Evolution of intrinsic 1-3D WO3 nanostructures: Tailoring their phase structure and morphology for robust hydrogen evolution reaction

The use of non-noble electrocatalyst to harness molecular hydrogen by splitting water is highly appreciated. WO3 is one such high-caliber electrocatalyst for Hydrogen evolution reaction (HER) which can be tuned to attain various crystallographic phases and morphologies by altering the surfactants and synthesis parameters of hydrothermal synthesis. Seven different morphologies of WO3 ranging from 1 to 3D nanostructures were synthesized and subjected to HER under extreme pH conditions. The kinetic performance of 1D - nanorods of WO3 outperformed all its counterpart electrocatalysts with an exceptional Tafel slope of 96 and 105 mV dec(-1) at pH = 0 and 14 respectively. The very high aspect ratio of WO3 nanorods in conjunction with an excellent specific surface area by precision tailoring of the crystallographic facets along the (0 0 1) direction enabled better adsorption energies necessary for HER. The nanorod structures of WO3 were further screened by Stainless steel (SS) and Carbon cloth (CC) substrates to determine their efficacy as a real-time electrode for hydrogen production. The nanorods deposited on CC in acidic media displayed an outstanding endurance of 12 h under a static overpotential of -0.5 V vs. RHE and a striking Tafel slope of 76 mV dec(-1) comparable with standard Pt/C. The intrinsic interface of CC compared to SS along with the inherent complexity of WO3 nanorods has enriched the overall kinetic performance required for hydrogen evolution. This research has a promising scope for engineering the morphology and phase structure of WO3 metal oxide at the molecular level for boosting the interfacial active sites required for large scale production of hydrogen.