Research Co-based Catalysts In Deep Eutectic Solvents By Electrodeposition And Their Performance Of Water Splitting

Hydrogen energy as an environmentally-friendly energy is drawing more and more attention.Water splitting for H₂ is a well-resourced and green process.While,the dynamic barrier for water splitting leads to a much larger overpotential to carry out this process.The use of noble metals with excellent performance towards water splitting is hindered by their reserve scarcity and high price.Developing transition metal cobalt oxide and phosphide for overall water splitting has gained widespread attention.Catalysts from electrodeposition method can keep their morphologies and performances.Deep eutectic solvents?DESs?with wide electrochemical window,low vapor pressure,good conductivity and facile preparation routes,are promising to replace corrosive and complex to prepare plating baths.Meanwhile,they are biodegradable,and less corrosive.In this article,we used DESs to dissolve Co and P salts to electrodeposite catalysts on Ni foam at the nucleation potential.In different DESs with a series ratios of Co and P,we got catalysts and explored their performances towards HER and OER.When the ratio of Co and P was 1,the 1P-Co@NF showed the best performances.It only requires 62 mV and320 mV overpotentials to reach 10 mA/cm² for HER and OER.This mainly ascribed to the well-dispersed catalyst on Ni foam,relative more active sites and low resistance.The physical properties of 1P-Co@NF were further explored.It is revealed that1P-Co@NF is a composite of Co₃O₄ and Co₂?P₂O₇?,which are nanoparticles and they further formed larger nanoparticles grown onto Ni foam.When used for water splitting,1P-Co@NF can reach 10 mA/cm² at the voltage of 1.59 V.In addition,1P-Co@NF shows an excellent stability during 24 h continuous stability test.The electrodeposition route can strengthen the combination of catalyst and substrate,and lead to a uniform dispersion of catalysts on Ni foam for lack of binders.