Preparation Of Cobalt-based Nanocatalyst And Its Electrochemical Water Splitting Properties

Global climate change and energy crisis have made the development of new sustainable and clean energy a research hotspot in various countries.Hydrogen has the advantages of high energy density,green and pollution-free,and has become an ideal alternative to traditional fuels.However,the technology of electrolysis water to produce hydrogen consumes a lot of energy and is restricted by the slow kinetic process in electrolysis,so its large-scale industrial application is limited.The research and development of high performance and cheap non-noble metal catalysts is the key to solve this problem.In this paper,based on the application of cobalt-based catalyst in electrochemical water splitting,a composite electrocatalyst of cobalt-based compound and nitrogen-doped carbon material was constructed,and the structure and catalytic activity of the catalyst were systematically analyzed.The main content includes the following two parts:1.Facile synthesis of CoSe nanoparticles encapsulated in N-doped carbon nanotubes-grafted N-doped carbon nanosheets for water splittingTransition metal selenides have high electrochemical activity and abundant earth reserves.They are excellent electrocatalysts for electrochemical water splitting.Carbon materials have the advantages of large surface area,good electrical conductivity,and effective prevention of catalyst particle agglomeration.Therefore,a three-dimensional composite catalyst of CoSe nanoparticles encapsulated in N-doped carbon nanotubes-grafted N-doped carbon nanosheets was prepared by one-step pyrolysis.The three-dimensional network structure provides a larger surface area,the as-prepared material shows excellent catalytic activity in 0.5 M H₂SO₄ solution(the overpotential of 197 mV at 10 mA cm^-2 for HER).At the same time,excellent OER activity was demonstrated in a 1M KOH solution with an overpotential of 301 mV and a Tafel slope of 75 mV dec^-1 at a current density of 10 mA cm^-2.The catalyst has good electrocatalytic performance,which is comparable to most cobalt-based electrocatalysts reported in the past.The synthesis of materials has low toxicity and simple process,which can be widely used in the synthesis of other transition metal selenides.2.Synthesis of metal phosphide nanoparticles supported on porous N-doped carbon derived fromspirulina foruniversal-pH hydrogen evolutionTransition metal phosphide?TMPs?is considered to be a highly active electrocatalyst for HER.However,traditional synthetic routes often use expensive and dangerous precursors as P sources.Therefore,the development of a low-cost and environmentally friendly method to synthesize TMPs is of great significance to the sustainable development of energy.In this paper,cobalt phosphide loaded or embedded on porous nitrogen-doped carbon materials?Co₂P-NC?derived from biomass was prepared by two-step hydrothermal and high-temperature pyrolysis,and carbon,nitrogen and phosphorus from biomass itself were used as C,N and P sources.Due to the large surface area and abundant porosity of Co₂P-NC,which is conducive to the exposure of the active site and the contact between the catalyst and the electrolyte,Co₂P-NC shows good HER activity at the all pH value.This work not only makes full use of the essential elements of biomass to prepare biomass-derived carbon materials,but also provides a new idea.