Discoloration Effect and One-Step Synthesis of Hydrogen Tungsten and Molybdenum Bronze (HxMO3) using Liquid Metal at Room Temperature

This paper presents a new route to one-step fabrication and in situ application of hydrogen tungsten and molybdenum bronze (HxMO3) at room temperature and triggers the interdisciplinary research of multifunctional materials between liquid metal and transition-metal oxides (TMOs). Gallium-based liquid metal (GBLM) enables the discoloration effect on TMOs in acid electrolytes at ambient temperature. The underlying mechanism behind this phenomenon can be ascribed to the redox effect at the interface of liquid metal and TMOs in acid electrolytes. Both the theoretical calculations and the experimental results demonstrate that the increasing intercalation of H+ ions into the lattice of WO3 raises the electron density at the Fermi level and charge carriers. H+ ion content in the obtained HxMO3 can be controlled in our approach to meet different requirements. Taking advantage of the one-step fabrication and room-temperature liquid phase nature of the liquid metal, HxMO3 is synthesized under ambient conditions in a very short time, which is inaccessible with conventional solution-processed mechanical alloying, or other methods. The HxMO3 obtained in this one-step approach enables convenient and simple applications for biomimetic camouflage, cost-effective energy storage, H+ ion sensor, and electronic switch.