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Photocatalytic hydrogen evolution reaction (HER) on semiconductor surface has attracted a great attention in recent years for their abundant applications in solar energy conversion and environmental remediation. Even though a number of materials have been designed for HER, still suffer from little photocatalytic activity which restricts the practical applications. Introducing the vacancies and doping is an effective approach to control the electronic bandstructures of materials which in turn results the improved photocatalytic activity. In this study, we have synthesized one dimensional CdS nanorods by a solvothermal method and then developed a low temperature heating strategy to incorporate the O-doping and S-vacancies simultaneously into CdS towards visible photocatalytic H2 evolution reaction. The heat treated samples with controlled O-doping and S-vacancies offer enhanced visible light absorption and improved photogenerated charge carriers’ separation. Moreover, the S-vacancies also acted as traps to retard the electron-hole recombination rate. As a result, CdS sample treated at 200 °C for 2 hr showed a high photocatalytic H2 evolution activity of 377 μmol/g/h which is 22 times higher than 18 μmol/g/h for pure CdS sample. This work validates a simple thermal treatment method to produce S-vacancies and O-doping for the fabrication of efficient photocatalysts for solar hydrogen production.

Ni100−xFex alloy catalysts are prepared as an alternative to Pt-based catalysts for the hydrogen evolution reaction (HER) in water electrolysis. For optimum bonding and adhesion stability between a carbon paper (CP) electrode and Ni100−xFex alloy particles, the latter (obtained by varying the Ni/Fe ratio) is directly grown onto the CP electrode hydrothermally. The shape, crystallinity, and electrochemical properties of the alloy particles were analyzed using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and linear sweep voltammetry (LSV). Raman spectroscopy identifies that very few crystal defects are generated in the Ni100−xFex alloy catalyst during the HER, resulting in a significant improvement in the alloy's electrocatalytic performance. The XPS alloy catalyst profiles before and after the HER reveal water is easily adsorbed on the Fe2+ component, and more H2 is generated on the Ni0 component. The optimum Ni90Fe10/CP catalyst electrode exhibits an overpotential of − 0.244 V (η = 246 mV) and a Tafel slope of 95.4 mV dec−1 at 100 mA cm−2 in a 1.0 M KOH electrolyte. Moreover, the electrode shows a Faradaic efficiency of 97.07% and excellent catalytic activity over 10 days and after 3000 LSV cycles.

Solar-driven photocatalytic water splitting is an ideal method to produce clean chemical fuels such as H2 and is promising for reducing the usage of fossil fuels and satisfying the increasing worldwide demand for energy supply. Heteronanostructures (HNSs) are useful for designing sustainable, low-cost, and efficient visible-light photocatalysts. In this study, a high-performance novel Nb2O5–SnS2–CdS HNSs was fabricated using Nb2O5 microspheres, SnS2 nanopetals, and CdS nanoparticles via an ultrasonication method and was employed as an efficient solar-light-driven photocatalyst for the production of H2. These Nb2O5–SnS2–CdS HNSs produced via ultrasonication had desirable properties, with a bandgap of ∼1.96 eV, and were photocatalytically active under visible light. The Nb2O5–SnS2–CdS HNSs exhibited excellent stability of H2 evolution rate under natural solar light irradiation: 55887 μmol/g, which was 2.19 and 2.79 times greater than those for Nb2O5–CdS and SnS2–CdS HNSs, respectively. The enhanced photocatalytic activity of the Nb2O5–SnS2–CdS heterostructure was attributed to the enhanced visible absorption and improved charge separation, which prevented the recombination of electron–hole pairs during the photocatalytic reactions. The present study indicates the vital role of the interactions in the HNS metal sulfides and oxide for improving charge-carrier separation, which is significant for the development of highly efficient Nb2O5–SnS2–CdS HNS photocatalysts for H2 evolution.