Recent Advances in Photo−Activated Chemical Sensors

Abstract

Gas detectors have attracted considerable attention for monitoring harmful gases and air pollution because of industry development and the ongoing interest in human health. On the other hand, conventional high−temperature gas detectors are unsuitable for safely detecting harmful gases at high activation temperatures. Photo−activated gas detectors improve gas sensing performance at room temperature and enable low−power operation. This review presents a timely overview of photo−activated gas detectors that use illuminated light instead of thermal energy. Illuminated light assists in gas detection and is classified as visible or ultraviolet light. The research on photo−activated gas detectors is organized according to the type of gas that can be intensively detected. In addition, a development strategy for advancing photo−activated gas detectors is discussed.

Advanced Field-Effect Sensors

“…The principle of these devices is based on photo-generated charge carriers that interact with the oxygen ions of the gas, resulting in a change in conductivity. The recent progress in photo-activated gas sensors is summarized in a review paper by Lee and Yoo [22]. The photo-activated gas detectors are classified according to the type of target gas and light source in the ultraviolet or visible range.…”

Light-Induced Room-Temperature Gas Sensing by Donor-Doped Anatase TiO2 Ultrasmall Nanoparticles

“…6−10 Photoillumination induces the gas response for MOS and can enhance the sensitivity and shorten the response−recovery time. 11 The light-induced gas response has been reported for different MOSs, such as TaS 2 12 and SnO 2 thin films, 13 ZnO nanowires, 14 TiO 2 , 15 mesoporous WO 3 , 16 and In 2 O 3 /ZnO heterostructure nanoflowers. 9 Recent reports also include the usage of ZnO−Au or MoS 2 /ZnO nanostructures, 17 capable of NO 2 gas sensing 18 not only in dry air but also in N 2 , circumventing the ambient oxygen-induced recovery of the gas sensor materials resistance.…”

“…A comparatively recent alternative is activating the MOS gas sensors with higher photon energy light than the semiconductor band gap . This has been successfully reported for room-temperature detection of oxidative and reductive analyte gases, such as O 2 , CO, NO 2 , H 2 , formaldehyde, and ethanol. − Photoillumination induces the gas response for MOS and can enhance the sensitivity and shorten the response–recovery time . The light-induced gas response has been reported for different MOSs, such as TaS 2 and SnO 2 thin films, ZnO nanowires, TiO 2 , mesoporous WO 3 , and In 2 O 3 /ZnO heterostructure nanoflowers .…”

Insecticide Monitoring in Cattle Dip with an E-Nose System and Room Temperature Screen-Printed ZnO Gas Sensors

“…To improve current e-nose technology, one could also reduce the power usage of the metal oxide gas sensors, as heating them dissipates a lot of energy. More recent studies suggest using UV light as a replacement for heating the metal oxide [32], since UV radiation can also increase the intra-grain conductivity and generate electron hole pairs [33]. This improves gas sensing reactivity at room temperature while significantly reducing the sensor power dissipation.…”

“…This improves gas sensing reactivity at room temperature while significantly reducing the sensor power dissipation. UV illumination allows facile and fast oxidation and reduction [32], allowing such gas sensors to operate at near-room temperatures.…”