Synchronizing the directional photogenerated transfer of electrons and regulating the CO 2 photocatalytic reduction process are key to achieving the efficient and highly selective photocatalytic reduction of CO 2 . The design of highly-dispersed active sites and the efficient collaboration of multiple sites are of great importance in attaining the above target. Herein, a reverse etching route was first proposed to confine Bi single atoms and nanoparticles as dual-sites for assisting CO 2 photoreduction on TiO 2 , avoiding the mutual masking of the active sites. The Synergism of the dual-sites achieves the hydrodeoxygenation of * COOH and ushers the directional conversion of CO 2 to CH 4 . Highly dispersed single Bi atoms could induce the transfer of photogenerated electrons, enhance CO 2 absorption, and further provide active sites for reducing CO 2 to *COOH intermediates. Besides, appropriate Bi nanoparticles could promote the separation and transfer of photogenerated and inhibit the formation of hydroxyl groups; more importantly, they could promote the release of protons, which would further accelerate the conversion of *COOH to CH 4 . After being integrated, the optimized dual-Bi/TiO 2 catalyst achieves a CH 4 generation rate of 103.89 μmol·g −1 ·h −1 with an impressive selectivity of 96.87 % as well as remarkable durability for photocatalytic CO 2 reduction. This work provides new insights into developing robust catalysts through the artful design of synergistic catalytic sites for efficient photocatalytic CO 2 conversion.
Promising and diverse strategies have emerged for creating isolated catalytic active sites, such as single-atom catalysts and single-atom alloys, aiming at achieving efficient and selective catalysis. However, the structural tunability of isolated active sites has largely been restricted to their chemical compositions, primarily due to the absence of a higher-order structure associated with these isolated atoms. To address this, an additional degree of freedom is introduced by incorporating functional groups onto these active sites. Specifically, metal-oxo single sites are implanted onto metal surfaces to achieve geometric and electronic synergy. As a demonstration of this concept, bismuth single sites are embedded onto a palladium surface, promoting p-d orbital hybridization and facilitating the formation of terminal Bi-oxo species. This cooperative interaction optimizes the adsorption strength of intermediates through both covalent electronic hybridization and geometric interactions. The Bi-oxo-embedded Pd hybrid nanostructure, created through consecutive etching and displacement deposition, enables the simultaneous optimization of key intermediates for the electrocatalytic oxygen reduction reaction. Remarkably, this hybrid nanostructure achieves specific and mass activities 11.03 and 8.45 times greater than those of commercial Pt/C, respectively. Furthermore, it demonstrates high stability and achieves a power density of 280 mW cm −2 in direct methanol fuel cells.
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