Study On Heteroatom Doping Modification Of Nano-Lamellar Transition Metal Compounds And Their Properity Of Water Splittng

With the rapid development of economy and technology,the social demand for energy is deepening.The consumption of traditional fossil energy and environmental problems caused by burning need to be solved urgently.Therefore,it is essential to develop a clean and renewable alternative to fossil fuels.Among alternative energy sources,the construction of energy infrastructure that hydrogen as the main carrier links a large number of energy sources to various end-uses,can achieve a safe and clean energy future.Hydrogen production from electrochemical water splitting is a method of directly converting electric energy into hydrogen energy and has the characteristics of high efficiency and pollution-free.It is a promising technology for hydrogen production.Due to the existence of dynamic energy barrier in the transmission of electrons in the process of water splitting,the applied voltage in the actual process of water splitting is higher than the theoretical voltage,which greatly decreases the overall efficiency of the electrolytic water system.Therefore,reducing the overpotential in the process of electrolytic water is the focus of current research in the field of hydrogen production from electrolytic waterIn this paper,the catalytic activity of nano-lamellar transition metal compounds for hydrogen evolution reaction(HER)or oxygen evolution reaction(OER)has been improved by heteroatom doping modification.Using hydrazine oxidation reaction(HzOR)with favoratable thermodynamics instead of OER as the anodic reaction achieved the improvement of hydrogen production efficiency in electrolysis of water.The main contents are as follow:1.P-CoCO3/CF used as highly-efficient electrocatalyst for energy-efficient hydrogen production.We first prepared CoCO3 nanosheets on the cobalt foam through hydrothermal method.Then,the doping of P was achieved by annealing of CoCO3 nanosheets.The prepared P-CoCO3/CF exhibited excellent HER,OER and HzOR catalytic performance.In 1 M KOH,to reach a current density of 10 mA cm-2,P-CoCO3/CF only needs overpotentials of 46.1 mV for HER and 275 mV for OER.Using P-CoCO3/CF both as cathode and anode combined a two-electrode electrolysis system,which requires a cell voltage of 1.77 V to reach a current density of 100 mA cm-2.In 1 M KOH with 0.3 M N2H4,potential only-42.3 mV vs.RHE is needs to deliver an anode current of 100 mA cm-2 for HzOR.The two-electrode system prepared by using the thermodynamically favorable HzOR instead of OER as the anode reaction shows a more efficient hydrogen evolution efficiency.To reach a current density of 100 mA cm-2,only 0.13 V cell voltage is needed.At the same time,the system shows a excellent stability.After 18 hours of stability test with a current density of 50 mA cm-2,the required voltage of the system increases by only 59.2 mV.2.Fe-doped a-Ni(OH)2 and p-Ni(OH)2 used as highly efficient electrocatalytic couples for overall water splitting.Fe-doped a-Ni(OH)2 and p-Ni(OH)2 were prepared by one-step hydrothermal method.Fe can induce the formation of a-Ni(OH)2 at 120 ℃.Fe-doped a-Ni(OH)2-120 exhibits excellent OER performance and excellent stability.In 240 ℃,Fe will induce the formation of p-Ni(OH)2.Fe-doped β-Ni(OH)2-240 exhibits excellent HER performance for the first time.The excellent HER properties of Fe-doped β-Ni(OH)2-240 can be attributed to the inherent HER properties of β-Ni(OH)2 and the doping of Fe.An efficient hydrogen production system was prepared by using Fe-doped a-Ni(OH)2-120 as anode and Fe-doped p-Ni(OH)2-240 as cathode.To reach a urrent density of 10 mA cm-2,only 1.54 V of cell voltage is needed.At the same time,the electrolytic system showed robust stability.