Strategies For Improving Electrocatalytic Water Splitting Performance Of Cobalt-containing Catalysts

As an alternative for depleting fossil fuel energy,hydrogen economy derived hydrogen production from water splitting has sparked much interest.Precious metals?Pt,Ir,Ru?and its derivative due to their limited reserves and high prices,have greatly restricted the development of the hydrogen economy.The development of cheap,abundant,highly active and durable catalysts for water splitting is of great importance.Based on the current advanced catalyst design strategy,this study explored the effects of doping and interface on the electrocatalytic performance of ceria and cobalt carbonate hydroxide for water splitting.This study has two parts.1.Two-dimensional?2D?ceria nanosheet was produced through a thermal decomposition exfoliation method from CeCO₃OH with a layer-stacked structure.The additional cobalt dopant promotes formation of oxygen vacancies in ceria nanosheet and,in turn,increases the catalytic activity.As a result,the 2D Co-doped CeO₂ nanosheets exhibit an excellent catalytic performance in alkaline HER such that the overpotential is as low as 132 mV to deliver a high current density of 100 mA/cm².Under the same conditions,pure CeO₂ required 301 mV.Such 2D Co-doped CeO₂ nanosheet is also durable HER electrocatalysts,as the activity loss during an extended period of operation is nearly negligible.In OER,only 438 mV overpotential is required to achieve a current density of 100 mA/cm²,which is 94 mV lower than that of pure CeO₂.In addition,in a two-electrode system,bifunctional Co-doped CeO₂ nanosheet electrocatalyst requires only a voltage of 1.84 V to achieve a current density of 100 mA/cm².2.Co?OH?₂/Co?CO₃?_0.5?OH?catalyst was prepared by a two-step synthesis method.The results show that the formation of the interface between amorphous Co?OH?₂ and Co?CO₃?_0.5?OH?promotes the production of OER active species?CoOOH?,increases the electrochemical active surface area,and improves the catalytic activity of OER.At a current density of 100 mA/cm²,the overpotential is 302 mV,which is much lower than IrO₂.In HER,only 304 mV overpotential is required to achieve a current density of 100mA/cm².In addition,the catalytic performance of bifunctional Co?OH?₂/CoCH catalyst is still higher than that of the benchmark catalyst Pt/CllIrO₂.