Preparation Of Nickel-based Phosphide Composite Catalyst And Its Catalytic Electrolysis Of Water Performance Research

The technology of electrolysis water to produce hydrogen has the advantages of environment-friendly,simple process,no side reactions and by-product production.However,the existence of potential caused by anode,cathode and other factors greatly reduce the efficiency of electrolysis water.Related literatures reported:transition metal phosphates and corresponding composite catalysts are not only rich in content,cheap in price,but also have higher catalytic efficiency.Therefore,it will be a particularly meaningful scientific research to explore how to further improve their catalytic performance and replace noble metal catalysts,such as Pt/C,RuO2 and IrO2.In this paper,based on three-dimensional?3D?nickel foil or porous nickel foam with good conductivity,the precursors of nickel-based catalysts were obtained by electrodeposition or hydrothermal methods and followed in-situ meteorological phosphorization,a variety of hydrogen-producing or oxygen-producing nickel-based phosphates composite electrocatalysts with unique 3D structures were prepared.I carefully explored the influence of microstructure and composition on the properties of the nickel-based phosphide composite catalysts and analyzed the reasons why the catalytic activity has been significantly increased through diverse physicals and electrical catalytic properties testing,which will help to design and control synthesis electrocatalysts of a series of cheap and high catalytic performance.?1?A novel and direct method was proposed to construct a 3D self-assembled Ni2P nanotubes?FeP@Ni2P/NF?coated with FeP nano-particles on the surface of nickel foil?NF?by two-step electrodeposition and in situ meteorological phosphorization.Its morphology,size,composition and catalytic principle were detailedly studied.Research have shown that Fe P@Ni2P/NF had the best oxygen evolution reaction?OER?catalytic activity compared to pure NF-P nano-particles,Ni2P/NF nanotubes and FeP nano-particles in alkaline electrolyte,only need the potential of 1.52 V to get the current density of 50 mA cm^-2,which is much better than the precious metals RuO₂.Fe P@Ni₂P/NF exhibits optimal OER catalytic activity,possibly for the following reasons:?i?the synergy between FeP and Ni2P facilitates the electron transfer;?ii?the formation of unique ultrathin 3D nanotubes increases the number of active sites and avoids catalyst aggregation during testing.In addition,the effects of reaction conditions on OER electrochemical activity were explored by changing the phosphorization temperature of the precursors.?2?Using nickel foil?NF?as the substrate and by a typical hydrothermal method,3D-self-assembled Fe-doped nickel-based phosphosulphide nanosheet array?FeNiP-S/NF-5?was synthesized by in situ phosphorization and partial sulfurization.At the same time,various physical characterization and electrochemical properties were tested.In addition,the influence of phosphorization temperature and sulfuration time on the hydrogen evolution reaction?HER?property of the material was investigated.The FeNiP-S/NF-5 catalyst showed the best catalytic activity for HER,the potential of 0.183 V can reach the current density of 20 mA cm^-2,which probably because:?i?the 3D nanosheet structure of FeNiP-S/NF-5 can expose more active sites and promote electron transfer;?ii?the synergistic effect between the bimetallic phosphorous sulfide results in its high intrinsic activity;?iii?the sulfurization process further optimize the electronic structure of the FeNiP/NF and inhibit the surface oxidation of FeNiP-S/NF-5 in the catalytic process.?3?A simple and efficient method was proposed to prepare Cu-doped nickel-based phosphosulphide nanosheet array?CuNi S@Ni2P/NF?based on 3D porous NF with a typical one-step hydrothermal method and in situ phosphatization.The influence of different copper doping amount and phosphorization time on the composition and morphology of the product were explored,and the relationship between it and HER were further studied.The results showed that the appropriate amount of copper addition was not only conducive to better maintaining the structure of the nanosheet array,but also affected the degree of from transformation of sulfide to phosphide during phosphorization.At the appropriate amount of sulfide and phosphide,the catalytic activity of HER was optimal.The CuNi S@Ni2P/NF material only require the potential of 144 mV to obtain 10 m A cm^-22 in an alkaline electrolyte,which was mainly due to the addition of appropriate amount of copper effectively optimized the electronic structure of the multi-component and the morphology of the catalyst.?4?W-doped nickel-molybdenum bimetallic sulfide?W-MoS@Ni S?was synthesized by one-step hydrothermal method,followed the W-doped nickel sulfide?Ni3S2?,the molybdenum sulfide?MoS2?and the nickel phosphide?Ni2P?nano-materials composite catalyst?W-MoS@NiS-P-400??were synthesized by in-situ meteorological phosphorization.The effects of the introduction of metallic tungsten on the composition,shape,electronic structure and catalytic performance of bimetallic sulfide nano-materials as well as HER and OER were studied in detail.At the same time,the effects of P on the composition,morphology,electronic structure and catalytic activity of precursor W-MoS@NiS were also carefully characterized.In addition,the influence of phosphorization temperature on the morphology and catalytic activity of catalyst materials were also investigated.Through a variety of characterizations and combined with the composition,shape and catalytic performance of the catalyst,the study shown that the ultra-high double-function performance of W-MoS@NiS-P-400?is mainly attributed to:?i?the doping of W optimizing the electronic structure of MoS@Ni S,improving the conductivity and charge transfer capacity of MoS@Ni S;?ii?the design of 3D nanorods increasing the number of active sites and promoting ion and charge migration;?iii?the interaction between P of introduced in the phosphorization process and W-MoS@NiS precursors stimulated more active sites as well as the preparation and synergistic effect of the ternary metal sulfur phosphates of molybdenum sulfide,nickel sulfide and nickel phosphide.