Spray deposition of colorimetric H₂ detector with Pd/MoO₃ nanocomposites for rapid hydrogen leakage monitoring at room temperature

Here, we demonstrate a rapidly responsive colorimetric hydrogen detector based on Pd/MoO₃ nanocomposites for hydrogen leakage monitoring at room temperature. The Mo⁵⁺-rich MoO₃ nanobelts are synthesized via a simple one-step hydrothermal method by adding NaCl as the mineralizer. The structure of the detector is fabricated by a general spray deposition technique, not only forming uniform porous microstructures to promote the adsorption and diffusion of H₂ but also solving the issue of performance degradation in ambient conditions by the strategy of on-site fabrication for immediate detection. The detector exhibits a rapid color change which could be recognized with naked eyes within 10 s even in as low as 1% of H₂ at room temperature (25 °C) owing to the high content of active absorption sites (Mo⁵⁺) and the large surface area. The detector is also tested on a hydrogen storage tank with a prefabricated defect in the inner liner and exhibits a prompt and intense color change at the exact hydrogen leakage site, demonstrating its high efficiency in the visual hydrogen leakage detection in complicated systems. The facile fabrication approach as well as the rapid visual detection strategy enable the detector extensively applicable in the hydrogen industry.