Low-temperature Plasma-assisted Preparation Of Nickel Foam-based Nanomaterial Catalysts And Their Electrocatalytic Performance

With the consumption of fossil fuels and environmental pollution becoming more and more serious,hydrogen energy has attracted more and more attention as a pollution-free and renewable clean energy.At present,hydrogen production by electrolysis of water is one of the important ways to produce hydrogen on a large scale.The key to achieving large-scale production of electrolyzed water lies in the development of electrocatalysts with high activity,high stability and low price.The small reserves and high prices of precious metal-based catalytic materials restrict their commercial applications.Therefore,it is particularly important to develop a catalyst with stronger activity,lower cost and better stability to replace precious metal catalysts.Nickel foam(NF),as a three-dimensional porous metal material,is widely used in the fields of nickel-hydrogen batteries and fuel cells,and has great application prospects in the field of hydrogen production by electrolysis of water.In view of the above problems,this paper proposes a solution based on low-temperature plasma,using plasma technology to modify/prepare the electrolysis water catalyst based on NF,and study the electrochemical performance of the obtained catalyst material.This thesis aims to improve the electrocatalytic performance of oxygen/hydrogen evolution reaction(OER/HER),relying on low-temperature plasma technology,to micro-design and control the structure of the catalyst to build more oxygen vacancies and expose more electrochemically active sites.The main research content and the obtained results of this paper are as follows:(1)We modified the nickel foam by high-purity oxygen jet plasma,and prepared an ultra-thin non-stoichiometric nickel oxide layer with mixed Ni³⁺/Ni²⁺ions and oxygen-rich defects on the surface of the foamed nickel in an ultra-fast manner.At the same time,light emission spectroscopy was used to find that the plasma produced a variety of reactive oxygen species,including oxygen atoms(O)and hydroxyl radicals(OH·),as well as O₂⁺and e.These substances have high activity.When the surface of the nickel foam is bombarded by these high-energy active particles,it can quickly react with metal Ni atoms,thereby forming an ultra-thin Ni_xO_y layer on the surface of the NF.(2)In order to improve the HER performance of the nickel foam-based catalyst,we use the NF as the substrate to synthesize the precursor Ni Mo O/NF by the hydrothermal method and the air annealing process,and then the precursor is assisted by phosphating by plasma enhanced chemical vapor deposition(PECVD),P-Ni Mo P/NF catalyst was prepared.The experimental results show that the prepared P-Ni Mo P/NF catalyst has excellent electrocatalytic performance for hydrogen evolution reaction.Only 3 and 98m V overpotentials are required to derive the current densities of 10 and 100 m A cm^-2 in1 M KOH,respectively.Not only that,at a high current density exceeding 100 m A cm^-2,the HER performance even exceeds the commercial 40%Pt/C catalyst.The excellent performance of the catalyst is attributed to the synergy between the formation of many oxygen vacancies and the bimetallic phosphide with the participation of plasma.