Optimization of CdS/MoS ₂ Photocatalysts for Phonon‐Enhanced H ₂ Evolution via Indirect Transition Modulation in Layer‐Dependent MoS ₂

Abstract Rational modulation in the transition distribution of electronic band structure is crucial for constructing phonon‐induced enhancement effects for efficient charge separation and thus improving the photocatalytic activity of heterogeneous semiconductor systems. Herein, the indirect/direct transition modulation of layer‐dependent MoS ₂ has been systematically investigated and modeled as a noble metal‐free cocatalyst model to study the spatial behavior of carriers in the presence of the phonon effect by coupling it to the direct semiconductor CdS. Consequently, photocarrier separation at the heterojunction interface is greatly facilitated by the optimized band‐matching mechanism, while phonon‐interfered recombination achieves lifetime extension, which is further elucidated by theoretical simulations. Notably, the water reduction properties of the optimal CdS/MoS ₂ system exhibit a striking apparent quantum efficiency (31.33% at 380 nm), with an H ₂ evolution rate as high as 9.70 mmol h ⁻¹ g ⁻¹ , which is 7.58 times higher than that of pristine CdS. Overall, this work demonstrates the capability of involved phonons for enhancing charge transfer dynamics, and provides great flexibility for precisely designing superior photocatalytic systems by manipulating the electronic band transformation.