Study On Catalytic Active Sites Modification And Electrolytic Water Splitting Activity Optimization Of Transition-Metal-Based Electrocatalysts

Transition-metal-based catalysts draw wide attention due to their characteristics of corrosion resistance,high stability,high melting point and high mechanical strength.Consequently,they are used in a variety of energy fields,such as electrocatalysts,catalyst carriers,solar cells and lithium ion battery materials.The advantage of abundant reserves and low cost make them excellent substitutes for noble-metal based water splitting catalysts.Researchers find that effective coupling with other materials or element doping treatment of catalysts can modulate active sites for efficient water splitting.In water electrolysis,the onset potential can be reduced and the current density can be increased by these strategies.Based on above cognition,this dissertation reports two methods to regulate the active sites of catalysts and research the water splitting performance of electrocatalysts which prepared under different synthetic conditions.The main research contents of this paper include the following two aspects:1.The molybdenum mesh as the substrate and sulfur powder as sulfur source synthesize molybdenum disulfide nanosheets grown on molybdenum mesh?MoS₂/MM?by high temperature sulfuration method for free-standing three-dimensional electrode.For the first time,the active sites are regulated by electrochemical anodic activation at positive potentials in H₂SO₄ electrolyte to achieve fast oxygen incorporation into MoS₂ within 200 seconds,leading to the good hydrogen evolution reaction performance.The process of oxygen atom doping into MoS₂ is studied in detail.The results of electrochemical measurement indicate that Oxygen-incorporated MoS₂?O-MoS₂/MM?possess excellent catalytic activity with low onset potential and good durability.The DFT calculations confirm that O atoms doping produce more charge carriers and more active sites of MoS₂ with tuned free energy change of absorbed hydrogen,and lead to the enhanced hydrogen evolution reaction activity effectively.This work paves a simple,fast,controllable and universal pathway for improving the electrocatalytic activity by electrochemical anodic activation process,which is successfully applied to MoS₂,MoSe₂ and Mo P for hydrogen evolution reaction.2.The environmentally friendly in situ green phosphating strategy and spatial limiting effect of the RuCo precursor are employed to fabricate the ruthenium nanoclusters anchored on cobalt phosphide hollow microspheres?Ru NCs/Co₂P HMs?.The optimum conditions,formation mechanism and electrolytic water properties of the Ru NCs/Co₂P HMs were studied.The as-obtained Ru NCs/Co₂P HMs electrocatalysts exhibit high hydrogen evolution reaction activity at wide p H ranges and good oxygen evolution reaction activity in acid electrolyte.A two-electrode electrolyzer is assembled by hiring Ru NCs/Co₂P HMs as both cathode and anode.In acid electrolyte,its water splitting performance is superior to that of the benchmark of precious metal-based electrolyzer.This work elucidates the effect of electron transfer between Co₂P and Ru nanoclusters on regulating active sites.