Recent Advances in Photo-Activated Chemical Sensors

The computational density functional theory (DFT) investigating the CO gas adsorption on magnesium porphyrin nanorings (Mg4@PNR4)

The decorated butadiyne-linked four porphyrin nanorings with four magnesium cations (Mg4@PNR4) represented a novel class of nanoscale molecules. This Mg4@PNR4 system could be considered as a high surface area with favorable chemical and physical properties which has inherent ability to form hydrogen and covalent bonds. The Mg4@PNR4 system could contribute to air purification and greenhouse gas decrease by efficiently capturing toxic gases such as carbon dioxide and nitrogen oxides. This study aims to scrutinise and improve the CO gas sensing capacity of the Mg4@PNR4 system with four porphyrin rings using density functional theory (DFT). In all configurations, the adsorption values were negative which indicates adsorption process is physical and reversible. Also, the CO gas adsorption, in all configurations, increased the band gap of nanoring by 114-121 % and reduced the conductivity of the nanoring. Additionally, the recovery times were in the range of nano, pico and femto seconds which showed the rapid desorption of CO gas after physical adsorption. According to the NBO investigations, the amount of positive charge in the magnesium ions decreases and the positive charge in the gas increases during the adsorption of CO molecule on the nanoring. Eventually, the FMO analysis and the electron transfer amount (ΔN) showed that the electrons were transferring from CO to the porphyrin nanoring.

Light-activated semiconductor gas sensors: pathways to improve sensitivity and reduce energy consumption

Resistive type gas sensors based on wide-bandgap semiconductor oxides are remaining one of the principal players in environmental air monitoring. The rapid development of technology and the desire to miniaturize electronics require the creation of devices with minimal energy consumption. A promising solution may be the use of photoactivation, which can initiate/accelerate physico-chemical processes at the solid-gas interface and realize detection of flammable and explosive gases at close to room temperature. This work examines the mechanism underlying the increased sensitivity to various gases under photoactivation. The review is intended to clarify the current situation in the field of light-activated gas sensors and set the vector for their further development in order to integrate with the latest technological projects.

Advanced Field-Effect Sensors

Sensors based on the field-effect principle have been used for more than fifty years in a variety of applications ranging from bio-chemical sensing to radiation detection or environmental parameter monitoring [...].