CN107328754B - Photoelectric synergistic surface plasmon-exciton catalytic reaction device and preparation method thereof - Google Patents

Abstract

The invention provides a photoelectric synergistic surface plasmon-exciton catalytic reaction device and a preparation method thereof, and belongs to the technical field of surface catalytic reaction devices. Firstly, thermally evaporating noble metal nano particles on a silicon slice of silicon dioxide/monocrystalline silicon, transferring a two-dimensional semiconductor material onto a noble metal nano particle substrate, and sequentially evaporating gold/chromium nano particles onto a two-dimensional semiconductor material and metal nano particle composite substrate as a source electrode/drain electrode in a thermal evaporation mode according to a chromium-first-and-gold-last sequence, wherein the sizes and gaps of the two electrodes are controllable; and finally, introducing a gate voltage at the bottom of the device by using the base. When the method is used for specifically manufacturing a device, the size of the shelter is convenient to control, so that the size of a gap between the source electrode and the drain electrode is controllable, gaps with different sizes can be designed according to the requirements of specific experiments, the available area of molecular reaction is improved, the local surface plasmon resonance effect is further improved, and the efficiency of surface catalysis reaction is improved.

Description

Optoelectronic synergistic surface plasmon-exciton catalytic reaction device and preparation method

technical field

The invention relates to the technical field of surface catalytic reaction devices, in particular to a photoelectric cooperative surface plasmon-exciton catalytic reaction device and a preparation method.

Background technique

Surface plasmons (SPs) are resonant excitation elements formed by coherent coupling of electromagnetic waves (light) and quasi-free electron gas collective oscillations in the surface of metals (or doped semiconductors). The electronic oscillation that can be localized on the surface of metal nanoparticles is usually called localized surface plasmon resonance (LSPR). In the nanoscale range, plasmon-induced catalytic reactions dominate, and we usually call it plasmon-induced chemical reactions. It is well known that hot electrons generated by plasmon decay play an important role in plasmon-induced chemical reactions. When the hot electrons are temporarily adsorbed on the target molecule, the neutral potential energy surface (PES) of the molecule in the plasmon-induced chemical reaction is injected with electrons, so that the reaction barrier of the molecule is significantly lowered, and the hot electrons can also temporarily act The role of linker molecules. At the same time, the kinetic energy of hot electrons can be effectively transferred to target molecules to provide energy for catalytic reactions; hot electrons can also be used as the energy required for catalytic reactions to promote molecular reactions.

However, as can be seen from the data in Document 1 (Langmuir, 2011; 27[17]:10677), the hot electrons generated by plasmon decay have very low density of states and short lifetimes, so plasmon-induced surface catalysis The efficiency of the reaction is relatively low. In order to overcome these shortcomings, the emergence of surface plasmon-exciton coupling interaction provides a new idea, because of the existence of excitons, the hot electrons generated by the coupling system are easier to accumulate, and their lifetime is compared with only plasmon The time has been greatly improved, from femtoseconds to picoseconds. On the other hand, the local surface plasmon resonance effect can greatly enhance the local electromagnetic field, which can further promote the generation of excitons and increase the efficiency of catalytic reactions. All in all, the efficiency of plasmon-exciton coupling co-driven surface catalytic reactions is much higher than that induced by surface plasmons alone.

But today's common method of introducing excitons is mainly through light induction. As reported in literature 2 (Materials Today Energy, 2017; 5:72), through the interaction of laser and two-dimensional semiconductor materials, light-induced excitons are coupled with plasmons to drive surface catalytic reactions.

The design of common electrical devices involved in it is mainly limited to the micro-nano size, as reported in Document 3 (Nature, 2008; 451:163), the observable range is small, the processing is difficult, and the cost is high. It is difficult to precisely locate it with the Raman scattering spectroscopy instrument used.

Contents of the invention

The technical problem to be solved in the present invention is to provide a photoelectric synergistic surface plasmon-exciton catalytic reaction device and a preparation method, so that the electric field is introduced while the optical field regulates the surface plasmon-exciton coupling catalytic reaction, And device design can be improved so that catalytic reactions can be performed more cheaply and efficiently.

The device includes a silicon wafer, a two-dimensional semiconductor material and a source/drain, the silicon wafer is covered with noble metal nanoparticles, the noble metal nanoparticles are covered with a two-dimensional semiconductor material, the source/drain is located on the two-dimensional semiconductor material, and the silicon wafer is placed On the base, the gate voltage is introduced at the bottom of the base.

Wherein, the silicon wafer includes a SiO ₂ layer and a Si layer, and the Si layer is covered with a SiO ₂ layer.

The preparation method of the device comprises the following steps:

S1: Thermally evaporate noble metal nanoparticles on silicon dioxide/monocrystalline silicon wafers to obtain noble metal nanomaterial substrates; according to the appropriate laser wavelength, deposit metal nanoparticles with different thicknesses by thermal evaporation, for example, when using a 532nm laser 10nm silver nanoparticles can be thermally evaporated;

S2: transfer the two-dimensional semiconductor material to the noble metal nanoparticle substrate prepared in S1, and wash to ensure the surface is clean;

S3: Evaporate gold/chromium nanoparticles onto the composite substrate of two-dimensional semiconductor material and metal nanoparticles prepared in S2 in the order of first chromium and then gold by thermal evaporation as source/drain;

S4: using the base to introduce gate voltage at the bottom of the device fabricated in S3. (Generally the breakdown voltage of the SiO ₂ layer on the silicon wafer is 110V).

Wherein, the thickness of the noble metal nanoparticles thermally evaporated in S1 is 1-100 nm.

The thickness of chromium in S3 is 5nm, and the thickness of gold is 80-100nm.

The size and gap of the source/drain electrodes in S3 can be adjusted, and the target molecule is located between the two electrodes.

Device of the present invention can be used for following determination:

(1) Utilize the device in the present invention to measure the current diagram under different gate voltages (-60V～60V) and bias voltage (-1.0V～1.0V);

(2) Utilize the device in the present invention to measure the Raman spectrogram of the catalytic reaction process under different laser wavelengths (200nm～1000nm) and light intensity (5uW～10mW);

(3) under a certain fixed laser wavelength (200nm～1000nm) and a certain light intensity (5uW～10mW) and a certain fixed gate voltage (-60V～60V) measured by the device in the present invention, the bias voltage (-1.0V ~1.0V) driven Raman spectrum of surface catalytic reaction process;

(4) Utilize the device in the present invention to measure different laser wavelengths (200nm～1000nm) and light intensity (5uW～10mW), the surface under different gate voltages (-60V～60V) and bias voltage (-1.0V～1.0V) Raman spectrum of the catalytic reaction process.

The beneficial effects of above-mentioned technical scheme of the present invention are as follows:

(1) When making the device, the size of the gap between the source and the drain is controllable due to the convenient control of the size of the shelter, and different sizes of gaps can be designed according to the needs of specific experiments to increase the available area for molecular reactions, and then Improve the local surface plasmon resonance effect and improve the efficiency of surface catalytic reactions;

(2) As long as the two-dimensional semiconductor material is properly transferred, the size of the device is very easy to control, thus greatly reducing the manufacturing cost of the device, and it is easier to introduce electric field regulation into the system;

(3) The structural design of the device is suitable for photoelectric coordinated control, and the control function of the incident light source will not be affected when the electric field is introduced.

In addition, the advantages of the photoelectric cooperative regulation of the surface plasmon-exciton coupling catalytic reaction of the present invention are as follows:

(1) While ensuring that the laser-regulated surface plasmon-exciton coupling catalytic reaction is not affected, an electric field is introduced to regulate the surface plasmon-exciton coupling catalytic reaction. Therefore, the adjustable parameters are greatly increased, making the surface The driving methods of catalytic reactions have become diverse. At the same time, the electrical performance of the device can be measured to explain the improvement in the performance of the surface catalytic reaction;

(2) By adjusting the gate voltage, the Fermi surface of the coupling system of two-dimensional semiconductor materials (single layer graphene, etc.) the efficiency of the reaction;

(3) By adjusting the bias voltage to generate current, the hot electrons generated by plasmons can obtain greater kinetic energy, promote the occurrence of surface catalytic reactions, and improve catalytic efficiency;

(4) It is more conducive to in-depth analysis of the physical principles of the coupling between plasmons and excitons, as well as the participation mechanism of electrons in catalytic reactions.

Description of drawings

Fig. 1 is a schematic structural diagram of a photoelectric synergistic surface plasmon-exciton catalytic reaction device of the present invention;

Fig. 2 is the electrical measurement diagram of the surface plasmon-exciton coupling catalytic reaction device of the present invention when no target molecule is adsorbed and adsorbed (4NBT), (a) is the gate voltage and bias when the target molecule is not adsorbed (4NBT) 3D continuous graph of voltage-regulated current change, (b) is the 3D continuous graph of the gate voltage and bias voltage-regulated current change when the target molecule is adsorbed (4NBT), (c) is the gate voltage under different gate voltages when the target molecule is not adsorbed (4NBT) Bias-current diagram, (d) is the bias-current diagram under different gate voltages when the target molecule is adsorbed (4NBT), (e) is when the target molecule is not adsorbed (4NBT) and the bias voltage V _Bias = 0.1V Gate voltage-conductance diagram, (f) is the gate voltage-conductance diagram when the target molecule (4NBT) is adsorbed and the bias voltage V _Bias =0.1V;

Figure 3 is the Raman spectrum of the surface catalysis reaction process on the surface plasmon-exciton coupled catalytic reaction device under different laser power regulation;

Figure 4 is the Raman spectrum and schematic diagram (bias control) of photoelectric synergistic surface plasmon-exciton coupling catalytic reaction process, (a) is the surface with bias control under fixed laser power and gate voltage of 0V Plasmon-exciton coupling catalytic reaction, (b) is the surface plasmon-exciton coupling catalytic reaction under the fixed laser power and the gate voltage is 40V, and (c) is the fixed laser light intensity And when the gate voltage is -40V, the surface plasmon-exciton coupling catalytic reaction controlled by the bias voltage, (d) is the schematic diagram of the optoelectronic cooperative surface plasmon-exciton coupling catalytic reaction (bias control), where The white areas in the triangle are holes, and the black filled areas are electrons;

Figure 5 is the Raman spectrum and schematic diagram (gate voltage regulation) of photoelectric synergistic surface plasmon-exciton coupling catalytic reaction process, (a) is the surface with gate voltage regulation under fixed laser power and bias voltage of 0V Plasmon-exciton coupling catalytic reaction, (b) is the surface plasmon-exciton coupling catalytic reaction under the fixed laser power and the bias voltage is 1V, and the gate voltage is regulated, (c) is the fixed laser light intensity And when the bias voltage is -1V, the surface plasmon-exciton coupling catalytic reaction controlled by the gate voltage, (d) is the schematic diagram of the optoelectronic cooperative surface plasmon-exciton coupling catalytic reaction (gate voltage control), where The white areas in the triangle are holes, and the black filled areas are electrons.

Among them: 1-incident laser; 2-source/drain; 3-target molecule; 4-two-dimensional semiconductor material; 5-silver nanoparticles; 6-SiO ₂ layer; 7-Si layer.

Detailed ways

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will describe in detail with reference to the drawings and specific embodiments.

The invention provides a photoelectric cooperative surface plasmon-exciton catalytic reaction device and a preparation method.

1. Fabrication of optoelectronic synergistic surface plasmon-exciton coupled catalytic reaction devices:

的速率将10nm厚度的银纳米颗粒5沉积到有300nm厚二氧化硅的硅片上；1) In an environment with a vacuum of 8.6x10 ^-5 Pa at room temperature, use thermal evaporation to

Silver nanoparticles 5 with a thickness of 10nm are deposited onto a silicon wafer with a thickness of 300nm of silicon dioxide at a rate of 100nm;

2) After spin-coating PMMA (3000rpm, 1min) on the CVD-grown copper-based single-layer graphene, put it in a 0.5Mol/L ferric chloride solution to corrode the substrate for more than 4 hours until the copper-based substrate is removed to obtain a two-dimensional semiconductor material 4, after washing with deionized water for more than 4 times, transfer to the substrate with silver nanoparticles 5, and finally remove the PMMA on the graphene surface with acetone;

的速率沉积5nm厚的铬纳米颗粒，最后以

沉积90nm厚的金薄膜。光电协同表面等离激元-激子耦合催化反应器件的设计见图1，上方为入射激光1，源极/漏极2间为目标分子3，银纳米颗粒5热蒸发在SiO₂层6上，SiO₂层6下为Si层7。3) After cleaning and drying the single-layer graphene-silver nanoparticle substrate several times, add source/drain electrode 2 two electrodes on the both sides of the single-layer graphene-silver nanoparticle substrate with thermal evaporation, source/drain electrode 2 The gap between the two electrodes of the drain 2 is 60 microns, and the vacuum degree of the deposited metal is 1.10x10 ^-5 Pa. The specific steps include the following parts: First, a 60-micron wire is placed on a single-layer graphene-silver nanoparticle substrate, and then

Deposit 5nm thick chromium nanoparticles at a rate of

A 90 nm thick gold film was deposited. The design of photoelectric synergistic surface plasmon-exciton coupled catalytic reaction device is shown in Figure 1, the incident laser light 1 is on the top, the target molecule 3 is between the source/drain electrodes 2, and the silver nanoparticles 5 are thermally evaporated on the SiO ₂ layer 6 , SiO ₂ layer 6 under the Si layer 7.

2. Measurement of photoelectric synergistic surface plasmon-exciton coupled catalytic reactions:

1) In order to protect the target molecules, the current variation trend of the device under different gate voltages and bias voltages was measured on a vacuum probe station when the device was not adsorbed and adsorbed target molecules, as shown in Figure 2(ad). And when the target molecule is not adsorbed and adsorbed, the conductance changes with the gate voltage when the bias voltage is 0.1V, as shown in Figure 2 (ef). Among them, the single-layer graphene-silver nanoparticle substrate was soaked in 4NBT with a concentration of 1x10 ^-3 M for 3-4 hours so that the molecules could be evenly adsorbed to the surface of the device, washed with ethanol after soaking, and washed with high-purity Nitrogen to dry. Figure 2 proves that there is a coupling interaction between single-layer graphene and silver nanoparticles, that is, there is a coupling interaction between surface plasmons and excitons, and directly verifies that the novel device in the present invention is suitable for electrical measurements;

2) Regulate the difference in attenuation intensity (5.36uW/47.42uW/496.82uW/1.19Mw/2.37mW/4.93mW) of the 532nm laser (light intensity about 5mW), and use the novel device of the present invention to measure 4NBT molecules under different light intensities The Raman spectrogram of the molecular reaction kinetics process of the catalytic reaction to generate DMAB molecules is shown in Figure 3, where the integration time is 5 seconds, 1109cm ^-1 and 1306cm ^-1 belong to the Raman characteristic peaks of 4NBT, and 1390cm ^-1 and 1438cm ^{- 1} belongs to the characteristic peak of DMAB Raman. Figure 4 directly verifies that the new device in the present invention is suitable for the measurement of laser-regulated surface plasmon-exciton coupled catalytic reactions. At the same time, it can be obtained that when the 532nm laser intensity is 5.36uW, the surface catalytic reaction cannot occur, which is photoelectric synergy Regulating the occurrence of catalytic reactions provides a control group;

3) When the 532nm laser intensity is 5.36uW, when the measured gate voltage is 0V/40V, the bias voltage regulates the surface catalytic reaction, see Figure 4 (a-b). The data with a gate voltage of -40V was used as a control group to investigate the transfer process of electrons and holes in the surface plasmon-exciton coupling effect, as shown in Figure 4(c). Figure 4(d) is a schematic diagram of the electron transfer process in the bias-regulated plasmon-exciton coupled catalytic reaction.

4) When the 532nm laser intensity is 5.36uW, when the measurement bias voltage is 0V/1V/-1V respectively, the gate voltage regulates the surface catalytic reaction, see Figure 5(a-c). Figure 5(d) is a schematic diagram of the electron transfer process in the plasmon-exciton coupled catalytic reaction regulated by the gate voltage.

The above description is a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, these improvements and modifications It should also be regarded as the protection scope of the present invention.

Claims (4)

1. A photoelectric synergistic surface plasmon-exciton catalytic reaction device, characterized in that it includes a silicon wafer, a two-dimensional semiconductor material (4), a source/drain (2) and an incident laser (1), silicon The chip is covered with noble metal nanoparticles, the noble metal nanoparticles are covered with a two-dimensional semiconductor material (4), the source/drain (2) is located on the two-dimensional semiconductor material (4), the silicon chip is placed on the base, and the gate voltage is introduced at the bottom of the base ; The size and gap between the two electrodes of the source/drain (2) can be adjusted, the target molecule (3) is located between the two electrodes, and the thickness of the noble metal nanoparticles is 1-100nm. 2. The optoelectronic synergistic surface plasmon-exciton catalytic reaction device according to claim 1, characterized in that: the silicon wafer comprises a _SiO2 layer (6) and a Si layer (7), wherein the Si layer ( 7) Covered with SiO ₂ layer (6). 3. The method for preparing a photoelectric synergistic surface plasmon-exciton catalytic reaction device according to claim 1, characterized in that: comprising the following steps: S1: Thermally evaporate noble metal nanoparticles on a silicon wafer of silicon dioxide or single crystal silicon to obtain a noble metal nanomaterial substrate; S2: transfer the two-dimensional semiconductor material to the noble metal nanoparticle substrate prepared in S1, and wash to ensure the surface is clean; S3: Evaporate gold/chromium nanoparticles onto the composite substrate of two-dimensional semiconductor material and metal nanoparticles prepared in S2 in the order of first chromium and then gold by thermal evaporation as source/drain; S4: using the base to introduce gate voltage at the bottom of the device fabricated in S3. 4. The photoelectric synergistic surface plasmon-exciton catalytic reaction device preparation method according to claim 3, characterized in that: the thickness of chromium in the S3 is 5 nm, and the thickness of gold is 80-100 nm.

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