Electroreduction of CO2 to methanol and formate-species on AgxO@SnO2 and AgxO@Bi2O3 electrocatalysts

The electrochemical conversion of CO₂ into value-added chemicals is a key strategy for the development of sustainable carbon capture and utilization technologies, as well as for renewable fuel production. In this study, Ag_xO@SnO₂ and Ag_xO@Bi₂O₃ nanoparticles were synthesized via a seed-mediated growth method and evaluated as electrocatalysts for the electrochemical CO₂ reduction reaction (CO₂RR). Structural and compositional characterizations were carried out using SEM, TEM, EDS, XRD, and XPS techniques. Revealing the oxidized state of the electrocatalysts (Ag₂O, AgO, SnO₂, and Bi₂O₃). The electrochemical activity and selectivity were assessed in 0.1 M KHCO₃ electrolyte using cyclic voltammetry, Tafel approach, chronoamperometry, and DEMS. Both electrocatalysts exhibited stable activity (−5, and −8 mAcm⁻²) and produced formate-species. However, the electrocatalyst composition had a determinant role in the conversion-selectivity process, Ag_xO@Bi₂O₃ showed enhanced selectivity toward methanol, while Ag_xO@SnO₂ boosted the formation of formaldehyde. The consistent detection of formate-species (formic acid, and formaldehyde) by DEMS in situ of both electrocatalyst suggests a common intermediate pathway, although the distinct electronic and surface properties of the electrocatalysts directed the reaction toward different value-added chemicals.