Synergetic effect of surface plasmon resonance and Schottky junction to drastically boost solar-driven photoelectrochemical hydrogen production and photocatalytic performance of CdS/Al nanorod arrays

Abstract

Photocatalysis is considered as an effective approach to solve the shortages of energy and the pollution problems of environment, because it is a green and sustainable method for utilizing solar energy to produce hydrogen (H2) or to degrade organic contaminants in wastewater. Here, a novel photocatalyst fabricated by decorating CdS nanorod arrays (NRAs) with non-noble metal plasmonic Al nanoparticles (NPs) (CdS/Al NRAs) was designed to substantially boost the solar-driven photoelectrochemical (PEC) H2 evolution and photocatalytic activities. The constructed CdS/Al NRAs demonstrated substantially enhanced PEC H2 evolution and photocatalytic performances. Without external bias, the fabricated CdS/Al NRAs with optimized loading of Al NPs exhibited a substantially enhanced H2 production rate of 90.7 μmol h−1 under simulated solar light irradiation (100 mW cm−2), 3.2 times higher than the pristine CdS NRAs. In addition, the degradation efficiency of Congo red over CdS/Al NRAs reached up to 92.0%, 2.1 times that of the pristine CdS NRAs. The photoluminescence and Mott-Schottky measurements evidently revealed that the hot electron of Al was injected into CdS due to the surface plasmon resonance (SPR) effect. Additionally, the Mott-Schottky tests confirmed the establishment of Schottky barrier in CdS/Al NRAs, prohibiting the injected hot electrons from returning to Al NPs. The experiments evidently demonstrated that the SPR effect and Schottky junction were simultaneously integrated into the constructed CdS/Al NRAs. The synergetic effect of SPR and Schottky junction induced the effective injection of hot electrons and separation of photogenerated charges, leading to substantially enhanced PEC H2 evolution and photocatalytic performances. This work provides a new approach to enhance the PEC H2 evolution and photocatalytic performances of the photocatalyst by using non-noble Al NPs as a plasmonic sensibilizer.