Photocatalytic water splitting is a sustainable technology for the production of clean fuel in terms of hydrogen (H2). In the present study, hydrogen (H2) production efficiency of three promising photocatalysts (titania (TiO2-P25), graphitic carbon nitride (g-C3N4), and cadmium sulfide (CdS)) was evaluated in detail using various sacrificial agents. The effect of most commonly used sacrificial agents in the recent years, such as methanol, ethanol, isopropanol, ethylene glycol, glycerol, lactic acid, glucose, sodium sulfide, sodium sulfite, sodium sulfide/sodium sulfite mixture, and triethanolamine, were evaluated on TiO2-P25, g-C3N4, and CdS. H2 production experiments were carried out under simulated solar light irradiation in an immersion type photo-reactor. All the experiments were performed without any noble metal co-catalyst. Moreover, photolysis experiments were executed to study the H2 generation in the absence of a catalyst. The results were discussed specifically in terms of chemical reactions, pH of the reaction medium, hydroxyl groups, alpha hydrogen, and carbon chain length of sacrificial agents. The results revealed that glucose and glycerol are the most suitable sacrificial agents for an oxide photocatalyst. Triethanolamine is the ideal sacrificial agent for carbon and sulfide photocatalyst. A remarkable amount of H2 was produced from the photolysis of sodium sulfide and sodium sulfide/sodium sulfite mixture without any photocatalyst. The findings of this study would be highly beneficial for the selection of sacrificial agents for a particular photocatalyst.

CdS–SnS2 1D–0D core–shell heteronanostructures were designed for an efficient visible-light photocatalytic H2 evolution reaction.

Fabrication of core–shell heteronanostructures with excellent optical properties and light induced charge separation effects have recently emerged as promising materials for solar to hydrogen conversion. Here, one-dimensional CdS–Au/MoS2 hierarchical core/shell heteronanostructures (CSHNSs) have been successfully synthesized by a facile two-step hydrothermal method. Such heteronanostructures exhibit high efficiency and excellent stability toward hydrogen production. The introduction of Au nanoparticles on to CdS nanorods not only made a Schottky junction with strong plasmonic absorption enhancement but also directed the growth of few layered MoS2 nanosheets as a hierarchical protective shell around the CdS nanorods. These CdS–Au/MoS2 hybrid structures possess a large number of edge sites in the MoS2 layers which are active sites for hydrogen evolution reaction. As a result, the CdS–Au/MoS2 CSHNSs exhibit outstanding hydrogen evolution performance which is 7 times that of pure CdS nanorods. Also these CdS–Au/MoS2 CSHNSs showed greater stability after a long-time test (16 h), and 90% of catalytic activity still remained. The enhanced hydrogen evolution activity of CdS–Au/MoS2 CSHNSs was attributed to the improved visible light absorption and the formation of heterojunctions between CdS, Au, and MoS2 components, which increases the charge separation efficiency and thereby suppresses the electron–hole recombination.