The free surfactants made heterogeneous nucleation of Ti0 2 on the surface of SWNTs difficult.
  • CMC critical micelle concentration
  • SWNT Ti0 2 nanocomposites were mixed with Ti0 2 nanoparticles (SWNT concentration in Ti0 2 matrix varies from 0 to 0.2 wt%) and fabricated for DSSCs using the same method, except that the devices were annealed in an Ar atmosphere (instead of air) to protect SWNTs and elevated temperature (600 °C instead of 500 °C) to remove viruses and polymers.
  • Control devices with only Ti0 nanoparticles annealed at two different annealing conditions showed similar overall power conversion efficiencies, confirming the different annealing conditions used in this study did not affect the power conversion efficiency of DSSCs (Figure 11).
  • Figure lb shows device structures and
  • Ti0 2 nanoparticles accept electrons from photo-excited dyes, and these electrons are transferred to the conduction band of SWNTs after diffusion among Ti0 2 nanoparticles. Then, SWNTs transport the electrons quickly to the current collector (fluorine doped tin oxide, FTO) to prevent back-electron transfer and recombination.
  • FTO fluorine doped tin oxide
  • I-V curves show the photovoltaic performance of DSSCs with different electronic types of SWNTs incorporated into photoanodes.
  • the electron collection efficiency (decided by electron diffusion length) should fit to the difference of the power conversion efficiency.
  • the calculated ratio of electron collection efficiency for semiconducting SWNTs incorporated DSSCs, DSSCs with only Ti0 2 nanoparticles, and metallic SWNTs incorporated DSSCs is 1 :0.93:0.54, and the measured power conversion efficiency ratio is 1 :0.79:0.63.
  • the order of magnitude differences in extrapolated diffusion length accounted for the difference in power conversion efficiency.
  • metallic SWNTs (Figure Id) have a continuous band structure and therefore electrons transferred from Ti0 2 can stay at a continuous energy level near the Fermi level, which accelerates recombination of electrons to the dye or back reaction to tri-iodide in the electrolyte.
  • the dye absorbs photons and generates electron-hole pairs, and then instant charge separation occurs at the dye Ti0 2 interface preventing back electron transfer and charge recombination.
  • virus-SWNT template for synthesizing the SWNT/Ti0 2 complexes and incorporating them into DSSCs was demonstrated by following control experiments.
  • DSSCs with viruses but without SWNTs were shown to have similar device performance to the devices made with only Ti0 2 nanoparticles ( Figure 12).
  • This control experiment showed that the viruses did not participate in the photoelectrochemical processes (it is worth noting that here the template was only about 10% mass of the total Ti0 2 ) and one-dimensional morphology of Ti0 2 templated on the virus did not affect the performance of the device significantly.
  • viruses bound SWNTs prevented SWNTs from bundling, and acted as templates for assembling and synthesizing
  • SWNT Ti0 2 core-shell nanocomposites by heterogeneous nucleation Another control experiment using surfactant-stabilized SWNTs showed lower device efficiency (Figure 12). Free surfactants in solution favored homogeneous nucleation as opposed to the heterogeneous nucleation for the encapsulation of SWNTs in Ti0 2 when using virus- stabilized SWNTs. Homogeneous nucleation of Ti0 2 resulted in SWNTs with exposed surfaces (bundles of SWNTs appeared after synthesis), increasing electron recombination and back reaction in DSSCs. Additionally, more surfactants than viruses were used to stabilize SWNTs, resulting in more impurities in the devices.
  • IPCE spectra were measured with a commercial IPCE measurement system (Model QEX7, PV Measurements, Inc.). Under full computer control, light from a xenon arc lamp was focused through a grating monochromator equipped with two 1200 grating lines/mm diffraction gratings onto the photovoltaic cell under test.
  • the monochromator was incremented through the visible spectrum (from 350 nm to 750 nm) to generate the spectral response of IPCE with a spectral resolution of 10 nm.
  • the incident photon flux was determined using a calibrated silicon photodiode (calibrated by PV Measurements, Inc.). Measurements were performed in a short-circuit condition while the cell was under background illumination from a bias light of 50 mW/cm 2 . Bias illumination was from the same direction as the monochromatic light, which was from the FTO side.
  • the monochromatic beam was chopped using a computer controlled shutter at a frequency of 4 Hz and averaging of up to 40 shutter cycles was employed.
  • the maximal absorption wavelength of metallic SWNTs in the visible region was around 700 nm, which did not overlap with the absorption peaks of N719 dye.
  • the maximal absorption wavelength of semiconducting SWNTs in the visible region was around 500 nm and this range overlapped with the absorption peak of N719 dye ( Figure 14).
  • the concentrations of measured solutions were not scaled with the final concentration used in the DSSCs to show the spectral difference more effectively.
  • the concentration of semiconducting and metallic SWNTs aqueous solution was 10 ⁇ g/mL, and the concentration of N719 dye in the solution of acentonitrile/tert-butyl alcohol (volume ratio 1 :1) was 5xl0 '5 M. If the optical loss from semiconducting SWNTs affected the device performance, then the spectral response of IPCE around 500 nm would decrease with increasing concentrations of semiconducting SWNTs. However, EPCE for semiconducting SWNTs incorporated devices did not show significant difference around 500 nm. This indicated that optical loss from semiconducting SWNTs was not severe and did not affect the spectral shape of IPCE. The optical loss from low concentrations of SWNTs may not have contributed to the device performance significantly, and the different device performances might have arisen from different electron collection efficiencies.
  • the mass/volume concentration for 0.1 wt% SWNTs in Ti0 2 is about 200 ⁇ cm 3 considering that the density of Ti0 2 is about 4 g/cm 3 and the porosity of Ti0 2 film is estimated as 0.5.
  • PL from SWNTs was measured with a home- built near-infrared (NIR) PL microscope.
  • NIR near-infrared
  • An inverted microscope was coupled to a Princeton Instruments OMA V ID InGaAs array detector through a PI Acton SP2500 spectrometer.
  • excitation sources a 785 nm laser and a Xe lamp coupled to a monochromator were used for PL spectra and PLE mapping, respectively.
  • a general and programmable method can include using a genetically engineered virus to template compact core-shell SWNT/nanocrystals nanocomposites.
  • SWNTs can be stabilized without surfactants or surface modifications and their electronic properties0 can be preserved.
  • well-dispersed semiconducting SWNTs can improve the power conversion efficiency of DSSCs up to a value of 10.6%.
  • Metallic and semiconducting SWNTs can affect the device performance in the opposite way. Aggregation states of SWNTs can affect the device performance, leading to further studies incorporating SWNTs in photovoltaic devices more effectively.5 Because SWN ⁇ s have good thermal conductivity in addition to high electron mobility, this approach might improve the stability of large DSSC modules.
  • the route to DSSC improvement lies in the development of dyes with absorption extending into the infrared and better redox couples which allow for higher voltages
  • the approach described herein can facilitate the utilization of SWNTs in many practical photovoltaic devices that require efficient electronic diffusion and reduced electron recombination, for instance, quantum dot solar cells, organic solar cells, and
  • photoelectrochemical cells See, for example, Mora-Sero, I. & Bisquert, J.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Nanotechnology (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Hybrid Cells (AREA)

Abstract

L'invention concerne un procédé d'une approche biologique générale permettant de synthétiser des nanotubes compacts d'un modèle biologique.
PCT/US2011/027831 2011-03-10 2011-03-10 Nanotubes auto-assemblés biologiquement WO2012121725A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US2011/027831 WO2012121725A1 (fr) 2011-03-10 2011-03-10 Nanotubes auto-assemblés biologiquement

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US2011/027831 WO2012121725A1 (fr) 2011-03-10 2011-03-10 Nanotubes auto-assemblés biologiquement

Publications (1)

Publication Number Publication Date
WO2012121725A1 true WO2012121725A1 (fr) 2012-09-13

Family

ID=46798491

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2011/027831 WO2012121725A1 (fr) 2011-03-10 2011-03-10 Nanotubes auto-assemblés biologiquement

Country Status (1)

Country Link
WO (1) WO2012121725A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030113714A1 (en) * 2001-09-28 2003-06-19 Belcher Angela M. Biological control of nanoparticles
US20050221083A1 (en) * 2004-01-05 2005-10-06 University Of Texas, Massachusetts Institute Technology Inorganic nanowires
US20060137741A1 (en) * 2004-12-27 2006-06-29 Samsung Electronics Co., Ltd. Photoanode using carbon nanotubes, method of manufacturing the photoanode, and photovoltaic solar cell including the photoanode
US20070051941A1 (en) * 2003-08-14 2007-03-08 Sony Deutschland Gmbh Carbon nanotubes based solar cells
US20070285843A1 (en) * 2006-06-12 2007-12-13 Tran Bao Q NANO-electronics

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030113714A1 (en) * 2001-09-28 2003-06-19 Belcher Angela M. Biological control of nanoparticles
US20070051941A1 (en) * 2003-08-14 2007-03-08 Sony Deutschland Gmbh Carbon nanotubes based solar cells
US20050221083A1 (en) * 2004-01-05 2005-10-06 University Of Texas, Massachusetts Institute Technology Inorganic nanowires
US20060137741A1 (en) * 2004-12-27 2006-06-29 Samsung Electronics Co., Ltd. Photoanode using carbon nanotubes, method of manufacturing the photoanode, and photovoltaic solar cell including the photoanode
US20070285843A1 (en) * 2006-06-12 2007-12-13 Tran Bao Q NANO-electronics

Similar Documents

Publication Publication Date Title
US9082554B2 (en) Biologically self-assembled nanotubes
Dang et al. Virus-templated self-assembled single-walled carbon nanotubes for highly efficient electron collection in photovoltaic devices
Peng et al. Tuning the properties of luminescent nitrogen-doped carbon dots by reaction precursors
Dao et al. Facile synthesis of carbon dot-Au nanoraspberries and their application as high-performance counter electrodes in quantum dot-sensitized solar cells
Kislyuk et al. Nanorods and nanotubes for solar cells
Du et al. Dye-sensitized solar cells based on anatase TiO2/multi-walled carbon nanotubes composite nanofibers photoanode
Moore et al. Applications of carbon nanomaterials in perovskite solar cells for solar energy conversion
Huo et al. A transparent cobalt sulfide/reduced graphene oxide nanostructure counter electrode for high efficient dye-sensitized solar cells
Rattanavoravipa et al. Photovoltaic performance of hybrid solar cell with TiO2 nanotubes arrays fabricated through liquid deposition using ZnO template
Zhang et al. Bioinspired synthesis of Ag@ TiO 2 plasmonic nanocomposites to enhance the light harvesting of dye-sensitized solar cells
Liao et al. Effect of seed layer on the growth of rutile TiO2 nanorod arrays and their performance in dye-sensitized solar cells
Zhang et al. One-step synthesized CuS and MWCNTs composite as a highly efficient counter electrode for quantum dot sensitized solar cells
Zheng et al. In situ hydrothermal growth of hierarchical ZnO nanourchin for high-efficiency dye-sensitized solar cells
Mehmood et al. Nanocomposites of carbon allotropes with TiO2 as effective photoanodes for efficient dye-sensitized solar cells
Khadtare et al. Effect of oxygen plasma treatment on performance of ZnO based dye sensitized solar cells
Song et al. Efficiency enhancement of dye-sensitized solar cells by optimization of electrospun ZnO nanowire/nanoparticle hybrid photoanode and combined modification
Sun et al. Electrocatalytic porous nanocomposite of graphite nanoplatelets anchored with exfoliated activated carbon filler as counter electrode for dye sensitized solar cells
Chen et al. CdS sensitized TiO2 nanorod arrays based solar cells prepared with polymer-assisted layer-by-layer adsorption and reaction method
Hong et al. Fabrication of TiO2 nanoparticle/TiO2 microcone array photoanode for fiber-type dye-sensitized solar cells: Effect of acid concentration on morphology of microcone
Lee et al. Effect of graphene incorporation in carbon nanofiber decorated with TiO 2 for photoanode applications
Oladipo et al. Ternary Ni0. 5Zn0. 5Fe2O4/carbon nanocomposite as counter electrode for natural dye-sensitized solar cells: Electro-photovoltaic characterizations
Sharma et al. A quasi solid state dye sensitized solar cell based on gelatin/multiwalled carbon nanotube gel electrolyte and ZnO nanorod photoanode
Inoue et al. Thermo-stable carbon nanotube-TiO2 nanocompsite as electron highways in dye-sensitized solar cell produced by bio-nano-process
Sahito et al. Graphene nanosheets as counter electrode with phenoxazine dye for efficient dye sensitized solar cell
He et al. A dye-sensitized solar cells with an efficiency of 10.01% based on the MoP/MoNiP2@ Ti3C2 composite counter electrode

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 11860317

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 11860317

Country of ref document: EP

Kind code of ref document: A1