PdAg alloy modified SnO2 nanoparticles for ultrafast detection of hydrogen

Hydrogen is rapidly applied worldwide as a carbon-free energy carrier, while the rapid detection of leaked hydrogen concentration is still a challenging problem. A sensitive material based on PdAg alloy modified SnO2 nanoparticles for rapid detection of hydrogen is successfully prepared. The Pd4Ag/SnO2 based sensor displays ultrafast response rate (1 s @ 1000 ppm), high response value (2843 @ 1000 ppm) and outstanding selectivity to hydrogen. To date, Pd4Ag/SnO2 prepared in this study exhibits the fastest response rate among the bimetal modified semiconductor metal oxide hydrogen sensors reported. Furthermore, PdAg alloy is used to construct a co-sensitizer with low activation energy, further displaying a reduced operating temperature. Detailed sensing mechanism demonstrates that the enhanced hydrogen sensing capability of PdAg/SnO2 is related to the synergistic effect of PdAg alloy, including the catalytic sensitization triggered by Pd and Ag as well as abundant chemisorbed oxygen introduced by PdAg alloy. The PdAg/SnO2 based sensor with superior hydrogen sensing properties provides the possibility for development of a novel rapid response hydrogen sensor.