Controllable synthesis of hexagonal h-WO₃ microflowers for water oxidation reaction

Tailoring the morphology and crystalline phase of metal oxides induces the variation in structure and surficial microenvironment, in turn influencing their catalytic activity. To date, metastable hexagonal phase WO3 is nearly inactive in electrochemical water oxidation reaction owing to the poor conductivity. Here, we report a facile route to precisely fabricate hexagonal WO3 microflowers with the nanosheet building blocks. In comparison to WO3.0.33H2O microflowers, h-WO3 microflowers could significantly catalyze the transformation of H2O to O2 via water oxidation reaction with high activity of 276 mV at 10 mA/ cm2. The synthesized h-WO3 microflowers exhibit superior oxygen evolution efficiency than WO3.0.33H2O microflowers and commercial IrO2. Coordinative unsaturated W sites and hexagonal channels enable them to greatly activate and dissociate the O-H bond into O2 in alkaline electrolyte. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.