Enhancement of the O2 Sensitivity: ZnO, CuO, and ZnO/CuO Hybrid Additives' Effect on Meso-Tetraphenylporphyrin Dye

Abstract

Semiconductor metal oxide materials have attracted great interest in gas sensors due to their high sensitivity to many target gases. In this study, an oxygen-sensitive optical chemical sensor was prepared in thin-film form by immobilizing meso-tetraphenylporphyrin (H2TPP) in silicon matrix in the presence of ZnO, CuO and ZnO/CuO hybrid nanoparticles as additives. Characterization of synthesized metal oxide powders was performed using XPS, XRD, SEM, and PL spectroscopy. Emission and decay time measurements of H2TPP-based materials were investigated between the concentration range of 0% and 100% [O2] in thin-film forms. The intensity-based signal drops of the additive-free form of porphyrin dye toward oxygen were calculated as 70%. Whereas, the oxygen sensitivities of H2TPP-based sensor slides were measured as 80%, 75%, and 88% in the presence of ZnO, CuO, and ZnO/CuO hybrid particles, respectively. The usage of porphyrin dye with ZnO/CuO hybrid additive provided higher oxygen sensitivity, larger linear response range, higher Stern-Volmer constant (KSV) value and faster response time compared to the undoped form, ZnO and CuO additive-doped forms of H2TPP. The response and the recovery times of the porphyrin-based sensing slide along with ZnO/CuO hybrid particles have been measured as 10 and 20 s. These results make the H2TPP along with the metal oxide additives promising candidates as oxygen probes.