Amorphous tungsten phosphosulphide-modified CdS nanorods as a highly efficient electron-cocatalyst for enhanced photocatalytic hydrogen production.

Improving the utilization rate of photogenerated electrons generated by visible light excitation is an important factor to improve the activity of photocatalytic decomposition of water for hydrogen evolution. In this study, amorphous tungsten phosphosulphide nanoparticle (WPS NP)-modified CdS (WPS/CdS) catalysts were successfully prepared by a simple physical mixing method. The activity of the 15% WPS/CdS composite catalyst is the best, and the average hydrogen production rate reached 123 257 µmol g-1 in 5 h, and the highest AQE of 9.15% is derived at 420 nm for the 15% WPS/CdS composite catalyst. Simultaneously, five cycle stability tests were performed on the 15% WPS/CdS composite catalyst, and the results show that the 15% WPS/CdS composite catalyst exhibits a high stability. WPS NPs not only improve the visible light absorption rate, but also provide a large number of exposed active sites for the hydrogen evolution reaction. These active sites can capture photogenerated electrons on CdS NRs quickly, and can be used for the hydrogen evolution reaction quickly, promoting the transmission and separation of photogenerated charges and inhibiting the recombination of photogenerated electron and hole pairs. Thus, the utilization rate of photogenerated electrons generated by visible light is improved, and the activity of the photocatalyst is significantly increased.

Photoelectron directional transfer over a g-C3N4/CdS heterojunction modulated with WP for efficient photocatalytic hydrogen evolution.

The separation and transfer of photoelectrons is a crucial factor in the process of photocatalysis. Herein, we successfully designed and prepared WP as a cocatalyst, modified the g-C3N4(CN)/CdS heterojunction structure, achieved the effective separation and directional transfer of photoelectrons, and also efficient photocatalytic hydrogen evolution. In addition, the as-prepared WP-CN/CdS composite photocatalyst not only prominently improved the separation and pre-assigned transfer of photogenerated electrons, but also had abundant surface active sites, which greatly improved the photocatalytic performance of the catalyst; namely, the highest photocatalytic activity of WP-CN/CdS was achieved at 5% WP content and the highest hydrogen production rate could reach 18 238.89 µmol h-1 g-1, which is about 12.49 times that of pure CdS. The detailed characterization studies with SEM, TEM, XRD, XPS, DRS, UV-vis, BET, transient photocurrent, FT-IR etc. effectively supported the abovementioned results, and all the characterization results were in good agreement with each other. Moreover, a possible mechanism of the photocatalytic reaction in the WP-CN/CdS system is proposed.