Layer-by-Layer Self-Assembly of Metal/Metal Oxide Superstructures: Self-Etching Enables Boosted Photoredox Catalysis

The capability of noble metal nanoparticles (NPs) as efficient charge transfer mediators to stimulate Schottky-junction-triggered charge flow in multifarious photocatalysis has garnered enormous attention in the past decade. Nevertheless, fine-tuning and controllable fabrication of a directional charge transport channel in metal/semiconductor heterostructures via suitable interface engineering is poorly investigated. Here, we report the progressive fabrication of a tailor-made directional charge transfer channel in Pt nanoparticles (NPs)-inlaid WO₃ (Pt-WO₃) nanocomposites via an efficient electrostatic layer-by-layer (LbL) self-assembly integrated with a thermal reduction treatment, by which oppositely charged metal precursor ions and polyelectrolyte building blocks were intimately and alternately assembled on the WO₃ nanorods (NRs) by substantial electrostatic interaction. LbL self-assembly buildup and in situ self-etching-induced structural variation of WO₃ NRs to a microsized superstructure occur simultaneously. We found that such exquisitely crafted Pt-WO₃ nanocomposites exhibit conspicuously enhanced and versatile photoactivities for nonselective mineralizing of organic dye pollution and reduction of heavy metal ions at ambient conditions under both visible and simulated sunlight irradiation, demonstrating a synergistic effect. This is attributed to the imperative contribution of Pt NPs as electron traps to accelerate the directional high-efficiency electron transport from WO₃ to Pt NPs, surpassing the confinement of electron transfer kinetics of WO₃ owing to low conduction level. More intriguingly, photoredox catalysis can also be triggered simultaneously in the same reaction system. The primary in situ produced active species in the photocatalytic reactions were specifically analyzed, and underlying photocatalytic mechanisms were determined. Our work would provide a universal synthesis strategy for constructing various metal-decorated semiconductor nanocomposites for widespread photocatalytic utilizations.