Inhibition of CdS photocorrosion by Al2O3 shell for highly stable photocatalytic overall water splitting under visible light irradiation

Abstract

Efficiency and stability are the two key points for CdS photocatalyst because its application has been seriously restricted owing to serious photocorrosion issue and the recombination of photo-induced charge pairs. In this paper, CdS nanoparticles (NPs) were surface-modified by chemical inert Al2O3 shell. This modification could prevent nascent formed oxygen induced photo-corrosion and enhance the photo-stability of CdS during water splitting significantly. In addition, it was found that such a shell could enhance efficient separation of photo-induced charge pairs. Besides, with the assistance of artificial gill of removing nascent formed O2 from water, Pt/CdS@Al2O3 photocatalyst can achieve overall water splitting under visible light irradiation. The rate of H2 evolution increased 126 times over Pt/CdS@Al2O3 composite compared with pure CdS NPs, and the stability was maintained in several cycles of reaction without any decrease. The measurement of concentration of Cd2+ in solution after long cycles by ICP method confirmed this anti-photo-corrosion property of Al2O3 shell on CdS. This work provides a new potential way to design and fabricate more stable and efficient CdS-based nanocomposite photocatalysts for versatile solar energy conversion.