Exploring Optical and Electrical Gas Detection Based on Zinc-Tetraphenylporphyrin Sensitizer

We developed optical waveguide (OWG), ultraviolet-visible spectrophotometry (UV-vis), and electrically operated gas sensors by utilizing zinc-tetraphenylporphyrin (ZnTPP) as sensitizer. Strikingly, ZnTPP thin-film/K+-exchanged glass optical waveguide (OWG) sensing element exhibits a superior signal-to-noise ratio (SNR) of 109.6 upon 1 ppm NO2 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 (FT-IR) and UV-vis spectra, confirm a strong chemical adsorption of NO2 gas on ZnTPP. Therefore, our studies highlight the selection of suitable detection technique for analyte sensing with ZnTPP.