Facile Synthesis of Heterogeneous Indium Nanoparticles for Formate Production via CO(2) Electroreduction

In this study, a simple and scalable method to obtain heterogeneous indium nanoparticles and carbon-supported indium nanoparticles under mild conditions is described. Physicochemical characterization by X-ray diffraction (XRD), X-ray photoelectron microscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed heterogeneous morphologies for the In nanoparticles in all cases. Apart from In(0), XPS revealed the presence of oxidized In species on the carbon-supported samples, whereas these species were not observed for the unsupported samples. The best-in-class catalyst (In(50)/C(50)) exhibited a high formate Faradaic efficiency (FE) near the unit (above 97%) at −1.6 V vs. Ag/AgCl, achieving a stable current density around −10 mA·cm(geo)(−2), in a common H-cell. While In(0) sites are the main active sites for the reaction, the presence of oxidized In species could play a role in the improved performance of the supported samples.