WO2019098814A1 - Process for the biomimetic synthesis of polyaniline compounds and use thereof to manufacture supercapacitors - Google Patents

Abstract

A novel method for producing haematin compounds with graphitic carbon nitrides with a high oxygen and phosphorus content (gCNOP) and the use thereof as catalysts for the biomimetic synthesis of polyanilines at very low pH is described. Preparation of PANI compounds using said gCNOP-haematin, and the use thereof to manufacture electrical charge storage devices, is also demonstrated. A method for stabilising suspensions of haematin in an acidic aqueous medium using co-solvents, and the use thereof in biomimetic PANI synthesis, is also described.

Description

 PROCESS OF BIOMIMETIC SYNTHESIS OF COMPOSITES OF

 POLIANILINE AND ITS USE IN THE MANUFACTURE OF SUPER CAPACITORS

DESCRIPTION

OBJECT OF THE INVENTION

Intrinsic conducting polymers have been used as raw material for the construction of capacitive and supercapacitive materials, for its ease of synthesis and low cost of the constituent monomer, polyaniline (PANI) is one of the most used polymers. However, the conductive properties of PANI are very influenced by their morphology and molecular weight, which is why several control methodologies of the two characteristics are studied. Among the strategies is the use of enzymes as templates and oxidizing agents, as well as the use of soft and solid templates to guide the morphology of the polymer. The use of enzymes has the advantage of producing high molecular weight polymers without using aggressive or environmentally unfavorable reagents, however its use does not lend itself readily to polymerization in aqueous media with high acid content. Considering that pH 1 favors the mass formation of high quality NIBP, it would be very useful to be able to carry out enzymatic polymerizations under this pH condition. Using the hematin, a metalloporphyrin that contains the reactive groups of oxo-reducing enzymes and is more stable and economical than those, in this invention we offer an alternative of polymerization of aniline at very low pHs using hematin compounds deposited on the surface of graphitic carbon nitrides as polymerization catalysts; the graphitic carbon nitrides confer stability to the hematin and additionally act as polymerization templates of the PANI. It is also the object of this invention to offer a new method of solvothermal preparation of graphitic carbon nitrides doped with oxygen and phosphorus, materials that we have used to synthesize the hematin-carbon nitride compounds described. BACKGROUND

At the end of the seventies, H. Shirakawa, AG MacDiarmid and AJ Heeger synthesized polyacetylene from acetylene, demonstrating that its structure of alternating double bonds allowed the flow of electricity, also showing that the material could behave as an insulator and, when doped with vapors of iodine and other halogens, the conductivity increased to give it metallic conductor properties (1-3). In the year 2000, the researchers won the Nobel Prize in Chemistry for this finding, which initiated the development of intrinsic conductor polymers, that is, those with conduction properties resulting from the ease of delocalization of the electron contained in the orbital p _z of double bonds and their mobility through the chain of conjugation.

However, the preparation of polyacetylene is complicated and does not lend itself to the manufacture of important quantities that allow its widespread commercial use, which, coupled with its instability, led to the development of other intrinsic conducting polymers that do not have these drawbacks. Among the developed ones are polythiophenes (PTH), polipirroles (PPY), poli- (p-phenylene) (PPP) and polyanilines (PANI), among others. Due to the affordability and low cost of aniline, the raw material with which it is made, polyaniline is the one that has attracted the most interest and accumulated the largest number of research works. The use of PANI has been studied in multiple applications, including rechargeable batteries (4), electromagnetic interference blocking (5), supercapacitors (6-9), sensors and indicators (10, 11), among others.

Although it is possible to obtain PANI by electrochemical oxidation (12, 13), this system does not allow the preparation of large amounts of polymer, so it is commonly synthesized by oxidation of the aniline in aqueous acidic media. In a procedure standardized by IUPAC, the addition of an aqueous solution of ammonium peroxodisulfate to aqueous solutions of aniline hydrochloride in a 1: 0.8 molar ratio at room temperature is described; after allowing to stand for 24 hours, the PANI in its emeraldine phase (polyaniline hydrochloride) is filtered and washed to obtain yields close to 100% (14). Although the method is simple and allows easy scaling to obtain PANI in bulk, given the insolubility of the polymer obtained, it does not lend itself to its easy use as a raw material in some applications. Additionally, in many of them it is necessary to have a product with specific characteristics in which the size and morphology of the material are decisive. For this reason, various preparatory methods have been studied that make it possible to control some of their properties; Among the studied variations, the synthesis is highlighted using soft and strong templates as well as self-assembly variations that allow to modulate the size and morphology of the polymers obtained (15-21). Likewise, preparative variations have been investigated that generate purer materials and avoid or diminish the use of strong oxidative systems; In this group the methods in which enzymes are used stand out, taking advantage of the fact that these are natural catalysts that are non-toxic, biodegradable, energy efficient and obtained from renewable sources. Since they use or mimic actions performed in biological media, enzymatic syntheses are called biomimetics. Despite the advantages they offer, enzymes are usually thermally and chemically unstable, which is why they are commonly immobilized on solid substrates that facilitate their handling and increase their stability (22-26).

As examples of enzymatic synthesis of PANI and the use of substrates for their immobilization, several working groups have used horseradish peroxidase (HRP) in the oxidative polymerization of phenols and anilines in the presence of hydrogen peroxide (27, 28). Datta et al studied in detail the use of DNA and other polyanions as a template for enzymatic polymerization (29). Huh et al. Synthesized a copolymer of aniline and 3-aminobenzeneboronic acid using HRP as a catalyst and sulfonated polystyrene as a template (30). Nabid and Entezami have studied PANIs synthesized by this method using different aniline monomers (31). Romero et al reported the use of soy peroxidase (SBP) for the enzymatic polymerization of PANI in aqueous medium at pH 3 using p-toluenesulfonic acid (TSA) as a dopant (32), The polymer has structural properties similar to that obtained by conventional chemical oxidation. Kim et al polymerized three different aniline monomers using HRP at pH 3 in partially organic medium using ethanol as a cosolvent (33). Takamuku et al reported the use of non-ionic polymers such as polyvinylpyrrolidone, ethylene polyoxide and polyvinyl alcohol (PVA) as stabilizers during the enzymatic polymerization of aniline (34). Romero et al studied the enzymatic synthesis of PANI using a hydrolyzed colloid of PVA, poly (N-isopropylacrylamide) and chitosan as a steric stabilizer and camphorsulfonic acid (CSA) or para-toluenesulfonic acid (TSA) as dopants, finding a strong dependence on the morphology of the colloids with doping and the modification of the hydrophobicity of the PANI according to the acids used (35).

Although the use of enzymes has demonstrated its efficiency in the preparation of PANI, its cost and difficulty in handling acid media inhibit its use on a large scale, so it would be useful to have lower-priced options that have the oxidative activity of the enzymes Gonsalves published the use of hldroxiferríprotoporfirina or hematina as an economic substitute of the enzymes used in the oxidative polymerization of phenols (36), the compound contains the active group of many peroxidases, being able to substitute them in oxidative reactions, surpassing them by its greater stability and lower cost. The publication of Goncalves is followed by a report by Sakai et al who used hematin for the oxidative removal of phenols (37) and an article by Ravichandran in which they stabilize the hematin and prevent its separation from the acidic reaction medium by containing it in generated micelles and stabilized with dodecylbenzenesulfonic acid; The polypyrrole is obtained after adding pyrrole and hydrogen peroxide to the suspensions (38). Romero et al published a hematine support method on a nanotubular substrate of aluminosilicate with which they were able to polymerize biomimetically aniline and obtain salt of emeraldine, given the adequate stability and catalytic activity in an acid medium of the nanocomposite haloisite / hematin (39). Other publications describe the deposit of hematin on graphene and the use of the nanocomposite for the electrochemical detection of H2O2 and glucose (40); The preparation of a biosensor for the detection of cholesterol using a nanocomposite of hematine on graphene has also been described, the device takes advantage of the oxidative property of the former (41). The oxidative removal of pyrogallol has been reported using a nanocomposite of hematine on graphene, in which hematin retains its excellent oxidative capacity (42). Zhang et al reported the composition Hematina-SWCNT using it in the detection of H2O2 (43) while the nanocomposite generated from hematine-graphene oxide-carbon nanotubes (H-GO-CNTs) was used in the manufacture of a dual biosensor for determination of H2O2 and simultaneously Trp, AA, DA and UA (44).

In some of the previous examples, uni and bidemensional materials are used as enzyme deposit substrates; Among the possible alternatives of enzyme immobilization substrates, the use of graphitic carbon nitrides (gCN) is being studied. The gCN are two-dimensional materials structurally similar to graphene; Although recently developed, graphite carbon nitrides have been the subject of intense study, particularly employing them as photocatalysts (45). Carbon nitrides are commonly prepared by thermal polymerization of low molecular weight molecules rich in nitrogen and carbon, among the most common being melamine [46], cyanamide [47], dicyanamide [48], thiourea [49] and urea [50-54]. During the formation of nitrides, the raw materials give rise to increasingly complex intermediates, among them the cyanuric acid and the melanin, which is dimerized (melam) and then converted to melem (2,5,8-Triamine). tri-s-triazine) and finally to the graphitic carbon nitride; Regardless of the precursors used and except for differences in yield and morphology of the final product, the polymer is always composed of melem units [55].

Some of the strategies for the structural manipulation of carbon nitrides are based on those used to modify inorganic semiconductors through doping with metals and their oxides [56-62] or by the incorporation of atoms that are incorporated into the structure of the nitrides in replacement of some of the carbon or nitrogen atoms that make up the polymer network. Watts articles refer to the modifications in the bandgap that arose when incorporating atoms of B [63], N [64], O [65], S [66] and P in the sheets of gC3N4 that increase mobility electronics and generate new reactive groups. Zhang published the first article on the doping of carbon nitrides with phosphorus, in which he demonstrates that the material obtained has a greater electrical conductivity (four orders of magnitude higher than that generated by the non-doped material) and produces a greater quantity of photocurrent [ 67), the synthesis is based on the pyrolysis of dicyanamide in the presence of BmimPF6 (1-butif-3-methylimidazo! io hexafluorophosphate) a non-volatile ionic liquid that remains in the reaction mixture treated at a high temperature. This example is followed by another one by Mu et al in which the synthesis procedure is replicated, showing the removal capacity of Methyl Orange and Rhodamine B by photocatalysis under visible light and indicating the morphological, optical and electrical differences of the product [68].

Other manufacturing processes of phosphorus-doped nitrides have been published, Hu et al synthesized a photocatalyst by pyrolysis of a mixture of cyanamide with diammonium hydrogen phosphate, the material showed a lower separation energy of the forbidden band and increased the separation efficiency of the electron-hole pair [69], The thermal treatment (550 ° C - 650 ° C) of mixtures of guanidinium hydrochloride and hexachlorophosphazene as precursors of products doped with phosphorus has been reported, the authors post the introduction of phosphorus in substitution of carbon in the structure of heptazines; it was shown that the materials are useful to photocatalytically remove several organic dyes [70]. The synthesis from melanin with hydroxyethylidene diphosphonic acid with a weight ratio of 15: 1 has been described, the mixture is heated to 500 ° C and maintained at that temperature for 3 hours under a stream of nitrogen [71]. The synthesis from 2-aminoethyl-phosphonic acid and melamine (1:60 weight ratio) has been described, the product was made by thermoforming at 500 ° C using one hour of heating ramp and 3 hours of heat treatment under atmosphere followed by 5 hours of a second treatment at 550 ° C, the material obtained was milled and heat treated again at 500 ° C by two additional hours to achieve its best exfoliation [72]. The manufacture of phosphorus-doped nitride nano-nitrides by heat treatment of 1: 10 by weight mixtures of phytic acid with melamine has been demonstrated, both materials were dissolved in water, once the water was removed by gentle heating, the solid it was heated for three hours at 550 ° C to treat again for four additional hours at the same temperature under a nitrogen atmosphere, the product was oxidized by heating at 120 ° C in nitric acid for twelve hours to finish with a hydrothermal treatment at 200 ° C for 20 h; the materials showed to be highly fluorescent and useful in the detection of acetylcholinesterase [73]. The same group reports a variation of this procedure and the use of carbon nitride nano-points as biological visualization aids [74]. Other reported synthesis procedures employ 12-hour mechanical grinding treatments at 400 rpm of mixtures of gC3N4 with red phosphorus [75], pyrolysis of 1:10 by weight mixtures of nitrilotris (methylene) -triphosphonic acid with dicyandiamide at 600 ° C for four hours, after a heating ramp of 10 ° C / min [76]. Lan et al published the manufacture of mass carbon nitride doped with phosphorus by pyrolyzing mixtures of melamine with hexachlorotriphosphazene for two hours at 530 ° C in a semi-closed crucible [77]. A recent preparative process of doped materials describes the hydrothermal treatment of mixtures of melamine with phosphorous acid (10 hours at 180 ° C) followed by a thermal treatment of the intermediate material for 4 hours at 500 ° C [78]. As listed, all published phosphorus-based synthesis methods of gCsISU make use of pyrolysis of mixtures of the nitride precursors with phosphorus feedstocks; given the loss of gaseous intermediates in the reaction mixture, the heat treatments have relatively low yields of the final products, even in cases where they are carried out in semi-closed containers.

In general, the aromatic two-dimensional structure of graphite nitrides allows the formation of compounds with planar materials through the pi-pi interaction of the respective electronic clouds. There are a small number of examples that describe their doping with different metallo-porphyrins, the nanocomposites obtained have been used as photocatalysts in the degradation of phenol (79) and the photocatalytic reduction of CO ₂ (80); they have also been used for the photocatalytic generation of hydrogen (81, 82). In a small number of publications the deposit of enzymes on gCN is described, the compounds have been successfully evaluated as sensors in the detection of markers of cancer (83), cholesterol (84) and pesticides (85); however, the deposition of haematine on graphitic carbon nitrides and the possible use of the resin nanocomposites have not been described.

In this invention we describe a method not previously reported that allows the easy preparation of graphitic carbon nitrides with high content of oxygen and phosphorus (gCNOP) as well as the elaboration of nanocomposites of hematine with the developed nitrides. The synthesis of gCNOP and its nanocomposites with hematin has not been described before in the technical or scientific literature. In the present invention we show the usefulness of these materials as catalysts in the biomimetic synthesis of polyanilines at very low pHs and with it the preparation of PANI compounds with gCNOP; We also describe the use of the latter as raw materials suitable for manufacturing electrical charge storage devices.

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 66.- Sulfur-doped g-C3N4 with enhanced photocatalytic C02-reduction performance; Ke Wang, Qin Li, Baoshun Liu, Bei Cheng, Wingkei Ho, Jiaguo

Yu; Applied Catalysis B: Environmental 176-177 (2015) 44-52

 67.- Phosphorus-Doped Carbon Nitride Solid: Enhanced Electrical Conductivity and Photocurrent Generation; Yuanjian Zhang, Toshiyuki Mori, Jinhua Ye, and Markus Antonietti; J. Am. Chem. Soc. 2010, 132, 6294-6295]

68.- Facile synthesis of phosphorus doped graphitic carbon nitride polymers with enhanced visible-light photocatalytic activity; Ligang Zhang, Xiufang Chen, Jing Guan, Yijun Jiang, Tonggang Hou, Xindong Mu; Materials Research Bulletin 48 (2013) 3485-3491. 69.- A simple and efficient method to prepare phosphorus modified g-C3N4 visible light photocataiyst; Shaozheng Hu, Lin Ma, Jiguang You b, Fayun Li, Zhiping Fan, Fei Wang, Dan Liud and Jianzhou Gui; RSC Adv., 2014, 4, 21657.

70.- Brand new P-doped g-C3N4: enhanced photocatalytic activity for H2 evolution and Rhodamine B degradation under visible light; Yajun Zhou, Lingxia

Zhang, Jianjun Liu, Xiangqian Fan, Beizhou Wang, Min Wang, Wenchao Ren, Jin Wang, Mengli Li and Jianlin Shi; J. Mater. Chem. A, 2015, 3, 3862.

 71.- Mesoporous Phosphorus-Doped g-C3N4 Nanostructured Flowers with Superior Photocatalytic Hydrogen Evolution Performance; Yun-Pei Zhu, Tie-Zhen Ren, and Zhong-Yong Yuan; ACS Appl. Mater. Interfaces 2015, 7, 16850-16856.

 72.- Porous P-doped graphitic carbon nitride nanosheets for synergistically enhanced visible-light photocatalytic H2 production; Jingrun Ran, Tian Yi Ma, Guoping Gao, Xi-Wen Du and Shi Zhang Qiao; Energy Environ. Sci., 2015, 8, 3708.

 73.- Synthesis of highly fluorescent P, 0-g-C3N4 nanodots for the label-free detection of Cu2 + and acetylcholinesterase activity; Mingcong Rong, Xinhong Song, Tingting Zhao, Qiuhong Yao, Yiru Wanga and Xi Chen; J. Mater. Chem. C, 2015, 3, 10916.

74.- Study on the Ultrahigh Quantum Yield of Fluorescent P, 0-g-C3N4

Nanodots and its Application in Cell Imaging; Mingcong Rong, Zhixiong Cai, Lei Xie, Chunshui Lin, Xinhong Song, Feng Luo, Yiru Wang, [a] and Xi Chen; Chem. Eur. J. 2016, 22, 9387-9395. 75.- Facile and Scale Up Synthesis of Red Phosphorus-Graphitic Carbon Nitride Heterostructures for Energy and Environment Applications; Sajid Aii Ansari, Mohammad Omaish Ansari & Moo Hwan Cho; Scientific Reports | 6: 27713 | DOI: 10.1038 / srep27713.

 76.- Three-Dimensional Phosphorus-Doped Graphitic-C3N4 Self-Assembly with NH2-Functionalized Carbon Composite Materials for Enhanced Oxygen Reduction Reaction; Yang Qiu, Le Xin, Fan Jia, Jian Xie, and Wenzhen Li; Langmuir 2016, 32, 12569-12578.

 77.- Phosphorous-modified bulk graphitic carbon nitride: Facile preparation and application as an acid-base bifunctional and efficient catalyst for C02 cycloaddition with epoxides; Dong-Hui Lan, Hong-Tao Wang, Lang Chen, Chak-Tong Au, Shuang-Feng Yin; Carbon 100 (2016) 81 - 89.

 78.- Phosphorus-Doped Carbon Nitride Tubes with a Layered Microstructure for Enhanced Visible-Light Photocatalytic Hydrogen Evolution; Shien Guo, Deng Zhaopeng, Li Mingxia, Baojiang Jiang, Tian Chungui, Qingjiang Pan, Honggang Fu; Angew. Chemie Volume 55, Issue 5 January 26, 2016 Pages 1830-1834.

 79.- Visible light photoactivity enhancement via CuTCPP hybridized g-C3N4 nanocomposite; Appl. Catal. B Environ. 2015, 166-167, 366-373.

80.- Co-porphyrin / carbon nitride hybrids for improved photocatalytic C02 reduction under visible light; Guixia Zhao, Hong Pang, Guigao Liu, Peng Li, Huimin Liu, Huabin Zhang, Li Shi, Jinhua Ye; Applied Catalysis B: Environmental 200 (2017) 141-149 81.- A puree organic heterostructure of m-oxo dimeric iron (lll) porphyrin and graphitic-C3N4 for solar H2 production from water; DH Wang, JN Pan, HH Li, JJ Liu, YB Wang, LT Kang and JN Yao, J. Mater. Chem. A, 2016, 4, 290-296.

82.- Enhanced visible light photocatalytic hydrogen evolution over porphyrin hybridized graphitic carbon nitride; Mei Shunkang, Gao Jianping, Ye Zhang, Yang Jiangbing, Wu Yongli, Xiaoxue Wang, Ruiru Zhao, Xiangang Zhai, Chaoyue Hao, Ruixia Li, Jing Yan; Journal of Colloid and Interface Science 506 (2017) 58-65

83.- Dual-responsive competitive immunosensor for detection of tumor marker on g-CN / rGO conjugation; Huixiang Yan, Lingshan Gong, Lele Zang, Hong Dai, Guifang Xu, Shupei Zhang, Yanyu Lin; Sensors and Actuators B 230 (2016) 810-817

 84.- In situ synthesis of cylindrical spongy polypyrrole doped protonated graphitic carbon nitride for sensing application; Bishnu Kumar

Shrestha, Rafiq Ahmad, Sita Shrestha, Chan Hee Park, Cheol Sang Kim; Biosensors and Bioelectronics, Volume 94, 15 August 2017, Pages 686-693

85.- MLtrasensitive electrochemiluminescence biosensor for organophosphate pesticides detection based on carboxylated graphitic carbon nitride-poly (ethylenimine) and acetylcholinesterase; Wang Bingxin, Xia Zhong, Yaqin Chai, Ruo Yuan; Electrochimica Acta 224 (2017) 194-200

 86.- A review of electrode materials for electrochemical supercapacitors: Guoping Wang, Lei Zhang and Jiujun Zhan; Chem. Soc. Rev., 2012, 41, 797-

828 87.- Functionalized-Graphene / Polyaniline Nanocomposites as Proficient Energy Storage Material: An OverView; Dipanwita Majumdar; Innov Ener Res 2016, 5: 2

88.- Graphene and Polymer Composites for Supercapacitor Applications: a Review; Yang Gao; Nanoscale Research Letters (2017) 12: 387

 89.- Graphene Oxide / Polyaniline Composites as Electrode Material for Supercapacitors; Sandeep Chauhan: J. Chem. Pharm. Res., 2017, 9 (4): 285-291

 90.- Nanostructured Electrode Materials for Electrochemical Capacitor Applications; Hojin Choi and Hyeonseok Yoon; Nanomaterials 2015, 5, 906-936; doi: 10.3390 / nano5020906

 91.- Supercapacitor electrode materials: nanostructures from 0 to 3 dimensions; Zenan Yu, Laurene Tetard, I read Zhai and Jayan Thomas; Energy Environ. Sci., 2015, 8, 702

 92.- Supercapacitor and supercapattery as emerging electrochemical energy stores; George Z. Chen; INTERNATIONAL MATERIALS REVIEWS, 2017 VOL. 62, NO. 4, 173-202, http://dx.doi.org/10.1080/09506608.2016.1240914

BRIEF DESCRIPTION OF THE FIGURES

 Figure 1 Infrared spectrum of graphitic carbon nitride with high content of oxygen and phosphorus (gCNOP).

 Figure 2 Electron transmission electron microscopy (gCNOP).

 Figure 3 X-ray diffractogram of (gCNOP).

Figure 4 13C NMR spectrum of gCNOP Figure 5 31 P NMR spectrum of gCNOP

 Figure 6 X-ray diffractogram of compound gCNOP-hematin

 Figure 7 Scanning electron microscopy of gCNOP-hematin-PANI

 Figure 8 X-ray diffractogram of gCNOP-hematin-NIBP

 Figure 9 Infrared spectra of gCNOP-hematin-PANI

 Figure 10 Cyclic Votagrams of PANI-gCNOP and PANI Free Compounds

Figure 11 Measurements of galvanostatic charge-discharge of compounds of

PANI-gCNOP and PANI free

 Figure 12 Hematine X-ray diffractogram-PANI

 Figure 13 Scanning electron microscopy of hematine-PANI

DETAILED DESCRIPTION OF THE INVENTION

We describe here the synthesis of graphitic carbon nitrides with high content of oxygen and phosphorus (gCNOP) using a solvotermal method of high performance in a single step. We show that, like the graphitic carbon nitrides (gCN) prepared by thermolysis, gCNOP are two-dimensional materials formed by a network of aromatic molecules derived from triazines, are chemically very stable and easily form suspensions in aqueous acid media. Its planar structure rich in orbitals p _z allows the formation of compounds with flat aromatic materials via the interaction ττ-π of their respective electronic clouds and by means of the formation of Hydrogen bonds. Taking advantage of this feature we prepare gCNOP-hematin compounds; these form stable aqueous acid suspensions in which the hematin remains bound to the nitrides. We found that hematin maintains its catalytic properties by enabling the biomimetic polymerization of aniline by oxidation with hydrogen peroxide. The polymer, formed with a yield higher than 80%, is of high quality, judging from the color of the emeraldine synthesized and the analyzes made to the polymers. The observations made by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) show that polyaniline is deposited in laminar form on nitrides and that these act as templates that direct the growth of polymer chains. When carrying out the electrochemical evaluation of the gCNOP-hematin-PANI nanocomposites, we prove that they have electric charge storage properties that make possible their use as raw materials for the manufacture of supercapacitors.

The general procedure for obtaining phosphorus-modified oxidized graphitic carbon nitride is carried out by mixing urea and phosphorus pentoxide in a non-polar inert solvent such as hexane, toluene or xylene, the mixture is heated for several hours, within a certain range of temperature from 200 ° C to 300 ° C, in a steel autoclave provided with an internal container manufactured with plastic materials capable of tolerating high temperatures and pressures as well as corrosive conditions. Satisfied the reaction time, the autoclave is removed from the heating system and allowed to cool naturally to room temperature; the formed solid is washed Repeatedly with common organic solvents and dried for several hours at 70 ° C in an electric oven. In this way, straw-white solids with yields of 60 to 80% by weight are obtained, based on the weight of the reagents used.

In a typical experiment 400 mg of urea are placed in a glass vial with 30 mL of toluene and added, taking care not to expose it to atmospheric humidity, 100 mg of phosphorus pentoxide (P ₂ O ₅ ), the mixture is stirred vigorously for 15 min with the aid of a Vortex 2 Genie mixer. The suspension is transferred to a Teflon cylinder, sealed in a stainless steel autoclave, the system is introduced to a preheated oven at 230 ° C in an electric heater. After several hours of heating the autoclave is cooled and opened to remove the solid formed; it is dispersed for one hour, in an ultrasonic cleaning bath, in an aqueous solution with a pH of 1; the suspension is filtered using a Teflon filter of 0.25 μm) washing four times with ethanol, water and acetone, the filtered solid is dried for 24 hours at 70 ° C. Different variables were evaluated using this procedure, among them the reaction time , temperature, solvent, source of phosphorus, proportion by weight of urea / source of phosphorus and proportion by weight of the mixture of solids / solvent; Table 1 shows some of the typical results of solvothermal treatment comparing them with those obtained by pyrolytic treatment in a tubular furnace.

 Table 1. Yields of gCNOP 0 under different reaction conditions.

The results shown indicate the influence of the solvent, temperature and. reaction time on gCNOP yields; these point to the advantage of using hexane on toluene as a solvent, as well as the increase in performance by increasing the temperature. When observing the results shown highlights that thermolitic synthesis methods of carbon nitrides generate low yields, usually less than 10% by weight of the precursors used; by comparison, with the procedure described herein yields greater than 60% by weight of the urea used are obtained, which indicates the advantage of using the preparative method described herein. The observation is consistent with the yields obtained by the conventional pyrolytic method, with which very low yields of non-oxidized graphitic carbon nitrides are obtained.

The Fourier transform infrared spectra (FTIR) show that the materials are very similar to the gCN synthesized by thermolysis but present additional signals characteristic of oxygen-containing functional groups. Figure 1 shows the FTIR spectrum of the product obtained, the region of 1200-1650 cm ^-1 has multiple absorption bands that, due to intensity and position, are typical of g-CN, melem [2,6-triamine- s-heptazine

heptazine

cantaloupe

and other CN hetero rings. Transmission electron microscopy (TEM) verify that the materials are two-dimensional; Figure 2 shows the micrograph obtained by TEM of the product, it is observed that the shape of the sheets is irregular and mesoporous, which confirms the formation of structures associated with oxidized carbon nitrides. The difractog X-ray branches (XRD) corroborate this by showing the reflections at 2Θ-10.8 (d = 0.818 nm) and 27.79 ° (d = 0.319 nm) characteristics of the oxidized carbon nitride (Figure 3). Figures 4 and 5 show the nuclear magnetic resonance (NMR) spectra of 13 C and 31 P acquired for the product reported, in the Experimental spectrum of modified g-OCN (Figure 4) The signal at 135.7 ppm is attributed to carbons in position Οβ. In the spectrum of Figure 5 match a signal -3.0 ppm suggesting a functional species phosphorus type -PO ₄ is shown. The elemental analysis of the material, obtained by emission photoelectron spectroscopy (XPS), indicates that it contains 33.5% carbon, 37.4% nitrogen, 25.5% oxygen and 3.6% phosphorus. The information is compatible with the expected observations of a two-dimensional material with a functionalized structure as proposed.

We find that the materials obtained form hematin compounds by mixing a solution of that with suspensions of the nitrides. In a typical procedure for preparing the gCNOP-hematin compounds, the haematin is dissolved in a bicarbonate / sodium carbonate buffer solution (pH 10) and magnetically mixed with a suspension of gCNOP in water for 24 hours. After mixing for one day, the suspension is centrifuged and the solid is deposited on a 25 micron Teflon membrane, washed repeatedly with a bicarbonate / sodium carbonate buffer solution (pH 10) and finally dried for 24 h at 70 ° C. C in an electric oven. The solids obtained have a faint green color and the X-ray diffractograms show the crystalline reflections of the original gCNOP and those typically found in the hematin, showing that it was deposited on the nitride (Figure 6). We determined that the compound forms stable suspensions throughout the pH range, without releasing the hematin deposited on the nitride; Below we show that this stability it can be used with advantage to carry out the polymerization of aniline at a low pH.

When evaluating the use of the gCNOP-hematine compounds as catalysts of the polymerization process of aniline by oxidation with hydrogen peroxide, we find that the compounds lead to the rapid formation of PANI with high yield and that the polymer is deposited on the compound forming laminar structures that take the form of the catalyst compound, showing that it also acts as a template for forming the polymer sheets. Considering that the polymerization of aniline is facilitated in acidic mediums that promote the formation of high quality emeraldine, the polymerization described herein is carried out in aqueous acidic medium with a pH of 1, reached by the addition of para-toluenesulfonic acid to the medium of reaction. In the synthesis procedure we use a variant of the reported preparative methods of adding hydrogen peroxide to an acid solution of aniline, with the advantage of being able to do it at a very low pH in which the hematin is stable because it is deposited on the sheets of oxidized graphite carbon nitride. In the microphotographs of SEM (Figure 7) we can notice the presence of microparticles smaller than 5 microns and the existence of large platelets coated with polymer. X-ray diffractometry shows a signal at 20 = 27.2 ° which corresponds to the plane (002) of graphitic carbon nitrides and signals that appear at 29 = 15, 20 and 26 °, corresponding to planes (011), (020) ) and (200) of PANI (Figure 8). In the infrared spectrum we can see the presence of the common absorption bands of polyaniline (Figure 9). These observations are consistent with those expected in a compound with the structure and composition proposed here.

 Polyaniline polymers have been studied as raw materials for the storage of cargo for more than thirty years, taking advantage of them as conductive or electroactive agents (86-89); in this period it has been proven that its dimensionality and morphology have a significant influence on its characteristics (90-92). We find that the compounds prepared using the method detailed here can be used as materials for the storage of cargo; for this, its specific capacitance measured by cyclic voltammetry and galvanostatic charge-discharge (Figures 10 and 11) was evaluated. The results of the measurements indicate that the specific capacitance measured by cyclic voltammetry is 387.9 F / g at 10 mV / s) while measured by galvanostatic charge-discharge is 293 F / g at 5 A / g.

To compare the charge storage capacity of the gCNOP-PANI compounds obtained by hematin catalysis with the preparations in the absence of the graphitic carbon nitrides, we developed a method of stabilizing hematin in an acidic medium (pH 1). For this purpose we evaluated the effect of mixing different solvents with water in the presence of para-toluenesulfonic acid at pH 1, determining that the hematin remained suspended in the reaction medium throughout the pH range when using volumetric mixtures 4: 1 of water- dimethyl sulfoxide; we show that the haematine thus suspended catalyzes the polymerization of aniline and allows obtaining polymers of this with high yields, of the order of 65%, a result similar or superior to those reported by Romero (32) in a similar polymerization catalyzed by soy peroxidase but made at a pH of 3 or 5 in which the NIBP obtained do not have the highest possible quality; the same author described the polymerization of aniline catalyzed by hematin using a haloisite substrate to stabilize the porphyrin at a pH of 2 (39). The polymerization catalyzed by a stabilized suspension of hematine at pH 1, using the binary solvent system described above, without using support substrates, has not been previously reported; its success derives from the stabilization of hematin at a very low, acidic pH that facilitates the clean conversion of aniline to the polymer. In relation to the aforementioned, we find that the hematin is kept in suspension by adding para-toluenesulfonic acid to the reaction medium until reaching a pH of 1 using a 4: 1 by volume mixture of water with dimethyl sulfoxide (DMSO), showing that the polymerization of aniline to PANI is carried out satisfactorily. When observing the polymer obtained by means of scanning electron microscopy we see that it is formed by agglomerated globules with larger particles than those observed in the PANI compounds on gCNOP (Figure 13); The X-ray diffractogram (Figure 12) shows signals similar to those obtained when analyzing the PANI-gCNOP-hematin compound, indicating that the two materials are very similar, differing in their morphology. However, the charge storage properties of the second are lower than those of the compound containing the graphitic carbon nitrides (Figures 10 and 11). The measurements of specific capacitance measured by cyclic voltammetry yield a value of 227 F / g at 10 mV / s while the measurement by galvanostatic charge-discharge is 83 F / g at 5 A / g. The comparative results of the materials indicate that PANI manufactured using graphite carbon nitrides as a catalyst-substrate has better supercapacitive properties than the polymer obtained by hematin catalysis in the absence of the gCNOP sheets, indicating the advantage of using them as a synthesis substrate of supercapacitive materials. We attribute the difference that the carbon nitride substrate is a porous material that facilitates contact with the electrolyte. The examples given below show the synthesis and handling conditions typically employed to prepare the described materials.

Example 1 Synthesis of gCNOP

In a typical experiment, 400 mg of urea are placed in 30 mL of hexane, 100 mg of phosphorus pentoxide (P2O5) are added to the mixture (taking care not to expose it to atmospheric humidity) and agitated vigorously (assisted by a Vortex 2 Genie). maximum power) in a glass vial for 15 min. The suspension is transferred to a Teflon cylinder by sealing it in a stainless steel autoclave and maintained for four hours at 220 ° C in an electric stove, different reaction times, temperatures, solvents and phosphorus sources were evaluated according to table 1 , the recovered solid is dispersed in an aqueous solution (pH 1) in μLonic bath for 1 hour, the suspension obtained is filtered (Teflon 0.25 μm filter) and washed with ethanol, water and acetone 4 times, the filtered solid is dried for 24 h at 70 ° C, the recovered white solid is weighed and stored for further testing. The yield obtained from the raw material is 64%. Example 2 Preparation of gCNOP-hematin compound

Hematin (10 mg) is dissolved in 20 mL of a buffer solution (bicarbonate / carbonate pH 10) in a 40 mL vial while stirring magnetically for 30 minutes. To the solution is added 500 mg of g-CNOP obtained following the procedure described in example 1, the vial is immersed for 15 min in an ultrasonic bath and then the solution is magnetically stirred at 1,000 rpm for 24 h. The suspension is centrifuged at 14,000 rpm for 30 min and the faint green solid is filtered using a 0.25 μm Teflon filter. The material is washed 4 times with carbonates buffer (pH 10) and finally dried for 24 h at 40 ° C. The material forms stable colloidal suspensions on the entire pH scale.

Example 3 Preparation of PANI-gCNOP-hematin compound

100 mg of the compound of gCNOP-hematin is dispersed by treating it by ultrasound (40 Hz) in 20 mL of deionized water for 5 min at 25 C; P-toluenesulfonic acid is added to the dispersion to bring the pH to 1. The dispersion is stabilized for 2 h under magnetic stirring, then 200 μL of aniline are added to the system and constant agitation is maintained at 1000 rpm for 12 h. 500 μL of 30% H2O2 are microdosed to the suspension by peristaltic pump for 9 min at 0 ° C, once the addition is complete the mixture is kept at that temperature, with stirring, for 12 h. The recovered dark green solid is filtered (Teflon 0.25 um) and washed with deionized water, ethanol and acetone until the filtered liquid is colorless; the solid is dried at 70 C for 24 h to obtain an 85% yield.

EXAMPLE 4 Biomimetic polymerization of aniline in co-solvent H ₂ O / DMSO In a typical preparation 10 mg of hematin are dissolved in 1 mL of dimethyl sulfoxide (DMSO) and magnetically stirred at 1,000 rpm for 2 h, subsequently add to a volume of 40 mL of a binary H ₂ O / DMSO solution (4: 1) and the mixture is dispersed by ultrasound (40 Hz cleaning bath) for 5 min at 25 ° C and then add p-toluenesulfonic acid until reaching pH 1; the dispersion is stabilized for 2 h by magnetic stirring, then 200 μL of aniline are added to the system and a constant stirring is maintained at 1000 rpm for 12 h. 500 μL of 30% H2O2 are micro-dosed to the suspension by peristaltic pump for 9 min at 0 ° C, once the addition is complete the temperature is maintained and agitation for 12 h. The suspension is filtered and the solid washed respectively four times with water, ethanol and acetone and dried at 70 ° C for 12 hours to obtain an emerald green solid with a 65% yield.

Example 5 Preparation of working electrodes and evaluation of compounds by cyclic voltammetry

Working electrodes were prepared by dispersing 4 mg of PANI-CNN-hematin compound in 1 mL of ethanol / water (1: 1), adding 10 μL of naphion 0.05% by weight as binder. The mixture was dispersed for 15 minutes in an ultrasonic bath, obtaining a homogeneous and stable suspension. He They deposited 10 μL of the suspension on a 3 mm diameter vitreous carbon electrode completely covering the work area avoiding the formation of internal cavities or external remnants. The electrodes coated with the active material are dried at 60 ° C for 60 min. With each material multiple repeats of the electrode were manufactured, statistically ensuring that the measurements were not biased by human error. Cyclic voltametries (CV) were performed with the working electrodes manufactured before, using a Biologic SP potentiostat and a three electrode cell; a platinum wire was used as counter-electrode (CE) and Ag / AgCI as reference electrode (RE), using a 0.5 M H2SO4 solution as electrolyte. The measurements were made within the potential range from -0.2 V to 0.9 V, and sweep speeds from 5 mV / s to 100 mV / s in 10 cycles. Figure 10 compares the cyclic voltametries of the PANI-g-OCN-hematin and NIBP-hematin compounds.

Claims

 Having sufficiently described my invention, I consider as a novelty and therefore claim as my exclusive property, what is contained in the following clauses:

1 A solvothermal process for the preparation of graphitic carbon nitrides with a high content of oxygen and phosphorus, carried out by thermal treatment of urea suspensions with phosphorus pentoxide in different non-polar solvents.

 2. A solvothermal process for the preparation of graphitic carbon nitrides with a high content of oxygen and phosphorus according to claim 1, characterized by using different proportions by weight of urea-phosphorus pentoxide

 3. A solvothermal process for the preparation of graphitic carbon nitrides with a high content of oxygen and phosphorus according to claim 2, characterized in that the weight ratios of urea-phosphorus pentoxide can vary from 10: 1 to 2: 1, preferably using a weight ratio of 4: 1.

 4. A solvothermal process for preparing graphitic carbon nitrides with a high content of oxygen and phosphorus according to claim 1, characterized by using different non-polar aprotic solvents such as hexane, toluene, xylene and other similar

5. A solvothermal process according to claim 1, characterized by using different weight / volume ratios of the mixture of urea-pentoxide phosphorus / solvent wherein these can vary from 10 mg / mL to 200 mg / mL, preferably from 15 mg / mL to 50 mg / mL.

 6. A solvothermal process according to claim 1, characterized by being carried out in closed containers capable of tolerating high pressures and temperatures.

 7. A solvothermal process according to claim 6, characterized by being made in closed containers of stainless steel or titanium, preferably lined internally with non-reactive materials at pH ranges of 1-13.

8. A solvothermal process according to claim 6, characterized by being made in closed containers of stainless steel or titanium, preferably lined internally with non-reactive materials to different solvents under conditions of high temperature and pressure.

 9. A solvothermal process according to claims 7 and 8, characterized in that the internal protection material is Teflon or compounds thereof, such as PPL, capable of tolerating treatment temperatures of 300 ° C and higher.

 10. A solvothermal process according to claim 6, characterized by being made within a temperature range of 200 ° C to 300 ° C, preferably from 230 ° C to 280 ° C and more preferably from 240 ° C to 260 ° C

° C.

11. A solvothermal process according to claim 1, characterized by using different time intervals of preparation, preferably 2 hours up to 24 hours, depending on the reaction solvent and the temperature used.

 12. A solvothermal process according to claim 11, characterized by using different time intervals of preparation, wherein the process preferably takes place in time periods of 4 to 6 hours and more preferably in a space of 4 hours .

 13. A process for the preparation of hematine compounds with graphitic carbon nitrides by depositing hematine on graphitic carbon nitride substrates, characterized by using the materials prepared according to claim 1, generating a suspension thereof in water, adding to the suspension a second suspension of hematin in buffer solutions, combine them for variable times using different mixing systems, separate the compounds generated to finally wash them and dry them to isolate the hematine-graphitic carbon nitride compounds.

14. A process for the use of hematine compounds with graphene nitrides according to claim 13, characterized by using them as catalysts for oxidative polymerization of aniline in aqueous acidic media.

15. A process for the use of hematine compounds with graphene nitrides according to claim 14, characterized in that the pH of the aqueous medium can vary from pH 1 to pH 13, preferably from pH 1 to pH 7 and more preferably have a pH 1.

16.- A process for the preparation of polyaniline-hematin-graphitic carbon nitride compounds by polymerization of aniline using the materials prepared according to claims 14 and 15, characterized in that the pH is regulated by the addition of organic sulfonic acids.

 17. An aniline polymerization process according to claim 16, characterized in using para-toluenesulfonic, dodecylbenzenesulfonic, camphorsulfonic or sulfosalicylic acid to adjust the pH of the suspensions.

 18. An aniline polymerization process using the materials prepared according to claims 14 and 15, characterized by adding aniline to the acid suspensions at low temperature and adding hydrogen peroxide to them.

19. An aniline polymerization process according to claim 18, characterized by slowly adding, with magnetic stirring, hydrogen peroxide solutions at a temperature of 0 ° C to the aniline-compound suspensions maintained at 0 ° C.

 20. An aniline polymerization process according to claim 19, characterized in that a peristaltic pump is used to microdose the slow addition of hydrogen peroxide.

 21. An aniline polymerization process according to claim 20, characterized by maintaining the reactive suspension at 0 ° C for several hours after the addition of hydrogen peroxide is completed to subsequently filter the formed solid, wash and finally Dry 12 hours in an electric oven at 70 ° C.

22.- A process of stabilization of haematin in aqueous media in the entire pH range using binary mixtures of water-organic solvent.

23. A process for stabilizing hematine in aqueous media according to claim 22, characterized by using mixtures of water-dimethyl sulfate in different volumetric proportions.

 24. A process for stabilizing haematin in aqueous media according to claim 23, characterized in that the volumetric ratio of water-

DMSO can vary from 10: 1 to 1: 1, preferably from 5: 1 to 2: 1 and more preferably have a volume ratio of 4: 1.

 25. A hematin stabilization process according to claim 22, characterized by using different proportions of organic sulfonic acids to adjust the pH of the suspensions between pH 1 to pH 7.

 26. A hematin stabilization process according to claim 25, characterized in that the organic acids can be para-toluenesulfonic, dodecylbenzenesulfonic, camphorsulfonic or sulfosalicylic acid.

 27. A process for the manufacture of hematine-polyaniline compounds by polymerization of aniline using the suspensions prepared according to claims 22 to 26, characterized by adding aniline to the acid suspensions of haematin at low temperature and adding hydrogen peroxide to the mixtures. resulting

28. An aniline polymerization process according to claim 27, characterized by slowly adding, with magnetic stirring, hydrogen peroxide solutions at a temperature of 0 ° C to the aniline-compound suspensions maintained at 0 ° C.

29. An aniline polymerization process according to claim 28, characterized in that a peristaltic pump is used to microdose the slow addition of hydrogen peroxide.

 30. An aniline polymerization process according to claim 29, characterized by maintaining the reactive suspension at 0 ° C for several hours after the addition of the hydrogen peroxide is completed to later filter the formed solid, wash and finally Dry 12 hours in an electric oven at 70 ° C.

 31.- A manufacturing process of capacitive and supercapacitive materials characterized by using the polyaniline compounds obtained according to claims 16 and 27 as raw materials for manufacturing.