Construction Of Co-based Nitrogen-doped Carbon Nanotubes Materials And Electrocatalytic Performance For Water Decomposition

Since the first and second industrial revolutions,new inventions and technologies have brought great convenience to modern society,most advanced technologies rely on carbon-based fuels such as coal,natural gas,and petroleum.The depletion of these limited resources and their environment-hagardous effect have motivated a variety of researchers to pursue alternative energy.Hydrogen production from water electrolysis is one of the most important technologies to solve energy crisis and environmental problems.Water electrolysis are two-electrode systems,where the cathode part involves hydrogen evolution reaction(HER)and the anode part proceeds with oxygen evolution reaction(OER).However,one of the important reasons that keeps these systems from being of widely practical application is the sluggish kinetics reaction.In the past several decades,precious Pt-based and Ir/Rubased electrocatalysts have been usually employed in driving the electrochemical reactions of practical water electrolysis to reduce the activation energy barriers of HER and OER,respectively.Unfortunately,the large-scale utilization of these noble metals has been severely blocked by their limited abundance and high cost.In light of inspiration mentioned above,we taken an easy-manipulated template cobalt based urea complex as staring catalyst,and obtained cobalt-based carbon nanotube composite materials by heating under inert gas atmosphere,and study its applications as a catalyst in the electrolysis of water.The work contents of this paper are as follows:1.Cobalt ions combined with nitrogen-containing urea ligands to form precursor cobalt based urea complex by a simple method,which were mixed with ethanol solutions of H2PtCl6 and heated at high temperature,then nitrogen-doped carbon nanotubes encapsulating PtCo alloys(PtCo/NC).Among them,PtCo/NC-600 exhibited excellent HER catalytic performance and stability in both acidic and alkaline media.At current densities up to 10 mA cm-2,the HER overpotential of PtCo/NC-600 in acidic media is 22 mV and that of PtCo/NC-600 in alkaline media is 34 mV,lower than that of commercial Pt/C.Additionally,PtCo/NC-600 exhibited good stability in long-term stability tests.2.Cobalt based urea complex precursors and transition metal ions M2+(M=Fe2+/Ni2+/Mn2+)were dispersed in ethanol solution,followed by a two-step programmed heating process to obtain nitrogen-doped carbon nanotubes encapsulating cobalt-based polymetallic alloy/oxide nanoparticles(CoM@CNTs).The CoNiFe/MnO@CNTs exhibited good HER and OER electrochemical properties and stability in alkaline media.At current densities up to 10 mA cm-2,CoNiFe/MnO@CNTs exhibited an overpotential of 122 mV for HER and 275 mV for OER,also showed excellent stability during voltammetric cycling and constant current stability tests.