Construction Of Molybdenum-based Electrocatalytic System And Study On Hydrogen Evolution Performance

The rapid development of human civilization makes people increasingly dependent of fossil energy,overuse aggravates environmental pollution and global warming,seeking a new green energy carrier is one of the most challenging problem in modern world.Hydrogen energy has attracted extensive attention because of its cleanliness,renewable ability and high energy density.With the rapid development of solar and wind power generation,the photovoltaic industry and wind power generation industry have been vigorously promoted in the northwestern region.Due to the intermittent and fluctuation characteristic of solar and wind power generation,which is limited by space and time factors,the power output is not stable.The combination of electrochemical decomposition water with unstable renewable energy can realize the efficient utilization and conversion of unstable energy.Exploiting for highly efficient electrocatalysts is the core challenge of water electrolysis technology.At present,precious metal catalyst Pt/C is the main catalyst which used in the process of hydrogen evolution from electrolytic water.However,the low reserves and high cost of precious metals seriously hinder its large-scale application.Transition metals,due to its physical and chemical properties,are considered to be the most likely catalyst to replace precious metals and realize mass production,which has attracted extensive attention from researchers.Based on this,this subject mainly oriented to improve the performance of hydrogen evolution electrode as the guide,utilizing interface engineering to rationally design of the molybdenum-based catalyst,and study electrocatalytic performance.In this paper,the structure-activity relationship between the construction of metal-semiconductor Mott-Schottky heterojunction and the catalytic performance of the electrode material is studied,and the mechanism of the influence of the heterogeneous interface on the electron transport of the catalyst is analyzed,which improves the electron conductivity of the electrode.By constructing the crystalline and amorphous mesogenic interface on the surface of the electrode,investigate its effect on the catalytic properties,crystalline and amorphous analyzed the role of the mass transfer process electrocatalytic process.The detailed contents of this paper are as follows:（1）Research on the promotion of electron transport by the construction of transition metal-semiconductor Mott-Schottky heterostructure.In order to solve the problem of few active sites,poor conductivity and limited synthesis methods of the transition metal intrinsic in the electrocatalytic hydrogen evolution reaction,it is proposed that a strategy to adjust the composition and structure of the electrode.The Mo@（2H-1T）-Mo Se₂ monolithic electrode is prepared through in-situ etching of molybdenum mesh in Na₂Se O₃ solution,successfully forming the Mott-Schottky heterojunction.Continuous phase and morphology modulation of Mo Se₂ is realized by controlling the reaction condition.The heterogeneous interface provides abundant active sites and accelerates electron transfer rates,which exhibits excellent electrocatalytic activity and universality in acidic,alkaline,neutral and seawater solution systems.Due to the simplicity and expandability of in situ etching method,the area of the monolithic electrode can be expanded arbitrarily and the Ni,Cu and W mesh can also be used to construct monolithic electrodes with excellent HER performance.This work presents a generic approach to design a series of effective monolithic electrodes for achieving large-scale industrial production.（2）Research on the construction of crystalline and amorphous synergistic catalytic mesogenic interfaces on the electrode surface enhances the electron transport process.In order to improve the material transfer efficiency in the electrocatalysis process,a synergistic catalytic interface between crystalline Ni（OH）₂and amorphous Ni Mo S was constructed on Ti mesh.The synergistic reaction mechanism and the vital role of crystalline Ni（OH）₂ and amorphous Ni Mo S were accurately elucidated by acid etching and calcination treatments.In acidic solutions,the HER performance of Ti@Ni（OH）₂-Ni Mo S is mainly attributed to the amorphous Ni Mo S,while in neutral,alkaline and natural seawater,the HER performance is mainly determined by the synergistic interface behaviors between the Ni（OH）₂ and Ni Mo S.Specifically,the crystalline Ni（OH）₂ promotes water dissociation kinetics and the amorphous Ni Mo S obtained by crystalline transformation serves as a reaction platform to provide abundant active sites and superior electron transfer rates.The abundant active sites and superior electron transfer rates were verified by electrochemical surface area（ECSA）and Electrochemical impedance spectroscopy（EIS）.The HER kinetics in acidic,neutral,alkaline solutions and natural seawater are excellent along with electrochemical transformation process during sulfuration.This study establishes Ti@Ni（OH）₂-Ni Mo S electrocatalyst as a highly competitive candidate for electrochemical water splitting and provides general guidelines for designing efficient hydrogen evolution systems in all-p H range and natural seawater.