Design,Preparation And Performance Regulation Of Carbon-Based Metal Composite Electrocatalysts For Hydrogen Evolution

In view of the current energy crisis and environmental pollution,the development and utilization of new energy are considered as the primary choice to solve the above problems.Hydrogen energy with the advantages of high energy calorific value,green and pollution-free,is a potential energy source.Water electrolysis combined with renewable energies is an efficiency and green hydrogen production method,which can be to realize simple and controllable hydrogen production for broad application prospects.Two reactions are involved for hydrogen production from water electrolysis:hydrogen evolution reaction（HER）and oxygen evolution reaction（OER）.Due to the high hydrogen evolution overpotential and sluggish hydrogen evolution kinetics at the electrode surface,the efficient electrocatalyst usually needed to promote the electrocatalytic reaction.At present,precious metal platinum（Pt）based catalysts are widely studied because of their excellent catalytic activity,but their large-scale application is limited by scarce storage and high price.In addition,although nano-catalysts have a high catalytic activity,the agglomeration,fall off and corrosion issues during catalysis process severely restrict their applications.Therefore,the present research focus is on creating catalysts with a stable structure,superior functionality,and affordable costs.Ru with good catalytic activity and cheap cost is deemed a possible alternative to Pt.In addition,carbon material with the qualities of the large surface area,strong conductivity,and stable structure,combined with the nano-catalyst can effectively solve the above nano-catalyst’s current issues.In this paper,carbon materials with different morphologies and structures are designed and prepared to form composite catalysts with Ru/Ni/Co nanoparticles to catalyze HER.The specific research contents are as follows:（1）Reduced graphene oxide@mesoporous N-doped carbon nanosheets（r GO@MNCs）is prepared by the molecular-mediated interfacial co-assembly strategy.Then,Ru Ni NPs are confined in the mesopores of r GO@MNCs by impregnation and hydrogen reduction processes.Benefiting from the uniform dispersion of Ru Ni nanoparticles and the large specific surface area of N-doped carbon maxtri,the Ru Ni-r GO@MNCs-2 catalyst exhibits overpotentials of 28and 37 m V(j=10 m A cm^-2),and Tafel slopes of 35 and 54 m V dec^-1 in alkaline and acidic solutions,respectively;（2）A metal-organic framework material（3DOM ZIF-67）with a three-dimensional ordered macro-microporous structure is prepared by the precursor@template and two-solvent methods.Subsequently,3DOM ZIF-67 is subjected to high-temperature pyrolysis,air oxidation,low-temperature phosphating,and impregnation reduction to prepare a 3D ordered macro-porous Ru-Co P composite electrocatalyst（3DOM Ru-Co P@NC）.Compared with Ru-Co P@NC,3DOM Ru-Co P@NC shows better catalytic activity with the overpotential of 15 and 45 m V at a current density of 10 m A cm^-2,and the Tafel slopes of 38 and 50 m V dec^-1 in alkaline and acidic solutions,respectively.The better catalytic activity is attributed to the exposure of more active sites in the3D ordered interconnect nanospace,the doping of N atoms improves electron transport,and the synergistic catalysis of Ru and Co P;（3）The ultrafine Ru X₂ nanoparticle supported on flower-like N-doped carbon nanospheres is prepared by two-step template method and in situ vulcanization and selenization processes.In addition,the catalytic performance of the catalyst under different electrolyte conditions is investigated.The as-prepared Ru S₂@FNCs catalyst exhibits low overpotentials of 31 and 48 m V at10 m A cm^-2 in alkaline and acidic media,and Tafel slopes of 56 and 61 m V dec^-1,respectively.The good catalytic performance is attributed to the flower-shaped carbon spheres providing more areas for the dispersion of active nanoparticles,and S as an additional active center promotes the electrocatalytic reaction;（4）Ru combined Co/N-doped CNT/reduced graphene oxide framework（Ru-Co/NCNT/r GO）is prepared by template self-sacrifice method and in-situ reduction strategy for HER catalysis.The Ru-Co/NCNT/r GO catalyst shows good catalytic activity with overpotential of 24 and 49 m V at 10 m A cm^-2,and Tafel slopes of 38 and 42 m V dec^-1,respectively,in alkaline and acidic electrolytes.The stable porous NCNT/r GO framework promotes electron migration and material transport,and inhibits the fall off and corrosion of metal particles.In addition,the synergistic effect between the uniformly dispersed Ru and Co nanoparticles promotes the electrocatalytic reaction.