Heterophase engineering of SnO2/Sn3O4 drives enhanced carbon dioxide electrocatalytic reduction to formic acid

Sn-based electrocatalysts have been gaining increasing attention due to their potential contribution in the conversion of CO2 into HCOOH driven by sustainable energy sources; however, their actual capability to catalyze CO2 reduction reaction (CO2RR) still cannot meet the requirements of commercial-scale applications. Therefore developing Sn-based catalyst is of vital importance. Herein, the sheet-like heterophase SnO2/Sn3O4 with a high density of phase interfaces has been first engineered by a facile hydrothermal process, with Sn3O4 as the dominant phase. The evidences from experiments and theoretical simulation indicate that the charge redistribution and built-in electric field at heterophase interfaces boost CO2 adsorption and HCOO* formation, accelerate the charge transfer between the catalysts and reactants, and ultimately greatly elevate the intrinsic activity of the heterophase SnO2/Sn3O4 towards CO2RR. Meanwhile, the in-situ generated porous structure and metal Sn during CO2 RR improve the mass transmission within the interlayer volume and the conductivity of SnO2/Sn3O4. The heterophase SnO2/Sn3O4 displays high activity and selectivity for CO2RR, achieving an improvement in CO2 reduction current density, 88.3% Faradaic efficiency of HCOOH conversion at −0.9 VRHE, along with a long-term tolerance in CO2RR. This study demonstrates that heterophase interface engineering is an efficient strategy to regulate advanced catalysts for different applications.