Fast responding and highly reversible gasochromic H2 sensor using Pd-decorated amorphous WO3 thin films

Abstract

For the safe use of H2 gas, an eco-friendly energy source in the spotlight but highly explosive at the same time, the need for gas sensors for early H2 detection has been highly increasing. Although promising H2 sensors have been developed with different sensor principles, most of them accompany bulky and large measurement systems which limit their further application to everyday life. In this study, we propose gasochromic H2 sensors based on Pd nanoparticle-decorated amorphous WO3 film (Pd-aWO3) that can visualize H2 detection by the rapid color change of the film with high reversibility using dissociated H+ ions. In specific, extremely fast H+ diffusion coefficient through amorphous WO3 film prepared by electron beam evaporation enables rapid and highly reversible operation that could not be achieved by previously reported crystalline WO3 film. As a result, Pd-aWO3 could exhibit a transmittance change of 57% and super rapid recovery time (16 s), which is the fastest compared to previously reported gasochromic H2 sensors to the best of the authors' knowledge. Moreover, in-situ surface analysis using ambient pressure X-ray photoelectron spectroscopy revealed detailed coloring and beaching mechanisms. This study can provide promising perspectives to future advances in gasochromic H2 sensors toward everyday life application.