Ammonia Gas Sensor Using Polypyrrole‐Coated TiO₂/ZnO Nanofibers

Abstract

Highly porous polypyrrole (PPy)-coated TiO 2 /ZnO nanofibrous mat has been successfully synthesized. The core TiO 2 / ZnO nanofibers have an average diameter of ca. 100 nm and the shell of ultrathin PPy layer has a thickness of ca. 7 nm. The NH 3 gas sensor using the as-prepared material exhibited a fast response over a wide dynamic range and high sensitivity with a detection limit of 60 ppb (S/N ¼ 3). Compared to conventional pristine PPy film, the improved performance in NH 3 detection can be attributed to the free access of NH 3 to PPy and a minimized gas diffusion resistance through the ultrathin PPy layer.

TiO2/ZnO and ZnO/TiO2 core/shell nanofibers prepared by electrospinning and atomic layer deposition for photocatalysis and gas sensing

“…Although, in the last decades the gas sensing and photocatalytic properties of both TiO 2 and ZnO nanofibers and thin films have been widely researched [3][4][5][22][23][24][25][26][27][28][29], still there is a lack of knowledge about the gas sensing of core/shell nanocomposites, very thin films with thicknesses of a few nanometers and the influence of exchanging the core and shell materials on the gas sensing and photocatalytic properties. The fabrication of TiO 2 /ZnO composite nanofibers and their gas sensing, photocatalytic activity, bactericidal properties and application in Li-Ion batteries have been reported more often previously [30][31][32][33], while the studies on core/shell composites of TiO 2 and ZnO are still quite limited [34][35][36][37].…”

NO2 Sensing Properties of WO3 Thin Films Deposited by Rf-Magnetron Sputtering

“…Considerable research has been carried out on the development of chemical sensors based on semiconductor metal oxides such as SnO 2 , ZnO, and TiO 2 because of their high sensitivity towards many reducing as well as oxidizing gases [7][8][9]. Tungsten trioxide has attractive electrical properties and reactivity to oxidizing gases making it one of the best candidates for gas sensing applications [10][11][12].…”

Nanostructured TiO2 Layers for Photovoltaic and Gas Sensing Applications

“…TiO 2 can also be used as a porous support for the deposition of an organic sensitive layer as described by Wang et al [50] for the case of ammonia detection with polypyrrole. Polypyrrole (PPy) is a well-known organic semiconductor that was studied for gas detection, in particular NH 3 and VOC.…”

“…This was done for instance with polypyrrole on TiO 2 for NH 3 detection [50] and was studied in our lab for the fabrication of molecularly imprinted polymers (MIP) based on polypyrrole electropolymerized in TiO 2 nanotubes for aldehydes detection.…”

“…To increase this surface-to-volume ratio, Wang et al [50] proposed to synthesize PPy on a very porous TiO 2 /ZnO nanofibre network (diameter of the fibres ~100 nm). The nanofibres were obtained by electrospinning.…”