Au/CdS Core-Shell Sensitized Actinomorphic Flower-Like ZnO Nanorods for Enhanced Photocatalytic Water Splitting Performance

Hedgehog Zinc Oxide-Graphene Quantum Dot Heterostructures as Photocatalysts for Visible-Light-Driven Water Splitting

The development of efficient photocatalysts for sustainable hydrogen production via water splitting is vital for advancing renewable energy technologies. In this study, we present the synthesis and characterization of a novel visible-light-active photocatalyst comprising hedgehog-shaped zinc oxide (ZnO) nanostructures coupled with graphene quantum dots (GQDs). Optical properties assessed by UV-visible and photoluminescence (PL) spectroscopy revealed that the ZnO/GQDs heterostructure possessed a reduced band gap (2.86 eV) compared with pristine ZnO (3.10 eV), resulting in improved light absorption and charge separation. Electrochemical analyses indicated a significantly higher photocurrent response and lower charge transfer resistance for the ZnO/GQDs heterostructure compared with the pristine ZnO nanostructure. Photocatalytic tests demonstrated that the ZnO/GQDs heterostructure achieved over 3-fold higher hydrogen (H2) production rates, with an apparent quantum yield (AQY) of 1.51% at 440 nm, and maintained stable activity over prolonged reaction periods. These results highlight the enhanced photocatalytic efficiency and stability of the ZnO/GQDs heterostructure, underscoring its potential as a high-performance photocatalyst for sustainable hydrogen generation. The synergistic effects between ZnO nanostructures and GQDs offer valuable insights into the design of advanced photocatalytic materials for renewable energy applications.

Construction of Ag/Ag2S/CdS Heterostructures through a Facile Two-Step Wet Chemical Process for Efficient Photocatalytic Hydrogen Production

We have demonstrated a two-step wet chemical approach for synthesizing ternary Ag/Ag₂S/CdS heterostructures for efficient photocatalytic hydrogen evolution. The CdS precursor concentrations and reaction temperatures are crucial in determining the efficiency of photocatalytic water splitting under visible light excitation. In addition, the effect of operational parameters (such as the pH value, sacrificial reagents, reusability, water bases, and light sources) on the photocatalytic hydrogen production of Ag/Ag₂S/CdS heterostructures was investigated. As a result, Ag/Ag₂S/CdS heterostructures exhibited a 3.1-fold enhancement in photocatalytic activities compared to bare CdS nanoparticles. Furthermore, the combination of Ag, Ag₂S, and CdS can significantly enhance light absorption and facilitate the separation and transport of photogenerated carriers through the surface plasma resonance (SPR) effect. Furthermore, the Ag/Ag₂S/CdS heterostructures in seawater exhibited a pH value approximately 2.09 times higher than in de-ionized water without an adjusted pH value under visible light excitation. The ternary Ag/Ag₂S/CdS heterostructures provide new potential for designing efficient and stable photocatalysts for photocatalytic hydrogen evolution.