Preparation Of Cu-Ni Bimetallic And Mo-Based Nano Materials And Their Application In Electrocatalytic Nitrate Reduction

Nitrate is considered to be the most common pollutant in groundwater.The massive accumulation of nitrate in water will cause water eutrophication and threaten human health when it enters the human body.At the same time,ammonia（NH₃）is a very important chemical product.Haber-Bosch process is the main method of industrial ammonia production at present,but it has many problems,such as high energy consumption and serious pollution.In contrast,the process of electro catalytic reduction of nitrate to ammonia is more green and environmentally friendly.Therefore,it is of great significance to convert nitrate to recyclable ammonium（NH₄⁺）at room temperature and pressure.Although the process of electrocatalytic nitrate reduction has the advantages of mild conditions and environmental friendliness,it shows the potential for large-scale application.However,there are still many unsolved problems:the competition between the eight electrons transfer pathway and the hydrogen evolution reaction in the reaction process makes the kinetic process slow,the high reaction energy barrier leads to high activity,and the generation of by-products leads to the relatively low Faraday efficiency and selectivity.Therefore,designing and developing efficient catalysts,optimizing the active sites on the catalyst surface,improving the ability of nitrate adsorption and activation,improving the performance of nitrate reduction to ammonia,and inhibiting the generation of by-products are the focus of the current research field,which also provide new ideas for achieving carbon neutrality.The main research contents are as follows:（1）Preparation and properties of catalyst Cu_0.25Ni_0.25:Nano-material Cu_0.25Ni_0.25 was synthesized by solvothermal method by controlling the feed ratio of copper and nickel.Compared with the larger control samples Cu_0.5 and Ni_0.5,Cu_0.25Ni_0.25 has larger electrochemical active area,higher nitrate adsorption equilibrium constant,synergistic effect between bimetals and appropriate d-band center,which optimize the intermediate products and hinder the formation of by-products.Low impedance,activation energy and high apparent rate constant accelerate the reaction kinetics process,which are more conducive to improve the performance of electrocatalytic nitrate reduction for ammonia synthesis.Under-0.3 V,the yield of ammonia is 1.374 mmol h^-1 mg^-1,the Faraday efficiency is as high as 94.5%,and remains above 85%in a wide voltage range.（2）The composite MoO₂/MoS₂ was prepared by solvothermal-calcination.Compared with the catalyst Mo O₂,the synergistic effect and electron transfer of various active components in Mo O₂/MoS₂ improved the catalytic reaction rate.In addition,the catalyst has more active sites because of the larger electrochemical active area,which effectively improves the catalytic activity of the catalyst.The yield of ammonia reached0.81 mmol h^-1 mg^-1 at-0.7 V.The Faraday efficiency reaches 84%at-0.1 V.The influence of p H and nitrate concentration on electrochemical performance was investigated.