Enhanced electrocatalytic CO₂ reduction to formic acid using nanocomposites of In₂O₃@C with graphene

In₂O₃ is an effective electrocatalyst to convert CO₂ to formic acid (HCOOH), but its inherent poor electrical conductivity limits the efficient charge transfer during the reaction. Additionally, the tendency of In₂O₃ particles to agglomerate during synthesis further limits the exposure of active sites. Here we address these issues by leveraging the template effect of graphene oxide and employing InBDC as a self-sacrificing template for the pyrolysis synthesis of In₂O₃@C. The resulting In₂O₃@C/rGO-600 material features In₂O₃@C nanocubes uniformly anchored on a support of reduced graphene oxide (rGO), significantly enhancing the active sites exposure. The conductive rGO network facilitates charge transfer during electrocatalysis, and the presence of oxygen vacancies generated during pyrolysis, combined with the strong electron-donating ability of rGO, enhances the adsorption and activation of CO₂. In performance evaluation, In₂O₃@C/rGO-600 exhibits a remarkable HCOOH Faradaic efficiency exceeding 94.0% over a broad potential window of −0.7 to −1.0 V (vs. reversible hydrogen electrode (RHE)), with the highest value of 97.9% at −0.9 V (vs. RHE) in a H-cell. Moreover, the material demonstrates an excellent cathodic energy efficiency of 71.6% at −0.7 V (vs. RHE). The study underscores the efficacy of uniformly anchoring metal oxide nanoparticles onto rGO for enhancing the electrocatalytic CO₂ reduction performance of materials.