Study On Structural Regulation And Electrochemical Properties Of Ni/Fe Based Electrocatalytic Materials

With the rapid development of the economy,the development and use of large amounts of fossil energy have led to deteriorating environmental problems,and the development of green,efficient,renewable,and clean energy sources to replace traditional fossil energy sources is now a growing concern.As a clean energy source,hydrogen is an ideal alternative to fossil fuels due to its renewable and non-polluting properties.Hydrogen production by electrolysis of water is one of the most effective methods to obtain high-purity hydrogen,consisting of two half-reactions:hydrogen precipitation at the cathode and oxygen precipitation at the anode.At this stage,precious metal electrocatalysts are currently the most efficient electrocatalysts available,but their high and scarce reserves limit their development for practical applications.Low-cost,widely distributed 3d transition metal compounds are expected to replace noble metal electrocatalysts,but transition metal-based catalysts are generally lower in catalytic activity and stability than noble metal-based catalysts.Based on the above problems,the electrolytic water performance of transition metal-based electrocatalysts was effectively enhanced by strategies such as modulation of nanostructures,doping of ions,and construction of composite structures.The main research results are as follows:（1）A series of Fe-Ni₂P（Ni Fe P-MOF）electrocatalysts with multilayer structures were prepared using Ni-MOF as a template by regulating the molar ratio of Ni and Fe through in situ growth and anion exchange,and the morphological structure of the surface of the catalytic material and the electronic structure of the catalytic material was regulated by adjusting the ratio of Fe in Fe-Ni₂P（Ni Fe P-MOF）.The electrocatalytic activity was improved by adjusting the ratio of Fe in Fe-Ni₂P（Ni Fe P-MOF）.The overpotential was only 232 m V and the tafel slope was only 34 m V dec^-1at a current density of 10 m A cm^-2.In addition,good cycling stability was achieved at Ni Fe P-MOF@NF-1.5 electrocatalysts at 10 m A cm^-2 for 12 h（43200 s）.（2）The three-dimensional flower cluster Mo-Ni S@Ni Fe LDH/NF shows excellent OER and HER catalytic activity,cycling durability,and overall water splitting capability in alkaline and neutral environments.Current densities of 10 m A cm^-2 in alkaline and neutral electrolytes require only 184 and 502 m V for OER and 107 and 234 m V for HER,and only 1.54 V and 2.06V for a fully hydrolytic two-electrode system.outstanding catalytic capability but also very good long-term operational stability.It provides a viable technology for the development of low-cost,highly active bifunctional catalysts for energy conversion and storage applications.（3）The three-dimensional porous laminate Ni-Mo-S@Ni Co₂S₄/NF was prepared by secondary hydrothermal-sulfidation,Ni-Mo-S@Ni Co₂S₄/NF shows excellent OER and HER catalytic activity,cycling durability,and overall water splitting catalytic in alkaline to achieve a current density of 10 m A cm^-2 in alkaline electrolytes,only 194 and 187 m V were required for OER and HER,and only 1.61 V was required for overall water splitting to achieve a current density of 10 m A cm^-2.The increase in catalytic activity was mainly due to the encapsulation of Ni-Mo-S nanosheets,which increased the active reaction area,and the doping of heteroatoms,which improved the intrinsic activity of the catalytic material.In addition,the synergistic interaction between Ni-Mo-S and Ni Co₂S₄ interfaces improves the electrocatalytic performance of the catalyst.The porous multistage structure and the high specific surface area further improve the ion diffusion and material transport efficiency,and the electrocatalytic performance is further enhanced.Thus,Ni-Mo-S@Ni Co₂S₄/NF has excellent catalytic ability and long-term stability,which is crucial in practical applications.