Microwave-Assisted Greener Synthesis of Defect-Rich Tungsten Oxide Nanowires with Enhanced Photocatalytic and Photoelectrochemical Performance

Exploring semiconductor materials with superior photocatalytic activity is desirable to mitigate the crisis associated with rapid depletion of fossil fuels and environmental pollutions. Herein we report the synthesis of orthorhombic stacked WO3 center dot H2O square nanoplates by mixing WCl6 (0.025 M) in ethanol at room temperature via a precipitation method. On the other hand, hierarchical urchin-like W18O49 nanostructures composed of nanowires were synthesized from the preceding solution within 10 min through a microwave-assisted route. The morphology evolution from nanoplates to nanowires proceeds through a dissolution and recrystallization mechanism, as demonstrated in detail by varying the reaction duration and temperature. The as synthesized WO3 center dot H2O nanoplates and W18O49 nanowires were employed for the photocatalytic degradation of rhodamine B and photoelectrocatalytic hydrogen generation through water splitting in a neutral medium. Furthermore, the as-synthesized W18O49 nanostructures are employed as electrocatalysts for hydrogen evolution reaction in both acidic and neutral electrolytes. The enhanced electrocatalytic and photocatalytic activity of W18O49 nanostructures are attributed to their larger surface area, oxygen vacancies, and faster charge transport properties. This work demonstrates a greener and simpler way to synthesize a promising defect-rich material (W18O49) in a short duration and its potential in electrocatalytic and photoelectrocatalytic hydrogen generation, and for degradation of pollutant.