| Hydrogen energy has the advantages of high energy density,non-polluting combustion products,and wide application range,and is recognized as one of the ideal next-generation energy carriers.Using solar energy and wind energy to produce hydrogen by electrolyzed water is a very important research direction in the field of green hydrogen production.However,the production of hydrogen from electrolyzed water must rely on electrocatalysts,therefore,the development of cheap,efficient and stable electrocatalysts is an effective way to reduce the energy consumption and cost of hydrogen production from electrolyzed water.In recent years,nickel phosphide(Ni2P)has been considered as a potential non-precious metal electrocatalyst due to its structural characteristics like[Ni Fe]hydrogenase.However,some problems such as poor electrical conductivity,poor stability,difficulty hydrolysis in alkaline solution,and weaker Gibbs free energy for hydrogen adsorption make the activity and stability of Ni2P in alkaline solution still unsatisfactory.Aiming at the above problems,nickel phosphide-based composite electrocatalysts were prepared,and its phase,morphology and electrocatalytic performance were studied in this paper.(1)Ni2P-NCNT/CC composite catalysts were prepared on carbon cloth by hydrothermal method and chemical vapor deposition method,which improved the conductivity of Ni2P.The overpotential at a current density of-10 m A·cm-2is 129 m V and the Tafel slope is 95 m V·dec-1,and the hydrogen evolution performance was better than that of Ni-NCNT/CC(163 m V)and Ni2P/CC(155 m V).The impedance of Ni2P-NCNT/CC is smaller.The performance of Ni2P-NCNT/CC did not decrease after3000 cycles of CV and 12 h of continuous hydrogen evolution,it shows better stability.(2)Ni(OH)2/Ni2P/CC composite catalysts were prepared on carbon cloth by three-step method,which improved the hydrolysis of Ni2P in alkaline solution and the adsorption of OH-and oxygen-containing intermediates.Ni(OH)2/Ni2P/CC shows excellent hydrigen evolution reaction(HER)and oxygen evolution reaction(OER)catalytic performance.The hydrogen evolution reaction overpotential at a current density of-10 m A·cm-2is 107 m V and the Tafel slope is 87 m V·dec-1.The oxygen evolution reaction overpotential at a current density of 10 m A·cm-2is 249 m V and the Tafel slope is 45.4 m V·dec-1.The performance of Ni(OH)2/Ni2P/CC was stable after 3000 cycles of CV and after 12 h of hydrogen evolution and oxygen evolution reaction.(3)Ni2P-Ni Se2/CC heterostructure catalysts were prepared by hydrothermal method and chemical vapor deposition method,which reduced the Gibbs free energy for hydrogen adsorption of Ni2P and enhanced the conductivity of Ni2P.The hydrogen evolution reaction overpotential of the Ni2P-Ni Se2/CC catalyst at a current density of-10 m A·cm-2is 66 m V and the Tafel slope is 72.6 m V·dec-1,the oxygen evolution reaction overpotential of the Ni2P-Ni Se2/CC catalyst at a current density of 10 m A·cm-2is 258 m V and the Tafel slope is44.2 m V·dec-1.Ni2P-Ni Se2/CC was assembled as a cathode and anode into a fully hydrolyzed electrolytic cell,the decomposition voltage of the electrolytic cell is 1.54 V at a current density of 10 m A·cm-2and it has stable hydrogen evolution,oxygen evolution,and full water splitting performance. |
PDF Full Text Request