Boosting Photocatalytic Hydrogen Evolution by a Light Coupling and Charge Carrier Confinement Strategy

High-performance photocatalysis requires efficient light absorption and low charge carrier recombination rates. Herein, a light coupling and charge carrier confinement strategy is demonstrated to simultaneously enhance the light absorption efficiency and suppress the charge carrier recombination for high-performance photocatalysis. The strategy is achieved by the delicate incorporation of catalysts into a dual-core-shell structure (e.g., CdS@SiO₂@NaYF₄:Yb/Tm), in which CdS (catalyst), SiO₂, and NaYF₄:Yb/Tm serve as shell, outer core, and inner core, respectively. Interestingly, the absorbed light can be confined within the CdS layer through multiple reflections between the CdS and SiO₂ interfaces, achieving light confinement. This confinement endows a longer light residence time, enhanced light reabsorption and reutilization efficacy, and a higher concentration of photogenerated charge carriers per unit of time. Moreover, the insulating SiO₂ can confine the photogenerated charge carriers within CdS layer, thus shortening their diffusion length for reduced recombination rates. Notably, when employed as the photocatalyst, this dual-core-shell structure showed a superb photocatalytic hydrogen evolution rate up to 74.67 mmol g⁻¹ h⁻¹, which is 11 times higher than that of pristine CdS. This work provides a new strategy for the design and synthesis of high-performance photocatalysts.