Synergistic enhancement of seawater hydrogen generation via sulfur vacancy enriched and phases engineered CQD loaded CdS photocatalyst

Abstract

The use of photocatalytic water splitting, which involves generation of hydrogen (H₂), is regarded as a possible remedy to counteract the obstacles in the use of fossil fuels and to confront the issues of the energy crisis and environmental contamination. Despite the advancements, there continues to be a scarcity of research on stable and efficient photocatalysts suitable for use in seawater. The present paper describes the process of creating a photocatalyst using a hydrothermal method which combines carbon quantum dots and cadmium sulfide (CdS) nanoparticles. The developed photocatalyst showed excellent photocatalytic H₂ generation (80 450 μmol g⁻¹ in 10 h) and dye degradation efficiency (97% in 60 min). Further, the H₂ generation of bare CdS and CQD@CdS was also tested under seawater conditions where a longer lifetime of particle was observed up to 10 h. A comprehensive analysis was conducted to evaluate the photodegradation mechanism of Rhodamine B dye utilizing the CQD@CdS system. The results showed that the process kinetics can be depicted using a pseudo-second order reaction. The remarkable catalytic activity and outstanding durability of the CQD@CdS can be ascribed to the effective function of the CQDs, which augment the segregation of the photoinduced charge carriers and averts the occurrence of photocorrosion in seawater. Moreover, the CQDs also supported a higher specific surface area and phase transformation in CdS with a dominant hexagonal phase. All these synergistic effects on the properties by the CQD@CdS, aided in creation of a highly efficient photocatalyst that is suitable for applying to solar hydrogen generation.