Preparation And Electrochemical Performances Of Cobalt-based Bifunctional Catalysts For Overall Water Splitting

Electrocatalytic water splitting has been proposed as a promising solution to solve the increasing serious energy crisis and environmental pollution issue.However,the high overpotentials and slow kinetics of two half reactions?HER and OER?restrict the efficiency of overall water splitting.Precious metal catalyst,such as Pt and IrO₂/RuO₂ can effectively reduce the overpotentials of HER and OER,but their scarcity and expensive price limit their large scale application.Hence,developing efficient and stable non-noble metal catalysts to promote the efficiency of water splitting is necessary.In recent years,cobalt-based compounds have attracted the attention of researchers due to their diverse and simple preparation methods,but there are few reports for cobalt-based bifunctional catalysts for both HER and OER.In this article,we will focus on synthesize cobal-based phosphide and selenide with different structures by different methods and explore their properties of water splitting.The main research contents are as followings:?1?We prepared a ternary phosphide Mn-Co-P with yolk-shell structure by a rational design and studied the effects of different tempertures on morphologies,structures and properties.The overpotentials of Mn-Co-P microspheres under optimal conditions are 66 mV and 306 mV at a current density of 10 mA cm^-2 for HER and OER,respectively.In addition,the excellent performances of HER and OER are attributed to the unique yolk-shell structure which increased the contact area with electrolyte and the synergistic effect between Mn and Co.?2?We synthesized the Mn-doped CoSe₂ supported on nickel foam by using the metal organic framework?MOF?with porous and large specific surface areas as template.The synthesized Mn-CoSe₂/NF material shows good HER and OER performances,when functioning as both the cathode and anode for overall water splitting,a low cell voltage of 1.75 V is need to achieve the current density of 50 mA cm^-2.More importantly,the Mn-CoSe₂/NF material can well maintain initial morphologies after electrolytic processes,suggesting the outstanding stability.