Morphology-controlled GaN decoration on SnO2 nanowires for selective H2S gas sensing

초록

In this study, SnO2 nanowires (NWs) were synthesized via a vapor-liquid-solid mechanism at 900 degrees C for 15 min. Depending on the deposition time, GaN was either decorated on the SnO2 NWs or formed a continuous shell around them. The morphologies, structures, and chemical compositions of the synthesized samples were thoughtfully analyzed using various techniques. Detailed microscopic analysis revealed that a deposition time of 1 min led to the formation of GaN nanoparticles (NPs) on the SnO2 NWs, whereas a longer deposition time of 3 min resulted in the generation of a GaN shell over the SnO2 NWs. The H2S gas-sensing characteristics revealed that the pristine SnO2 NW-based sensor had a low response of 1.35-10 ppm H2S gas at 300 degrees C with no selectivity toward H2S gas, whereas the GaN-decorated SnO2 NW-based sensor demonstrated enhanced selectivity. The optimal sensor, in which GaN NPs were decorated on SnO2 NWs, yielded a high response of 33.4 to 1 ppm H2S gas at 300 degrees C. In addition, the optimal sensor was able to detect as low as 50 ppb H2S gas and it exhibited selectivity toward H2S gas, repeatability during seven sequential cycles, and long-term stability after six months. The boosted output was ascribed to the high surface area (23.9 m2/g) resulting from the GaN decoration on the SnO2 NWs and the formation of a sufficient amount of GaN-SnO2 heterojunctions.

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