Preparation Of Micro-and Nano-Inorganic Materials And The Regulation Of Their Electrocatalytic Properties

With the development of human activities and industry business,the demand for energy is growing.The traditional energy mining is getting more and more difficult.There have been emerging many serious problems.Limited reserves are now beginning to become visible.A lot of energy reserves are only a few decades left to explor.On the other hand,the consumption of traditional energy can cause serious pollution of the environment: emissions of carbon dioxide will cause the greenhouse effect;sulfur and nitrogen oxides will results in acid rain and mist,which can cause serious healthy problems.At the same time,the chemical industry itself,especially the organic chemical industry,has attracted more and more attention to the pollution of the environment.Although many countries have spent a lot of money on the pollution control,even in the developed industrial countries,the results are quite limited.People then begin to focus on improving the synthesis process and strengthen management and other measures to eliminate pollution problems,putting forward “the green chemical environmental protection strategy ",that is,the development of clean technology to eliminate the source of pollution.Thus,it is of great practical significance to seek clean energy and green chemistry,where hydrogen is a new secondary energy that people expect from the emergence of conventional energy crises and the development of new secondary energy sources.The ideal new energy of the energetic has many advantages;the organic electrochemical synthesis reaction does not require toxic oxidants and dangerous reducing agents,and the "electrons" are clean reaction reagents.Therefore,in the reaction system,in addition to raw materials and products,usually has no other reagents.Based on the research status and development direction of nanomaterials,this paper discusses the preparation of nanostructures,the preparation and morphology of nanostructures,elemental doping,the regulation of the HER and OER over-potential;through the control of lead dioxide to improve the oxygen evolution potential,thereby enhancing the organic electrification of the current efficiency,the specific work is as follows:?1?By oxidizing the oxide precursors on the carbon nanotubes,the oxides was partially phosphoresized and the core@shell metal@phosphide structure interface catalysts were obtained.For HER,the metal@phosphide core@shell structure and the pure phase phosphide show better HER catalytic performance in acid and alkaline,and the core@shell structure is superior to that of pure phase phosphide.The Fe@FeP/CNT,Co@CoP/CNT and Ni@Ni₂P/CNTcatalysts required 53 mV,67 mV and 114 mV to achieve a current density of 10 mA cm-2,respectively.The performance of the three are among the best of the reported HER catalysts.For OER,at higher positive overpotentials,the phosphide undergoes phase change and is oxidized to the corresponding oxide.Thus,the metal@phosphide structure transfers to a metal@oxide core@shell structure.Our OER test showed that the two had better catalytic performance,but unlike HER,the catalyst with no core@shell structure exhibited higher catalytic activity than the metal@oxide core@shell structure.We used the Fe@FeP/CNT catalyst as an example to illustrate the mechanism of the enhanced electrocatalytic activity by DFT calculation,and to reveal the hydrogen adsorption energy induced by the metal@phosphide electron interaction.?2?We studied the synthesis,solid state chemistry,surface structure and HER electrocatalytic performance of iron phosphide and sulfide nanoparticles grown on CNTs.Two kinds of iron phosphide and sulfide compounds with different crystal structures,adjustable P/S ratio and adjustable electrocatalytic activity were successfully synthesized and characterized.We found that Fe-S sulfide can be FeS or FeP crystal structure,and nanoparticles on the surface rich in P.Although the S atom in the Psubstituted FeS structure greatly increases the HER electrocatalytic activity,the substitution of P in FeP reduces the activity slightly.?3?MoS₂/CNT and MoP/CNT were prepared and the corresponding doping was made.MoS₂|P/CNT and MoP|S/CNT were obtained without changing the structure and phase transition.FeS|P/CNT,the HER performance of MoS₂|P/CNT is greatly improved after the introduction of P element.Compared with FeP|S/CNT,after introducing S element,the performance of MoP|S/CNT is also significantly improved.P atoms with more electronegativity can draw electrons from metal atoms.The charged P can be used as a substrate for capturing a positively charged proton during the electrochemical HER.Thus,for MoS₂ with less active sites exposed,we doped P into its structure,which could increases the active sites.And then greatly improve the HER catalytic activity.?4?The modified Ti/SnO₂-Sb₂O₃/PbO₂ was successfully synthesized.The SnO₂-Sb₂O₃ layer is obtained by thermal decomposition,and the intermediate layer has good conductivity and is capable of well bonding the titanium substrate and the electrodeposited PbO₂ obtained by electrochemical deposition.The oxidation potential of benzene on modified PbO₂ electrode is +1.8 V?vs.Ag/AgCl?.The PbO₂ electrode with a uniform pyramidal structure obtained by electrodeposition can only chemically oxidize benzene to p-benzoquinone with high selectivity.In a 0.5 M sulfuric acid solution containing benzene at a concentration of 0.01 M,the optimum oxidation temperature is 75 ?,and the best oxidation time is 60 min.?5?A PbO₂/SnO₂ NWs/Ti electrode was successfully prepared by hydrothermal method.The electrode has a 3D mesh structure with a high specific surface area.The diameter of a single Pb O₂ particle is about 300 nm.XRD can be seen that PbO₂ is mainly composed of ?-PbO₂ and ?-PbO₂,and the conductivity and catalytic properties of ?-PbO₂ occupied a higher proportion.CV results show that MO can be directly oxidized at a potential of +1.3 V?vs.Ag/AgCl?.Under the condition of room temperature,when the initial concentration MO was 150 mg/L,the optimum pH value was 5.0,and the current density was 15 mA/cm2.After electrochemical degadation for 60 min,the COD remove rate could reach 92.7%.As the prepared PbO₂/SnO₂ NWs/Ti three-dimensional electrode can effectively degrade the methyl orange,which is expected to potentially degrade other organic compounds in aqueous medium.