Defect-Engineered Pd/WO3-x Nanostructures with Tunable Morphology for Enhanced Visible-NIR Light-Driven Catalysis

Abstract

Semiconductor-based heterogeneous photocatalysis has garnered significant attention, showing considerable promise as a strategy for addressing problems associated with renewable energy and environmental remediation. Plasmonic semiconductors enhance photocatalysis by enabling localized surface plasmon resonance that enhances the light absorption and generates hot carriers. These carriers drive redox reactions efficiently, improving the photocatalytic performance. Herein, Pd nanoparticles (NPs) (2.5 wt%) were successfully deposited onto a non-stoichiometric form of tungsten trioxide (WO3-x) with oxygen defect using a controlled morphology technique. Generating oxygen-deficient states in the WO3 structure significantly enhanced its electronic properties, facilitating improved charge carrier separation and superior catalytic performance. The chemical composition, structural feature, and optical properties of Pd/WO3-x were analyzed using various techniques, including UV-vis spectroscopy, EPR, FT-EXAFS, TEM, XPS, and N2 physisorption analysis. The light-driven catalytic performance of the prepared nanocatalyst was evaluated through the visible-light-induced conversion of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP), utilizing hydrogen generated in situ from ammonia borane (AB). The study demonstrates a crucial role of Pd NPs supported on WO3-x and morphology-controlled photocatalytic activity, particularly when irradiated with visible light compared to dark conditions. Based on scavenger experiments, a plausible reaction mechanism is suggested to explain the enhanced charge separation and photocatalytic performance. Our findings underscore the potential of WO3-x-based materials with plasmonic properties in photocatalytic application reactions.