Silver Single-Atom Catalyst for Efficient Electrochemical CO Reduction Synthesized from Thermal Transformation and Surface Reconstruction.

We report an Ag single-atom catalyst (Ag /MnO ), which was synthesized from thermal transformation of Ag nanoparticles (NPs) and surface reconstruction of MnO . 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 the MnO (211) to (310) lattice plane is critical to firmly confine the existing surface of Ag single atoms; that is, the thermal treatment and surface reconstruction of MnO is the driving force for the formation of single Ag atoms. The as-obtained Ag /MnO achieved 95.7 % Faradic efficiency at -0.85 V vs. RHE, and coupled with long-term stability for electrochemical CO reduction reaction (CO RR). DFT calculations indicated single Ag sites possessed high electronic density close to Fermi Level and could act exclusively as the active sites in the CO RR. As a result, the Ag /MnO catalyst demonstrated remarkable performance for the CO RR, far surpassing the conventional Ag nanosized catalyst (Ag /MnO ) and other reported Ag-based catalysts.