The unsaturated coordination and abundant active sites endow amorphous metals with tremendous potential in improving metal oxide semiconductors' gas-sensing properties. However, the amorphous materials maintain the metastable status and easily transfer into the lower-active crystals during the gas-sensing process at high working temperatures, significantly limiting their further applications. Here, a bimetal amorphous PtRu catalyst is developed by accurately regulating the introduction of Pt species into amorphous RuOx supports to realize the highly active and stable H2 S gas-sensing detection. It is found that incorporation of low-concentration Pt species can effectively maintain the amorphous state of initial RuOx and delay the crystallization temperature as high as 100 °C. Further, ex situ XPS and in situ Raman spectroscopy analysis confirm that active Pt species can facilitate H2 S adsorption by strong Pt-S coordination and dissociate the sulfur species to the surrounding support, which contribute to the chemisorption and sensitization of H2 S. Meanwhile, electron transport at the interface between Pt, RuOx and ZnO further activates the reaction process at the surface of the gas-sensitive material. The final PtRu-modified ZnO (PtRu/ZnO) sensor enables the detection of H2 S in the ultra-low concentration range of 15-2000 ppb with remarkable stability.
Keywords: Pt species; Pt-S coordination; bimetal amorphous; micro-electromechanical systems (MEMS) sensors.
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