Nickel Foam Supported Cobalt Nickel Phosphide And(Hydr)oxide Catalysts For Photo-electrochemical Hydrogen Evolution Reaction

With the rapid economic development,the shortage of energy is getting worse,the development of a new kind of green energy has become an important way to mitigate the energy crisis.As a kind of clean and sustainable energy,hydrogen energy has gradually attracted the attention of researchers because of its high energy density and easy preparation.Electrocatalytic water splitting and electro-photocatalytic water splitting are two efficient means for hydrogen evolution.The catalyst is one of the key factors to determine the efficiency of hydrogen evolution,as we all know,Pt and its alloys exhibit lowest overpotential and best catalytic activity,however,the high prices,low reserves limit their large-scale industrial application.Cobalt nickel-based compounds,with the advantages of low cost,large reserves,excellent catalytic activity and long-time stability,can be used as an alternative for precious metal catalysts.In this paper,the structural design and synthesis conditions of cobalt nickel phosphide>oxide and hydroxide nano-catalyst are optimized,to reduce the energy barrier of electrochemical water splitting and improve the catalytic activity of hydrogen evolution.In this paper,the synthesis condition of cobalt nickel phosphide was explored,CoP nanowires and Ni2P nanosheets arrays were successfully prepared on the nickel foam substrate by hydrothermal and phosphidation treatment.We adjusted the reaction time and temperature and Co2+/Ni2+ratio of precursor to investigate the effects of these factors on electrocatalytic activity.The porous array structure of the CoP-Ni2P binary composite not only facilitated the transportation of electrons between the nickel foam and the nano-catalyst,but also maximized the electrochemically active surface area,to expose more active sites in the electrolyte.The fabricated CoP-Ni2P/NF catalyst showed excellent electrocatalytic activity,it only required 48 mV and 147 mV to acquire the current density of 10 mA cm-2 and 100 mA cm-2,respectively,in 1 M KOH solution,which is significantly better than most non-precious metal catalysts.Co3O4-Ni(OH)2/NF nano composite were successfully prepared on the nickel foam substrate by hydrothermal and high temperature dehydration oxidation treatment.HRTEM,together with XPS,was employed to analyze the morphology and structure,UV-visible spectrophotometer and photoluminescence were employed to analyze the optical performance.The junction structure of Co3O4 and Ni(OH)2,on the one hand,utilized the synergistic effect to improve the catalytic activity of electrocatalyst for hydrogen production,on the other hand,the as-formed p-p type semiconductor reduced the combination of photo-induce electron and hole pairs and accelerated the electrons transport for photocatalytic hydrogen evolution.Under the bias of-0.2 V vs RHE,the light response current density of Co3O4-Ni(OH)2/NF was enhanced to 1.11 mA cm-2,exhibiting excellent photo-electrocatalytic activity.