Implanting Metal-Oxo Single Sites on Metal Surface: A Path to Geometric and Electronic Synergy in Electrocatalysis.

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.