Crystallographic Phase and Morphology Dependent Hydrothermal Synthesis of Tungsten Oxide for Robust Hydrogen Evolution Reaction

Abstract Phase and morphology controlled synthesis of nanomaterials have significantly tune the material’s properties. Herein, we demonstrate the concentration of hydrochloric acid, which plays vital role to tune both crystallographic phase, and morphology of tungsten oxide. The high concentration of HCL (50 µL, 37 M) favour in the formation of the monoclinic-WO3 hierarchical flower-like structures composed of nanoplates. On the other hand, hexagonal phase of WO3 nanorods were formed at lower concentration of HCl, respectively. Moreover, hydrogen evolution reaction (HER) was performed and hexagonal-WO3 nanorods was found to be highly active compared to monoclinic-WO3 and comparable with standard Pt/C. The best HER activity of hexagonal-WO3 nanorods was achieved due to its one-dimensional growth, larger surface area, and faster charge transfer. In addition, the electrocatalysts showed a negligible decrease in current density even after 10 h chronoamperometric (i-t) tests, suggesting high stability in acid media.