Selectively triggering photoelectromacro for CO₂to CH₄reduction over SrTiO₃{110} facet with dual-metal sites

In this article, the roles of surface-active sites in dominating photoelectron selectivity for CO₂reduction products are well demonstrated over photocatalyst models of SrTiO₃{100} and {110} facets. On the easily exposed {100} facets terminated with Sr-O atoms, photoelectrons are of 8 mol % for CH₄and 92 mol % for CO generation. The Sr-O-Ti configuration in the {110} facets could enrich the surface charge density due to the lower interface resistance for higher photocatalytic efficiency (1.6 fold). The dual sites of Ti and adjacent Sr atoms are active for strong adsorption and activation of the generated CO* species from primary CO₂reduction on the surface, thus kinetically favoring the activity of photoelectrons (73 mol %) in hydrogenation for CH₂* species and hence CH₄product. Inversely, the poor CH₄selectivity is due to difficulty in the subsequent photoelectron reduction reaction by the weak adsorption of CO* at the single-Sr site on the {100} facets, independent of the electron and proton concentration. Our results may offer some illuminating insights into the design of a highly efficient photocatalyst for selective CO₂reduction.