Co and Ni assisted CdS@g-C3N4 nanohybrid: A photocatalytic system for efficient hydrogen evolution reaction

Although the green production of H-2 through water splitting has prompted the search for solar energy harvesting materials, this still remains an ongoing challenge in the field. We report here a novel and cost-effective photocatalytic system, Co and Ni assisted CdS-NRs/g-C3N4 nanohybrid, with the potential to significantly accelerate the solar-assisted water-splitting reaction. In this system, the co-catalysts (Co and Ni) are selectively incorporated as redox mediators to impart electrons and holes away from CdS-NRs/g-C3N4. As a result, an excellent H-2 production rate of 11376 mu mol g(-1)h(-1), turnover number (TON) of 1945 (after 24 h), and external quantum yield (EQY) of 4.4% were obtained at 420 nm and under mild reaction conditions. In addition, when the reaction media was tested in the absence of co-catalysts, a notable decrease in activity was observed indicating the promising role of Ni and Co as cocatalysts. The process of redox shuttle proceeds without adding sacrificial reagents, and relies entirely on the employed cocatalysts to competently separate the oxidation and reduction steps. It is anticipated that this unique cocatalysts-supported nanohybrid can create a synergistic effect between the cocatalysts and the CdS-NRs/g-C3N4 heterojunction, providing more active sites to the catalytic system for the subsequent water splitting redox reaction. The experimental results reveal that the selective and optimum use of dual cocatalysts can be a promising approach to trigger both the production of H-2 and improve the stability of the photocatalytic system for overall water splitting.