Hemilabile mechanism for dynamic electronic structure regulation in single-atom catalysts for high-efficiency photocatalytic hydrogen peroxide production.

Owing to their exceptional performance and well-defined structure-activity relationships, single-atom photocatalysts have garnered increasing research interest, particularly in the context of photocatalytic hydrogen peroxide (H2O2) production. However, the reaction mechanisms of the enhanced performance, such as the hemilabile mechanism in heterogeneous catalysis, remain only partially understood. In this work, we successfully loaded Bi single atoms onto S-doped graphene nitride carbon(Bi@g-C3N4-xSx). Synchrotron radiation analysis demonstrated that the reversible breaking and formation of BiS bonds during the reaction promote reactant adsorption and product desorption, respectively, thereby boosting the H2O2 production rate to 450.6 μmol·g-1·h-1. Notably, both high-throughput computational analysis and the Sabatier principle indicate that oxygen (O2) adsorption and H2O2 desorption compete with each other in specific coordination environments. By introducing the hemilabile mechanism, significant dynamic reorganization of the electronic structure at the active site was achieved, enabling the catalyst to circumvent the limitations predicted by conventional volcano plots, which critically depends on the complexity of the coordination environment. The experimental confirmation of the hemilabile mechanism in heterogeneous catalysis offers a new perspective for the rational design of advanced catalysts and lays the groundwork for future innovations in sustainable chemistry and industrial applications.