In-situ Construction And Hydrogen Evolution Performance Study Of Nickel-based Noble Metal Heterostructure

Fossil fuels play an important role in the industrial field,however,the generated byproducts（such as carbon dioxide,nitrogen oxides,etc.）will cause a serious harm to the human health and environment.Hydrogen energy is regarded as a superior alternative to replace the traditional fossil fuels because of its superior energy density,high calorific value,and exceptional conversion efficiency.Among various production protocols,water electrolysis is widely recognized as a highly effective way to generate hydrogen.It is well known that the catalytic performance of most hydrogen evolution catalysts is hardly comparable to platinum（Pt）based catalysts,but the insufficient reserves and expensive price of Pt limit its wide application in the renewable energy field.Therefore,it is very urgent to develop the high performance platinum-like catalysts.Base on many reported works,tuning the electrons coordination between different phases and engineering noble-metal heterostructures on the surface of cheap and easily available nickel-based catalystsare the very effective approaches for designing high-performance electrocatalysts,which are even superior to the platinum catalysts.Therefore,in this thesis,nickel foil and nickel foam are used as substrates to in-situ construct the nickelpalladium bimetallic sulfide and nickel-tungsten-rhodium trimetallic oxide s to form heterogeneous structures between transition metals and noble metals,and explore the effects of different growth parameters on the growth and hydrogen evolution performance of obtained catalysts.The main research contents are listed as follows:（1）Combined with a new pretreatment method,lattice-matched nickel palladium sulfide heterostructures are prepared on the porous nickel foil modified by dielectric barrier discharge plasma.The results show that the electronic redistribution on the phase interface of synthesized Pd₄S-Ni₃S₂/HPNF enhances the adsorption capacity of H^*,causing a high HER performance.Noted that the overpotentials for transferring current densities of j₁₀ and j₅₀₀ are only 44 and 247 m V,respectively.At the same time,the catalyst can maintain a good electrocatalytic stability with j₁₀₀for 50 h.In addition,driven by the current density of j₁₀,the H₂ production of Pd₄S-Ni₃S₂/HPNF is about11.25 mmol/h,which is far higher than most of reported electrocatalysts.Theoretical calculations and in situ Raman spectra indicate that the Pd atoms located at the heterogeneous interface between Pd₄S and Ni₃S₂ weaken the S-H_ads bond,and enhance the reaction kinetics of Volmer and Heyrovsky.（2）Fabric-like nickel-tungsten-rhodium tri-metal oxide heterostructures（Rh₂O₃-Ni WO₄/HPNF）with specific crystal phases wre in situ fabricated with one-step hydrothermal method.The results show that the Rh₂O₃-Ni WO₄/HPNF benefits from the abundant active sites in the heterostructure,and the reduced hydrogen binding energy,as well as improving the charge transfer ability,which cause a high HER activity.Compared with commercial Pt/C（39 m V）stimulated with a current density of j₁₀,the Rh₂O₃-Ni WO₄/HPNF only requires an overpotential of 19 m V.Under an industrial current density of j₁₀₀₀,the overpotentialis only 293 m V.At the same time,Rh₂O₃-Ni WO₄/HPNF maintains a good stability for 100 h under a current density of j₁₀or j₁₀₀.This work provides a new method for engineering two-dimensional rhodium-based materials with a high catalytic performance.