Multi-Hydrogen Adsorption as a Dynamic Electronic Gate for Ultrafast Interfacial Charge Transfer

Reactive materials operate under dynamically evolving adsorption environments, yet how cooperative adsorbates reshape interfacial electronic structure and charge-transfer kinetics remains poorly understood. Here we show that multi-hydrogen adsorption can function as a dynamic electronic gate that reprograms interfacial charge-transfer energetics. Using a sulfur-rich amorphous CoReS_2+x cocatalyst as a model system, we demonstrate that abundant unsaturated sulfur sites enable cooperative multi-hydrogen adsorption, which induces spontaneous electron delocalization and generates an electron-deficient interfacial state. This adsorption-driven electronic redistribution reverses the thermodynamic directionality of electron injection from CdZnS, converting an originally endothermic process into a spontaneous one. Femtosecond transient absorption spectroscopy further reveals that the gated interface accelerates interfacial electron transfer to the ultrafast regime, in agreement with first-principles calculations. The resulting a-CoReS_2+x/CdZnS system achieves highly efficient photocatalytic hydrogen evolution from biomass-derived formic acid with an apparent quantum efficiency of 67.8%. More broadly, these findings establish multi-adsorbate-induced electronic gating as a general mechanism for dynamically programming interfacial charge transfer in catalytic and energy-conversion materials operating under realistic reactive environments.