Synthesis And Electrocatalytic Performance Of Single/Double Atom Catalytic Materials

In contrast to the industrial refining of fossil fuels in the modern industrial process,electrocatalytic synthesis can be used in a variety of renewable energy fields to achieve environmental protection.Therefore,electrocatalytic synthesis has been widely concerned by researchers,in which the electric energy used in the electrocatalytic process can be obtained from clean energy.Reduction of carbon dioxide and nitrogen in electrocatalytic reactions has been widely studied in recent years.Single/diatomic catalytic materials have high catalytic activity and clear active center.The electronic structure of the material can be controlled by changing the coordination environment.Therefore,the synthesis of excellent single/diatomic catalysts and the exploration of their surface reaction mechanisms in electrocatalytic processes are the focus of this paper.The main contents are as follows:（1）The electrochemical nitrogen reduction reaction（NRR）provides a bright way to synthesize ammonia.To promote the NRR,the design and synthesis of efficient electrocatalysts with an elucidated reaction mechanism is critically important.Here we demonstrate surface hydrogenation-facilitated NRR to yield NH₃ at low overpotentials on oxygen-deficient In₂O₃ plates decorated with single atom Cd O₅ that have a weak N₂-binding capability.Adsorbed*H is calculated to be first produced via the Volmer reaction（H₂O+e^-→*H+OH^-）and then reacts with dissolved N₂ to generate*N₂H₂.Cd atoms and oxygen vacancies in In₂O₃ jointly enhance the activation of N₂ and accelerate the RDS,boosting the NRR.An NH₃ production rate of as high as 57.5μg h^-1mg_cat^-1 is attained at a mild potential,which is retained to a large extent even after 44 h of continuous polarization.（2）We have developed a simple method to synthesize Mn monatom loaded on N-doped carbon to efficiently catalyze the carbon dioxide reaction to selectively generate CO.Compared with pure NC,the incorporation of Mn single atom can effectively inhibit the side reaction of hydrogen evolution and improve the activity of electrochemical CO₂ reduction（ECR）.At the same time,the performance of ECR can be adjusted by adjusting the content of Mn,the type of N-containing precursor and different calcination temperature.We found that the Mn single atom and its interaction with NC from suitable N-containing precursors are critical to the ECR properties of the prepared materials.In the long-term electrolytic test,Mn SAs/NC shows good stability,and CO Faraday efficiency and ECR current density are almost constant.This work provides an alternative and flexible method for preparing and modulating Mn monatomic catalysts to obtain valuable products from ECR reactions.（3）In electrochemistry,the catalyst plays an irreplaceable role in accelerating the proton-electron transfer in the ECR process.We designed NiM（M:Cd,Pt,Pd）diatomic catalysts to accelerate the transfer of electrons and protons and applied them in ECR reactions.It is proved by electrochemical and theoretical calculation that the introduction of M not only changes the electronic structure of Ni,but also improves the effective collision between CO₂ and Ni.At the same time,*H formed by M cracking water can be quickly transferred to CO₂ activated by Ni atom.As a result of these two improvements,Ni Cd diatomic catalysts produce more than 90%FE_CO in the wide current density range of 200～600 m A cm^-2.This strategy of simultaneously improving the electron proton transfer rate can be applied to various electrochemical reactions.