S-Scheme Heterostructured CdS/g-C₃N₄ Nanocatalysts for Piezo-Photocatalytic Synthesis of H₂O₂

Abstract

Sustainability in catalysis is increasingly becoming the primary target in academic and industrial studies. Regarding the material perspective, designing heterojunction nanocatalysts to produce small molecules, such as hydrogen peroxide (H 2 O 2 ), has been an attractive research theme in recent decades. Nonetheless, most reported materials suffer from a complicated synthetic process with various steps and using unbenign solvents, hindering practical applications on an industrial scale. This study proposed a facile one-step way to fabricate heterostructured CdS/g-C 3 N 4 nanocatalysts to produce H 2 O 2 from water and oxygen under light and ultrasound irradiation. The results showed that the formation of H 2 O 2 mainly relies on oxygen radical species. Oxygen is initially converted into superoxide via excited electrons from CdS, followed by the formation of singlet oxygen from the oxidation process in g-C 3 N 4 sites. Interestingly, the formation of H 2 O 2 in an inert atmosphere is associated with the in situ evolution of oxygen from water oxidation due to the suitable electronic band position of g-C 3 N 4 to drive multioxidation reactions. Charge transfer characterizations illustrate the S-scheme mechanism in the catalytic process, giving a better understanding of the charge transportation phenomenon, thus providing a critical pathway in designing and developing heterojunction materials for catalysis with easier catalyst preparation and operation processes.