ICASEM IV. Uluslararası Uygulamalı Bilimler, Mühendislik ve Matematik Kongresi, Tekirdağ, Turkey, 20 - 23 October 2022, pp.70
In chemical, industrial, medical, biochemical and clinical analysis, the continuous and accurate detection of dissolved and/or gaseous CO2 is very important. In recent studies, 8-hydroxypyrene-1, 3, 6-trisulfonic acid (HPTS) dye, which is a pH sensitive fluorescent indicator with high sensitivity to CO2 gas, is preferred. Researches relating to the improvement of gas sensitivity of HPTS-based optical sensors are very popular. The aim of this study is to enhance the CO2 response of HPTS along with the sol-gel synthesized TiO2 and TiO2@Ag nanoparticles (NPs) as additives. The characterizations of the synthesized metal oxide powders were carried out through XPS, XRD, FT-IR, SEM, and PL spectroscopy. The sensing slides were prepared in the form of a thin film by immobilizing the HPTS dye and TiO2 and TiO2@Ag NPs additives into the ethyl cellulose polymer matrix. Steady state and decay time based spectral responses of the HPTS-based composites were measured as analytical signal in the concentration range of 0–100% [CO2]. Additions of TiO2-based additives to HPTS resulted in many advances such as high relative signal change and larger linear response range, improved sensor dynamics, and higher sensitivity with respect to the additive-free forms. Whereas the CO2 sensitivities were measured as %39, 52% and 70% for undoped form and TiO2 and TiO2@Ag NPs doped forms of the HPTS-based thin films, respectively. The response and the recovery times of the HPTS-based sensing slide along with TiO2@Ag NPs have been measured as 15 and 45 s. These results make the HPTS along with the metal oxide additives promising candidates as CO2 probes.