Exploring optical and electrical gas detection based on zinc–tetra-phenyl-porphyrin sensitizer

We developed optical waveguide (OWG), ultraviolet–visible spectrophotometry (UV–vis), and electrically operated gas sensors utilizing zinc–tetra-phenyl-porphyrin (ZnTPP) as sensitizer. Strikingly, ZnTPP thin-film/K + -exchanged glass OWG sensing element exhibits a superior signal-to-noise ratio of 109.6 upon 1 ppm NO 2 gas injection, which is 29.5 and 3.8 times larger than that of UV–vis (absorbance at wavelength of 438 nm) and ZnTPP electrical sensing elements prepared on an alumina ceramic tube, respectively. Further results on Fourier infrared spectra and UV–vis spectra, confirm a strong chemical adsorption of NO 2 gas on ZnTPP. Therefore, our studies highlight the selection of suitable detection technique for analyte sensing with ZnTPP. Graphical abstract