Strong Electronic Coupling Effects at the Heterojunction Interface of SnO₂ Nanodots and g-C₃N₄ for Enhanced CO₂ Electroreduction

Constructing abundant surface/interface structures has significant impacts on improving the performance of electrochemical CO2 reduction reaction (CO2RR) catalysts. For developing high-performance CO2RR catalysts, herein we report a 0D/2D heterojunction structure of SnO2 nanodots (∼2 nm) confined on graphitic carbon nitride (g-C3N4) nanosheets for promoting the conversion of CO2 to formate. Experimental and theoretical studies demonstrate that the abundant N-coordinating sites of g-C3N4 and highly distributed SnO2 nanodots synergistically lead to strong metal oxide–support interactions, and the substantial heterojunction interface in SnO2/g-C3N4 has induced efficient electron transfer from electron-rich g-C3N4 to SnO2 mainly through p–p orbital couplings. As a result, the SnO2/g-C3N4 heterojunction provides superior activity and stability for the conversion of CO2RR to formate, with a Faradic efficiency of 91.7% at −0.88 V vs RHE. Moreover, the proposed 0D/2D heterojunction strategy was extended to In2O3/g-C3N4, supplying a universal strategy to achieve efficient hybrid catalysts for CO2RR in the production of high-value chemicals.