Improving the efficiency of gasochromic response by using a dual sample system with WO₃ thin films with Pd and Pt catalysts

Hydrogen, when produced using renewable energy sources, is a zero-emission fuel that does not emit harmful pollutants. Therefore, it is increasingly being researched as an alternative to traditional fossil fuels, although it poses certain risks due to its explosive nature. Gasochromic materials such as tungsten oxide (WO₃) thin films show promise for passive and remote hydrogen sensing. In this work the gasochromic reaction of WO₃ thin films with palladium and platinum catalysts, deposited by electron beam evaporation, was investigated using various sample configurations during measurements. Gasochromic measurements revealed that Pd-coated WO₃ thin films exhibited superior sensor response and faster response and recovery times compared to Pt-coated films, which demonstrated better long-term stability. The aim of this study was to investigate gasochromic properties of a novel configuration consisting of two samples simultaneously mounted on a holder, which enabled a multiplied gasochromic response compared to that of a single sample. Furthermore, this is the first time such an approach has been reported for WO₃-based systems exhibiting gasochromic properties. Additional experiments confirmed the high selectivity of the sensor toward hydrogen and its excellent long-term stability even after one year. Moreover, in-situ X-ray Diffraction measurements were performed to gain insight into the structural changes occurring during the gasochromic reaction. A universal configuration offering a simple and effective way to significantly enhance gasochromic response was also proposed.