Nanoconfined Tin Oxide within N-Doped Nanocarbon Supported on Electrochemically Exfoliated Graphene for Efficient Electroreduction of CO to Formate and C1 Products.

Developing low-cost and effective electrocatalysts for electrochemical reduction of CO (COER) is critical to CO conversion and utilization. Herein, we report a novel two-dimensional (2D) confined electrocatalyst composed of core-shell structured tin oxide nanoparticles (NPs) encapsulated into N-doped carbon (NC) supported on electrochemically exfoliated graphene (SnO⊃NC@EEG) prepared by carbonization of a 2-methylimidazole/SnO complex@poly(vinyl pyrrolidone) (PVP)-modified EEG precursor. The SnO NPs with an average size of ∼10 nm are confined in the NC shells with a thickness of 0.7 nm derived from 2-methylimidazole. The resulting 2D confined electrocatalyst significantly enhances the COER performance with a small onset potential of -0.45 V, and high Faradic efficiencies of 81.2 and 93.2% for HCOO and C1 products at -1.2 V, respectively, which is far superior to other reported SnO/carbon-based COER hybrids. The superb COER catalytic activity of the SnO⊃NC@EEG has resulted from the positive effect of N dopants and a strong confinement effect, which significantly expedites the CO adsorption associated with charge transfer from the NC to SnO NPs during COER electrocatalysis.