Engineering Crystalline Structure of In₂O₃ for Enhanced Electroreduction of CO₂ to Formate

Abstract

The electrocatalytic CO₂ reduction reaction (CO₂RR) to formate provides a sustainable pathway for CO₂ conversion. Indium oxide (In₂O₃)-based catalysts have exceptional selectivity toward formate; however, the regulation and effects of crystalline structure on their performance need to be thoroughly investigated. Herein, we present the methodically controlled synthesis of In₂O₃ catalysts with unique crystallographic structures: rhombohedral In₂O₃ (h-In₂O₃), cubic In₂O₃ (c-In₂O₃), and mixed-phase In₂O₃ (h/c-In₂O₃), and conduct a comprehensive evaluation of their performance in CO₂RR to formate. Remarkably, the h-In₂O₃ catalyst demonstrates a Faradaic efficiency of formate (~95%) and current density surpassing both c-In₂O₃ and h/c-In₂O₃. In addition, the h-In₂O₃ catalyst exhibits excellent comprehensive performance in terms of operating potential range (−0.87 ~ −1.27 V vs. RHE), catalyst stability (70 h), pH range of electrolyte (3.00 ~ 14.00), and CO₂ concentration (20% ~ 100%). Density functional theory studies reveal that among various phases and facets of In₂O₃, the (104) facet of the h-In₂O₃ most effectively stabilizes the critical reaction intermediate, a contribution that is key to its enhanced activity for formate generation from CO₂RR. This investigation elucidates key insights into the engineering crystalline structure of In₂O₃ catalysts pertinent to CO₂RR, thereby presenting a methodical approach for developing highly efficient electrocatalysts.

Keywords

CO₂RR / density functional theory calculations / engineering crystalline structure / formate / In₂O₃

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2026 The Author(s). Carbon Neutralization published by Wenzhou University and John Wiley & Sons Australia, Ltd.