Design, Synthesis And Comprehensive Water Splitting Performance Of Cuprous Phosphide-layered Double Hydroxid

Hydrogen energy is widely considered as a promising clean energy source because of its various advantages such as sustainability,environmental friendliness,high energy density and the possibility of long-term storage.Overall water splitting(OWS)is one of the most attractive methods in the current hydrogen production process.The development of bifunctional electrocatalysts with high catalytic activity,favorable stability,low cost and high metal abundance is a necessary prerequisite for overall water splitting.Noble metal catalysts(e.g.,Pt-based,Ir-based)have excellent OER or HER performance,but their high cost and energy scarcity limit their large-scale use.Therefore,it is essential to design an electrocatalyst that is abundant,inexpensive,efficient and able to catalyze both OER and HER,especially under alkaline conditions.Transition metal phosphides(TMPs)are known to be ideal electrocatalysts due to the metal-like properties,excellent electrical conductivity and stability,but they have to overcome the drawbacks of few active sites and limited specific surface area.Layered double hydroxides(LDHs)are twodimensional materials with special morphology and high electrocatalytic activity,which have received increasing attention for the high abundance,easily adjustable composition,and large specific surface area.Therefore,it is suggested that is an effective strategy to promote OWS by coupling TMPs with LDHs to fabricate heterostructured catalysts.The main research of this paper is as follows:Cu3P@CoFe-LDH/CF heterostructured electrocatalysts was constructed by a simple two-step electrodeposition strategy.It was demonstrated by XPS that electrons flow from CoFe-LDH to Cu3P and there is a strong interfacial interaction between the two.Due to the synergistic interaction between the two phases,the catalyst has excellent catalytic performance for overall water splitting.It was shown that the overpotential of the catalyst was 331 mV for OER and 205 mV for HER at a current density of 100 mA cm-2.Then,the Cu3P@CoFe-LDH/CF catalyst was used to form a two-electrode device,which required only 1.56 V to achieve a current density of 10 mA cm-2.Ni2P-Cu3P@CoFe-LDH/CF heterostructured catalysts was designed by the same two-step electrodeposition strategy.It was shown that the doping of nickel phosphide improved the electrocatalytic performance of the material.The addition of nickel element increases the Cat-OH bond strength and facilitates the intermediate adsorption in the Volmer step.Compared with monometallic phosphides,bimetallic phosphides provide bidirectionally abundant active centers with superior electrocatalytic performance.The overpotential of the catalyst was 287 mV for OER and 196.5 mV for HER at a current density of 100 mA cm-2.The catalyst was constructed as a two-electrode device,which required only 1.438 V to achieve a current density of 10 mA cm-2.A heterostructured catalyst with the growth of CoFe-LDH nanosheets on Cu3P nanorods was designed and synthesized using an oxidation-phosphorizationelectrodeposition strategy to modulate the morphology of Cu3P@CoFe-LDH/CF.The catalyst exhibited excellent activity and stability both in OER and HER.The overpotential of this catalyst was 293 mV for OER and 181.4 mV for HER at a current density of 100 mA cm-2.In addition,the alkaline electrolyzer of Cu3P@CoFe-LDH/CF‖ Cu3P@CoFeLDH/CF shows low cell voltage of 1.452 V@10 mA cm-2 for OWS.The excellent performance may be attributed to the electronic coupling between the two interfaces of the multiphase electrocatalyst,with Cu3P providing a well-conducting backbone and CoFe-LDH providing a large specific surface area and an abundance of active sites.