Silver Nanoparticles Confined in Nitrogen-Doped Hollow Carbon Sphere for CO<sub>2</sub> Electroreduction: Key Roles of Support Architecture and Poly(Ethylenimine) Precursor

Developing efficient catalysts for the mature application of electrochemical CO2 reduction reaction (CO2RR) to produce value-added chemicals and fuels is crucial. Carbon-supported metals functioning as effective catalysts have attracted extensive attention in the field of CO2RR. However, the understanding of carbon support effects on the electrocatalytic properties is insufficient. Herein, we conduct a comparative study of Ag nanoparticles (NPs) encapsulated in N-doped hollow carbon sphere (Ag@NHCS) and N-doped non-hollow carbon sphere (Ag@NCS) to uncover the structural effects of carbon support in CO2RR. The unique hollow architecture of NHCS with a large surface area and high pore volume guarantees the high exposure of active sites and fast CO2 diffusion. As a result, Ag@NHCS shows improved CO Faradaic efficiency and partial current density compared to Ag@NCS. Furthermore, characterizations and electrochemical results confirmed that poly(ethyleneimine) added as a dispersant agent contributes to the formation of additional active N sites, resulting in an enhanced CO2RR activity. This work provides new insights into the rational design of metal-based carbon catalysts for electrochemical CO2 conversions.