Electrochemical reduction of CO2 by In doped- SnO2 nanoparticles with high stability and activity toward selective formic acid formation

Abstract

SnO₂ catalysts have been identified as active electrocatalysts for formate (HCOO^─) production in electrochemical CO₂ reduction reactions (eCO₂RR). Nevertheless, it is a tremendous challenge to develop SnO₂ that is durable under the working conditions of eCO₂RR. Here, we present an effective method for the development of indium-doped SnO₂ porous nanoparticles (In (X%) - SnO₂ (NPs)), which are effective electrocatalysts for elevating CO₂ reduction to HCOO^-. We prepared In (X%)-SnO₂ (NPs) with a minimal content of In (≤ 5 %) via the facile evaporation-induced co-assembly (EICA) approach followed by calcination under N₂ and Air atmosphere. Compared with bare SnO₂ (NPs), In(1 %)-SnO₂ (NPs) exhibits a significantly enhanced CO₂ reduction activity with a higher partial current density at −1.2 V vs RHE (-23.56 mA cm⁻²), and higher faradic efficiency (∼98 %) for formic acid production at a wide range of potential (-0.9 to −1.2) V vs RHE. Moreover, the In(1 %)-SnO₂ (NPs) also showed excellent stability for over 50 h and a higher faradic efficiency of 95 % at −0.93 V vs RHE for formate production. It is believed that the porous structure of In(X%)-SnO₂ (NPs) contributes to the enhanced faradic efficiency and stability, and the uniform surface activation of Sn-In/SnO₂ on a homogeneously distributed In(X%)-SnO₂ (NPs) crystal leads to an increase in surface area, oxygen vacancies, electron transfer efficiency, and catalytic activity for eCO₂RR. This approach, which incorporates a porous structure, oxygen vacancies, and element doping, provides an effective route for developing highly active electrocatalysts and enhancing electrocatalytic performance.