Targeted Formation of Bidentate Carbonates at Alkaline Sites for Efficient CO ₂ Photomethanation

Abstract

ABSTRACT Precise design of active sites is crucial for developing highly efficient and selective catalysts. However, in CO 2 conversion, the lack of systematic evaluation of CO 2 promoters and more importantly the atomic‐level understanding of their interactions has limited the continuous progress of CO 2 ‐conversion catalysts. Here, we present a CoAl oxide modified with tailored functional sites and employ CO 2 photomethanation as a model reaction to probe the interactions between reactants and active sites. Specifically, experimental and theoretical results elucidate that the promotion effects of alkaline sites (Li, Na, K, and Cs) originate from their ability to activate CO 2 into effective species of bidentate carbonates (b‐CO 3 *). Meanwhile, the introduced Ru species enable the heterolytic H 2 dissociation and the as‐formed H δ− species, then efficiently drive the successive hydrogenation of b‐CO 3 * intermediates into CH 4 . Based on this targeted activation of CO 2 into b‐CO 3 * (and H 2 into H δ− ), the catalyst delivers an excellent single‐pass CO 2 conversion of ∼77% and CH 4 selectivity of ∼97.7% at a WHSV of 30,000 mL g cat −1 h −1 (2.6 W cm −2 irradiation), with stable operation for nearly 400 h. This work provides valuable insights into targeted activation of CO 2 and offers a new perspective for CO 2 conversion into value‐added chemicals.