Tuning CO2 hydrogenation selectivity of Ru catalyst by modifying highly dispersed GaOx species

The selective hydrogenation of CO 2 to either CH 4 or CO is a pivotal reaction for sustainable chemical synthesis, yet controlling product selectivity remains challenging. Although Ru-based catalysts are highly active for CO 2 methanation, their selectivity to CO is typically low. Herein, we demonstrate that gallium oxide (GaO x ) serves as an efficient promoter for Ru/Al 2 O 3 catalysts, switching the dominant product in ambient-pressure CO 2 hydrogenation from ∼98% CH 4 to ∼92% CO. Comprehensive characterization reveals that GaO x engages in a strong electronic metal-support interaction with Ru, which facilitates electron transfer from Ru to Ga, generating electron-deficient Ru sites that weaken CO adsorption. In situ DRIFTS further demonstrates that Ga redirects the reaction pathway from a dual mechanism favoring CH 4 formation on Ru/Al 2 O 3 to a selective route producing CO via formate intermediate decomposition. This work provides fundamental insights into how oxide promoters can steer reaction pathways through electronic effects and offers a rational strategy for designing selective CO 2 hydrogenation catalysts.