Preparation Of Ni_xM_1-x（M=Fe,Co）（P,Se₂）/Nitrogen-doped Carbon Three-dimensional Electrodes And Their Electrocatalytic Performance For Water Splitting

Hydrogen as a green renewable energy source has been widely researched.Water electrolysis is not only an important way to produce hydrogen,but also simple,no pollution in process and can be reused.However,developing effective electrodes material is indispensable to decrease electrolysis of water consumption.Effective electrodes material should have good electrical conductivity,large specific surface area,highly catalytic activity and good stability.Transition element Ni（3d⁸4s²）is an excellent electrodes material.Besides,bimetallic can optimize the valence of natal and electronic state to improve catalytic performance.Nitrogen-doped carbon nanotubes（NCNT）and three-dimensional network NiCo@nitrogen doped graphene（NGF）as the supporters can increase the load and conductivity.this paper constructs Ni_x Fe_1-x-x Se₂/NCNT three-dimensional nanometer array catalyst as anode oxygen evolution material.Simultaneously,developing a three-dimensional network porous Ni_xCo_1-xP@NGF catalyst as cathode hydrogen evolution material.1.Ni_xFe_1-x-x Se₂/NCNT:preparation and application in OERThe FeOOH was grown on the carbon cloth by hydrothermal method,and the three-dimensional carbon nanotube array was catalyzed.NiFe bimetallic hydroxides(Ni_xFe_1-x（OH）₂)are deposited on the surface of the three-dimensional nitrogen-doped carbon nanotube arrays by electrodeposition.and selenizing to be the composite catalyst.Changing electrodeposition time to regulate the deposition amount,Studying the influence of the deposition amount for the catalytic performance.For the deposition time of 30 min selenide,The reversible hydrogen overpotential is 1.548 V when the current density is 100 mA·cm^-2.The relative current density of Ni_x Fe_1-x-x Se₂/NCNT dropped to 96.6%after working 9 h.under the same conditions,The addition of Fe element can improves the oxygen evolution performance.The Fe element is more suitable for improving the catalytic performance than the Co element,because the Fe element doping can promote the formation of metal oxide and improve the performance.As for the carrier,NCNT is more suitable than carbon cloth,Besides,The three-dimensional carrier of NCNT can enhance the material loading and improve the ionic and charge transport properties of the electrode material,which can greatly improve its oxygen evolution2.Ni_xCo_1-x-x P@NGF:preparation and application in HERThe NiCo foam was treated with dilute hydrochloric acid to remove the impurities on the surface.A layer of porous NGF wrapping NiCo foam by chemical vapor deposition（CVD）.The temperature of growing graphene is changed at 600℃、700℃、800℃and900℃to determine the best growth temperature.Phosphorization is carried out to obtain a series of(Ni_xCo_1-x-x P@NGF)_t（t is the growth temperature/℃）.The results show that the(Ni_xCo_1-x-x P@NGF)_800℃is the best material which reversible hydrogen overpotential is-0.107V when current density is 10 mA·cm^-2.The relative current density of Ni_xCo_1-x-x P@NGF dropped to 90%after working 9 h.It was also found that the NiCo-based electrode material exhibited better hydrogen evolution properties than Ni foam because of the optimization of the valence state and electron cloud state of the metal element.Besides.The urea is better than methane to grow graphene.The nitrogen-doped porous graphene has better conductivity and electrochemical performance than ordinary graphene.