Boosting H2O2 evolution of CdS via constructing a ternary photocatalyst with earth-abundant halloysite nanotubes and NiS co-catalyst

Abstract

Hydrogen peroxide (H₂O₂), an environmentally friendly chemical with high value, is extensively used in industrial production and daily life. However, the traditional anthraquinone method for H₂O₂ production is associated with a highly energy-consuming and heavily polluting process. Solor-driven photocatalytic evolution of H₂O₂ is a promising, eco-friendly, and energy-efficient strategy that holds great potential to substitute the traditional approach. Here, a ternary photocatalyst, NiS/CdS/Halloysite nanotubes (NiS/CdS/HNTs) is designed and prepared with an earth-abundant clay mineral HNTs as the support and NiS as a co-catalyst. The pivotal roles of HNTs and NiS in the photocatalytic process are elucidated by experiments and theoretical calculations. HNTs serve as the carrier, which allows CdS to be uniformly dispersed onto its surface as small particles, increasing effective contact with H₂O and O₂ for H₂O₂ formation. Simultaneously, it resulted in the formation of a Schottky junction between NiS and CdS, which not only favors photogenerated charges separating efficiently but also provides a unidirectional path to transfer electrons. Consequently, the optimized NiS/CdS/HNTs composite demonstrates an H₂O₂ evolution rate of 380.5 μmol·g⁻¹·h⁻¹ without adding any sacrificial agent or extra O₂, nearly 5.0 times that of pure CdS. This work suggests a feasible idea for designing and developing highly active and low-cost solar energy catalytic composite materials.