Fabrication of mesoporous PdO–TiO2 nanocomposite coated flexible leather for colorimetric hydrogen gas detection at room temperature

Rapid detection of hydrogen gas leakage using flexible colorimetric sensor has been attractive attention in various chemical and automobile industries. However, an existing flexible colorimetric sensor have limitations concerning their lower sensitivity and mechanical strength. In this work, we have fabricated leather-based sensor material via spray coating of mesoporous PdO-TiO₂ nanocomposites (1:1, 2:1, 3:1 for PdO:TiO₂, size: 32–67 nm) on the leather surface and evaluated as a colorimetric hydrogen gas sensor at room temperature (25℃) with relative humidity (RH 10–90%) for the first time. The crystal structure, pore size, surface area, oxidation state, morphology and mechanical strength of prepared sensing materials (PdO-TiO₂ nanocomposite/PdO-TiO₂ leather) were characterized through X-ray diffraction pattern, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett- Teller (BET), Scanning Electron Microscope (SEM) and Universal testing methods. The color difference (ΔE) of sensor materials was quantitatively calculated from CIELAB values and naked eye readout. The obtained results indicated that the sensor material exhibited rapid hydrogen gas detection capabilities by color changing from brown to black (ΔE = 8.71) when exposed to hydrogen gas (4%, H₂). Among the sensor materials, PdO-TiO₂ (2:1) nanocomposite-coated leather can detect 10 ppm hydrogen gas with higher selectivity within 10 s due to the large surface area (59.70–113.19 m²/g) of the mesoporous nanocomposite. The present study will provide a global strategy for fabricating high-performance flexible colorimetric sensor for detecting hydrogen gas in the chemical and automobile industry.