Pd on MoO3 nanoplates as small-polaron-resonant eye-readable gasochromic and electrical hydrogen sensor

Hydrogen is a renewable, efficient, and clean energy carrier that can replace petroleum as the future of energy. Eventually, efficient hydrogen detection will become an important requirement for the successful and safe use of hydrogen as a fuel. Among the various hydrogen detection schemes available, gasochromic sensors have major advantages of being intrinsically safe, free of electric contacts in the sensing area, easy to use, and inexpensive. In view of these advantages, we developed an irreversible gasochromic and electrical sensor composed of MoO3 nanoplates and Pd nanoparticles fabricated via green deposition. The amount, distribution, and particle size of the Pd nanoparticles can be controlled easily by modifying the deposition condition, which is necessary for efficient hydrogen sensing. The developed gasochromic sensor was found to change color from white to dark blue upon hydrogen exposure, owing to the polaron-resonance effect; this effect is induced by the coupling of atomic free d-electrons in reduced Mo ion states with H+ ions. Hydrogen concentrations as low as up to 0.1% could be easily detected by the developed sensor. The simple and green fabrication process and detection scheme make the developed sensor highly cost effective and widely applicable in various areas of the hydrogen industry. (C) 2017 Elsevier B.V. All rights reserved.