Zn Single-atom Catalyst: Preparation And Its Application In CO₂ Electroreduction

From the birth of the industrial revolution on,the rapid consumption of fossil fuels has caused a large amount of CO₂ gas emissions,which has led to a serious greenhouse effect.In such severe situations,transformation of CO₂ to energy resource has become an effective solution.Thus,electrochemical reduction of CO₂ to CH₄ is one of the promising methods.Based on this,we designed and synthesized a catalyst with single-atom Zn supported on microporous N-doped carbon substrate（SA-Zn/MNC）.Spherical aberration electron microscope characterization and synchrotron radiation analysis demonstrate that the Zn is atomically dispersed and the coordination structure is Zn-N4,which is the active site of the catalyst.At-1.1 V vs.RHE,the reduction current density and Faraday efficiency in 1.0 M KHCO₃ solution are-39.9 m A cm^-2 and85%,respectively.After 35 hours of continuous electrolysis,the current density and the Faraday efficiency did not significantly decrease,which shows good electrocatalytic stability.Theoretical calculations show that Zn single atom hinders the production of CO and promotes the production of*OCHO intermediate,which is beneficial to the generation of methane.This work may inspire new exploration and design of stably efficient single-atom catalysts for electrocatalytic CO₂ reduction.According to the preparation conditions of the SA-Zn/MNC single-atom catalyst,we have extended its preparation method.For the synthesis,hydroxylamine hydrochloride was used as the nitrogen source,glucose was used as the carbon source,and metal salts were employed as the metal sources of the single-atom precursors.A series of high-loading single-atom catalysts were prepared by calcination in argon atmosphere including Pb,Pt,Hf,W,and Pd.Electron microscopy,XRD,XPS,and synchrotron radiation characterization proved their successful preparation.The method is a cost-effective,simple and general strategy for synthesis of single-atom catalysts.