Introduction: Solar-driven photocatalytic hydrogen production from water splitting is one of the most promising solutions to satisfy the increasing demands of a rapidly developing society. CdS has emerged as a representative semiconductor photocatalyst due to its suitable band gap and band position. However, the poor stability and rapid charge recombination of CdS restrict its application for hydrogen production. The strategy of using a cocatalyst is typically recognized as an effective approach for improving the activity, stability, and selectivity of photocatalysts. In this review, recent developments in CdS cocatalysts for hydrogen production from water splitting under visible-light irradiation are summarized. In particular, the factors affecting the photocatalytic performance and new cocatalyst design, as well as the general classification of cocatalysts, are discussed, which includes a single cocatalyst containing noble-metal cocatalysts, non-noble metals, metal-complex cocatalysts, metal-free cocatalysts, and multi-cocatalysts. Finally, future opportunities and challenges with respect to the optimization and theoretical design of cocatalysts toward the CdS photocatalytic hydrogen evolution are described. Background: Photocatalytic hydrogen evolution from water splitting using photocatalyst semiconductors is one of the most promising solutions to satisfy the increasing demands of a rapidly developing society. CdS has emerged as a representative semiconductor photocatalyst due to its suitable band gap and band position. However, the poor stability and rapid charge recombination of CdS restrict its application for hydrogen production. The strategy of using a cocatalyst is typically recognized as an effective approach for improving the activity, stability, and selectivity of photocatalysts. Methods: This review summarizes the recent developments in CdS cocatalysts for hydrogen production from water splitting under visible-light irradiation. Results: Recent developments in CdS cocatalysts for hydrogen production from water splitting under visible-light irradiation are summarized. The factors affecting the photocatalytic performance and new cocatalyst design, as well as the general classification of cocatalysts, are discussed, which includes a single cocatalyst containing noble-metal cocatalysts, non-noble metals, metal-complex cocatalysts, metal-free cocatalysts, and multi-cocatalysts. Finally, future opportunities and challenges with respect to the optimization and theoretical design of cocatalysts toward the CdS photocatalytic hydrogen evolution are described. Conclusion: The state-of-the-art CdS for producing hydrogen from photocatalytic water splitting under visible light is discussed. The future opportunities and challenges with respect to the optimization and theoretical design of cocatalysts toward the CdS photocatalytic hydrogen evolution are also described.

1 H NMR longitudinal relaxation times (T1,exp of the hydroxyl and methyl group) of methanol in supercritical and subcritical gas-like and liquid-like CO2 + methanol mixtures were obtained as a function of pressure up to 25 MPa and at 293.15 and 308.15 K, respectively. This study was designed to investigate the mechanism of the spin-lattice relaxation (SLR) time T1 in different phase regions of CO2 + methanol as homogenous gas-like, and liquid-like mixtures, and the influence of pressure, temperature, and composition on the relaxation rate was examined. Moreover, the density dependent isotherms of the SLR rates 1/T1,exp were comparatively studied between gas-like and liquid-like binary mixtures. There exists an obvious phase dependent SLR mechanism within the temperature and pressure range carried out herein, that is, the SLR process is dominated by the dipole-dipole (DD) interaction mechanism for both liquid-like mixture and methanol, whereas by the spin-rotation (SR) mechanism for gas-like mixture. Measurement of nuclear magnetic relaxation times can offer micro-dynamic and micro-structural information and are very useful for the study of fluids of strongly