Pt-functionalized Amorphous RuO x as Excellent Stability and High-activity Catalysts for Low Temperature MEMS Sensors.

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 RuO x supports to realize the highly active and stable H 2 S gas-sensing detection. It is found that incorporation of low-concentration Pt species can effectively maintain the amorphous state of initial RuO x 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 H 2 S adsorption by strong Pt-S coordination and dissociate the sulfur species to the surrounding support, which contribute to the chemisorption and sensitization of H 2 S. Meanwhile, electron transport at the interface between Pt, RuO x 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 H 2 S in the ultra-low concentration range of 15-2000 ppb with remarkable stability.