Fast response and high contrast of monoclinic MoO₃-based hydrogen gasochromic sensor

In this paper, monoclinic phase MoO₃(β-MoO₃) was successfully prepared by a low-cost, additive-free one-step hydrothermal synthesis method and evaluated for the first time for its performance in hydrogen gasochromic. The research results show that, under room temperature conditions, the monoclinal MoO₃(β-MoO₃) doped with the precious metal Pd exhibits a faster response time and higher contrast in a hydrogen gas environment., with a color change visible to the naked eye occurring in 10 s at 1 % H₂ concentration, from white to blue-black. Compared to Pd/α-MoO₃ it shows superior gas sensing performance. Through the analysis of the relationship between the material's structure and performance, the higher density of Lewis acid sites (Mo⁶⁺) on the surface of β-MoO₃, its lower bandgap energy, and the synergistic effect of its own structure result in a higher content of Mo⁵⁺ formed during the color change process. Therefore, the reaction rate of β-MoO₃-based materials is faster, and the color contrast after coloring is more pronounced. These findings provide an important experimental basis for applying monoclinic MoO₃ as a hydrogen sensing material, demonstrating its potential for future environmental monitoring and safety detection. A new perspective on the field of MoO₃-based high-performance hydrogen gasochromic sensors.