Abstract
The decoration of noble metal nanoparticles (NPs) on the surface of metal oxide semiconductors to enhance material characteristics and gas-sensing performance has recently attracted increasing attention from researchers worldwide. Here, we have synthesized porous silicon (PS)/WO3 nanorods (NRs) functionalized with Pd NPs to enhance NO2 gas-sensing performance. PS was first prepared using electrochemical methods and worked as a substrate. WO3 NRs were synthesized by thermally oxidizing W film on the PS substrate. Pd NPs were decorated on the surface of WO3 NRs via in-situ reduction of the Pd complex solution by using Pluronic P123 as the reducing agent. The gas-sensing characteristics were tested at different gas concentrations and different temperatures ranging from room temperature to 200 °C. Results revealed that, compared with bare PS/WO3 NRs and Si/WO3 NRs functionalized with Pd NPs, the Pd-decorated PS/WO3 NRs exhibited higher and quicker responses to NO2, with a detection concentration as low as 0.25 ppm and a maximum response at room temperature. The gas-sensing mechanism was also investigated and is discussed in detail. The high surface area to volume ratio of PS and the reaction-absorption mechanism can be explained the enhanced sensing performance.
Highlights
Rapid development of global urbanization and industrialization has caused serious air pollution and endangered the natural environment and human health, detection of hazardous and harmful gases is of great need [1]
Among the various gas-sensitive materials, resistive-type nanostructured metal oxide semiconductors (MOS), such as TiO2, In2 O3, SnO2, ZnO, CuO, and WO3 [4,5,6,7,8,9] have been most attractive in terms ofNO2 detection because of their high sensitivity, simplicity, and low cost [10]
Uniformly distributed pores with an average diameter of 0.93 μm and depth of 6.5 μm can be observed from the plane view and the cross-section view. Such pore sizes are beneficial to the growth of WO3 NRs inside the porous silicon (PS) hole and the easy absorption–desorption of the tested gas
Summary
Rapid development of global urbanization and industrialization has caused serious air pollution and endangered the natural environment and human health, detection of hazardous and harmful gases is of great need [1]. A low cost, highly sensitive, selective, and reliable gas sensor is required to monitor NO2 leakage. There is an urgent demand for developing high-quality gas-sensitive materials . Among the various gas-sensitive materials, resistive-type nanostructured metal oxide semiconductors (MOS), such as TiO2 , In2 O3 , SnO2 , ZnO, CuO, and WO3 [4,5,6,7,8,9] have been most attractive in terms ofNO2 detection because of their high sensitivity, simplicity, and low cost [10]. WO3 , as a typical n-type semiconductor with stable physicochemical properties, is promising for the detection of NO2 in recent years due to its excellent
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