Large-Scale Tunable 3D Self-Supporting WO₃ Micro-Nano Architectures as Direct Photoanodes for Efficient Photoelectrochemical Water Splitting

Hydrogen production from water based on photoelectrochemical (PEC) reactions is feasible to solve the urgent energy crisis. Herein, hierarchical 3D self-supporting WO 3 micro-nano architectures in situ grown on W plates are successfully fabricated via ultrafast laser processing hybrid with thermal oxidation. Owing to the large surface area and efficient interface charge transfer, the W plate with hierarchical porous WO 3 nanoparticle aggregates has been directly employed as the photoanode for excellent PEC performance, which exhibits a high photocurrent density of 1.2 mA cm –2 at 1.0 V vs Ag/AgCl (1.23 V vs RHE) under AM 1.5 G illumination and reveals excellent structural stability during long-term PEC water splitting reactions. The nanoscale and microscale features can be facilely tuned by controlling the laser processing parameters and the thermal oxidation conditions to achieve improved PEC activity. The presented hybrid method is simple, cost-effective, and controllable for large-scale fabrication, which should provide a new and general route that how the properties of conventional metal oxides can be improved via hierarchical 3D micro-nano configurations.