Selectively triggering photoelectrons for CO2 to CH4 reduction over SrTiO3 {110} facet with dual-metal sites

In this article, the roles of surface-active sites in dominating photoelectron selectivity for CO2 reduction 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 CH4 and 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 CO2 reduction on the surface, thus kinetically favoring the activity of photoelectrons (73 mol %) in hydrogenation for CH2* species and hence CH4 product. Inversely, the poor CH4 selectivity 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 CO2 reduction.

Automated summary

This article demonstrates the crucial role of surface-active sites in governing the selectivity of photoelectrons for CO2 reduction products on SrTiO3 photocatalyst models. The presence of specific configurations on different facets results in varying photoelectron distributions and surface charge densities, affecting the efficiency of photocatalytic reactions. Understanding the impact of surface characteristics on the catalytic process can provide valuable insights for designing highly efficient photocatalysts for selective CO2 reduction.