Designing CdS-Based Ternary Heterostructures Consisting of Co-Metal and CoO Cocatalysts for Photocatalytic H Evolution under Visible Light.

Heterostructure formation is an effective method used for designing photocatalysts that solve problems caused by photoexcited charge recombination phenomena associated with the photocatalytic water redox reaction. This work reports a new Co-metal-incorporated ternary heterostructured photocatalyst, CdS/CoO/Co-metal, which enhanced charge separation to increase photocatalytic H evolution 30.5-fold in comparison to pure CdS under visible light. This work demonstrates for the first time the effect of the Co metal on photocatalytic H evolution using the CdS/CoO/Co-metal ternary heterostructure. In the ternary heterostructure, Co metal and CoO act as photogenerated electron- and hole-capturing cocatalysts, respectively. Results from photoelectrochemical studies along with photocatalytic H evolution data proved the enhancement of charge transfer and separation in the CdS/CoO/Co-metal heterostructure due to the addition of Co metal and CoO. Hence, the synergistic charge separation improvement achieved by the combination of CoO and the Co metal with CdS produced a photocatalytic H evolution rate of 9.54 μmol/h, which is the highest reported H evolution rate for a CdS-based system under l sun solar irradiance (>420 nm) to the best of our knowledge.