Preparation Of 2D Material Supported Cobalt-based Catalysts & Their Applications In Electrochemical Water Splitting

Fossil fuels are the main energy sources in today’s world,but the energy crisis caused by their depletion and the environmental pollution caused by combustion have become an important issue that need to be solved urgently.Therefore,hydrogen as a clean and renewable energy has become a hot topic for researchers.Electrolytic water hydrogen production technology has advantages of high efficiency and no pollution,and is considered to be a mature and feasible way of hydrogen production.However,the most efficient catalysts for hydrogen production are noble metal catalysts with high cost and low reserves,which difficult to be widely used.Therefore,the development of a non-noble metal electrocatalyst with good performance,low price and abundant reserves is of great significance for the practical application of electrocatalytic hydrogen production technology.Therefore,this paper is based on the development of 2D material supported non-noble metal cobalt-based catalyst on high active surface,and its system is applied to the electrochemical catalytic hydrogen production process.The main contents and results of the study are as follows:A unique preparation process was designed to prepare carbon-coated Co/Co₉S₈–Mo S₂ non-noble metal catalyst.It was found that excessive H₂S produced during the decomposition of the precursor ammonium sulphobolybdate can partially sulfurize carbon-coated Co nanoparticles,and Co/Co₉S₈mixed phases will be form on the Mo S₂,and the as-prepared catalyst possesses good bifunctional electrocatalytic activity under alkaline environment for HER and OER.The amorphous carbon-coated Co/Co₉S₈–Mo S₂ composite shows low overpotential of 128 m V for HER and 325 m V for OER in 1 M KOH solution,respectively,and have a low Tafel slope.The cell voltage of the electrolysis process is 1.69 V.Systematic analysis showed that the enhanced reactivity was mainly due to the strong interaction and synergy between Co,Co₉S₈ and Mo S₂.Besides,the amorphous carbon shell can prevent Co/Co₉S₈nanoparticles from corrosion and improve their cyclic stability.Aiming at the key problem of the influence of the overall conductivity of electrocatalysts on the hydrogen production process,a new Co/Co P–Ti₃C₂T_x Mxene composite catalyst was prepared by low temperature phosphating method,using two-dimensional material MXene with excellent electrical conductivity as the carrier.Study found that,due to the existence of carbon shells,part of Co nanoparticles were phosphated to form Co/Co P composite particles.Through electrochemical performance test,Co/Co P–Ti₃C₂T_x catalyst has high HER activity and low Tafel slope under alkaline conditions.The results show that the heterojunction formed by cobalt and semiconductor Co P can improve the performance of hydrogen evolution.In addition,Ti₃C₂T_x nanocrystals can accelerate the electron transport process,and the stability is improved by the presence of the surface carbon shell.