Akademik Veri Yönetim Sistemi
International Journal of Hydrogen Energy, cilt.50, ss.1197-1208, 2024 (SCI-Expanded)
Due to poor selectivity, existing H2 sensors based on pure TiO2 nanostructures do not exhibit good efficiency at low gas concentrations. Therefore, many studies are carried out to improve the gas sensor properties of TiO2s. In this study, the structural and H2 gas sensing parameters of Cu doped TiO2 thin films obtained by using sputtering method were investigated as a function of Cu doping. In the co-sputtering system, direct current (DC) and radio frequency (RF) sources were used to simultaneously deposit of the Ti (fixed at 100 W in DC) and Cu (25, 35 and 45 W in RF). The structural, optical and morphological properties of the films were discussed in the light of XRD, XPS, UV-VIS, SEM and AFM results. XRD results revealed that the produced thin films have anatase TiO2 structure and the crystallite sizes in the most dominant A(110) plane are in the range of 14–18 nm. According to XPS results, copper ratios in Cu25, Cu35 and Cu45 samples were calculated as 0.433%, 1.598% and 2.233%, respectively. It was also found that CuO and Cu2O formations were formed in addition to the anatase phase only in Cu45 sample from these films. It was determined from the 2D and 3D AFM images that the surface roughness values of the films decreased from 63.92 nm to 12.99 nm with increasing Cu doping. In addition to the structural properties of the produced films, hydrogen gas detection performances at 1000 ppm gas concentration and 200 °C temperature were investigated with the current sensitive gas sensing system. The results reveal that Cu doping significantly improves the H2 gas responses and response times of TiO2s. Among the films produced, the highest gas response (2284) and shortest times (τres:128s, τrec:129s) was obtained in Cu45 thin film. This increase in gas responses was explained by the oxygen vacancy model and the results are presented by comparing pristine TiO2 and other 3d transition metal doped TiO2s in the literature.