Ag nanoparticles-decorated α-MoO3 nanorods for remarkable and rapid triethylamine-sensing response boosted by pulse-heating technique

Abstract

Surface interaction between the target vapor and metal oxides can be boosted by noble metal-decorating. The surface effect can contribute to high gas-response but leads to slow recovery rate. In this paper, the Ag nanoparticles (NPs) with sizes about ∼20 nm were uniformly coated onto acidic α-MoO3 nanorods through a wet-chemical reduction method at 50 °C. After sensing assessment for triethylamine (TEA), the optimal sensor based on 2 mol% AgNPs-decorated α-MoO3 nanorods shows the highest response (Ra/Rg = 408.6 to 100 ppm TEA) at 200 °C among the pure α-MoO3 and the other AgNPs/α-MoO3 nanorods. In addition, this sensor depicts a fast response time (3 s) towards 100 ppm TEA, but its recovery time is rather long. The recovery time can be improved (less than 2 min) using pulse-heating strategy at 300 °C in air for 1 min. Moreover, this sensor displays an ultrahigh selectivity towards TEA at the existence of many interfering gases (including NH3, H2S, formaldehyde, ethanol, isopropanol, acetone, and toluene). On basis of the depletion layer model and spillover effect of AgNPs, the enhanced sensing response towards TEA can be illustrated in detail. This work may open an avenue for designing gas sensor with high response and fast detection rate.