Ultrafast Charge Transfer Driven by Strong Adsorption: An Efficient Interfacial Strategy for Photocatalysis.

Abstract

In practical photocatalysis, the strong interaction between surface adsorbates and the cocatalyst is unavoidable, which inevitably triggers a reconfiguration of its electronic structure. However, how this strong adsorption-induced electronic state reconfiguration (SA-ESR) affects the ultrafast charge transfer kinetics remains poorly understood. To fill this gap, we deliberately introduced thiocyanate ions (SCN^-) as a model adsorbate, which selectively adsorb onto the Au nanoparticles deposited on CdZnS, thereby establishing a well-defined strong-adsorption system to probe how such SA-ESR effect governs the ultrafast charge transfer kinetics during photocatalytic H₂ evolution. Comprehensive investigations reveal that the strongly adsorbed SCN^- effectively withdraws electrons from Au, inducing an electronic state reconfiguration to form electron-deficient Au^δ+. Such SA-ESR effect efficiently promotes ultrafast photoelectron transfer from CdZnS to the Au cocatalysts, thereby accelerating the overall charge transfer kinetics and ultimately boosting the photocatalytic H₂-evolution performance. Consequently, the optimized CdZnS/Au-S system (0.05 mM SCN^-, pH = 2) achieves an outstanding H₂-production rate of 8.33 mmol g^-1 h^-1 with visible hydrogen bubble evolution. This work clarifies the deterministic role of strong surface adsorption in driving ultrafast charge kinetics, providing practical insights for the precision design of highly efficient photocatalytic architectures.