Silver single-atom catalyst for efficient electrochemical CO2 reduction synthesized from thermal transformation and surface reconstruction.

Herein, we report an Ag 1 single-atom catalyst (Ag 1 /MnO 2 ), which was synthesized from thermal transformation of Ag nanoparticles (NPs) and surface reconstruction of MnO 2 . The evolution process of Ag NPs to single atoms is firstly revealed by various techniques including in-situ ETEM, in-situ XRD and DFT calculations. The temperature-induced surface reconstruction process from MnO 2 (211) to (310) lattice plane is critical to firmly confine the existed surface of Ag single-atom, i.e. the thermal treatment and surface reconstruction of MnO 2 is the driving force for the formation of single Ag atoms. The as-obtained Ag 1 /MnO 2 achieved 95.7% Faradic efficiency at -0.85 V vs. RHE, and coupled with long-term stability for electrochemical CO 2 reduction reaction (CO 2 RR). DFT calculations indicated single Ag sites possessed high electronic density close to Fermi Level and could act as the only active sites in CO 2 RR. As a result, the Ag 1 /MnO 2 catalyst shows remarkable performance for CO 2 RR, far surpassing the conventional Ag nanosized catalyst (Ag NP /MnO 2 ) and other reported Ag-based catalysts.