Photochemically-Activated p-Type CuGaO₂ Thin Films for Highly-Stable Room-Temperature Gas Sensors

Abstract

The photochemical activation process is a promising way to operate metal oxide gas sensors at room temperature. However, this technique is only used in n-type semiconductors. In this study, we report a highly stable p-type copper gallium oxide (CuGaO2) gas sensor fabricated through the facile sol-gel process. The sensor is capable of detecting O3 gas at room temperature, and its gas response can be further enhanced by ultraviolet (UV) activation. The highest gas response of 7.12 to 5 ppm O3 gas at a UV intensity of 10 mW/cm-2 is achieved at room temperature. In addition, the CuGaO2 sensor shows excellent long-term stability, with a degradation of approximately 3% over 90 days. These results strongly support the solution-processed CuGaO2 as a good candidate for room-temperature gas sensors.

Delafossite CuGaO2-Based Chemiresistive Sensor for Sensitive and Selective Detection of Dimethyl Disulfide

“…The fine scan of Cu 2p core-level spectrum (Figure b) contains two strong peaks at 932.4 (Cu 2p 3/2 ) and 952.2 eV (Cu 2p 1/2 ), confirming Cu + (other than Cu 2+ ) in CuGaO 2 , ,, due to the use of reducing agent ethylene glycol . Ga 2p peaks (centered at 1144.3 and 1117.5 eV) are consistent with previous literature reports . A high ratio (34.7%) of surface oxygen vacancy defects (centered at 531.3 eV) could be found from the O 1s peak (Figure b), which is beneficial for a high sensing activity. ,, By measuring the distance between lattice fringes, an interplanar spacing of 0.224 nm marked in Figure d matches the (104) crystal planes of 3R-delafossite CuGaO 2 , which could also be confirmed by SAED (Figure e) analysis.…”

“…37 A high ratio (34.7%) of surface oxygen vacancy defects (centered at 531.3 eV) could be found from the O 1s peak (Figure 1b), which is beneficial for a high sensing activity. 21,37,39 By measuring the distance between lattice fringes, an interplanar spacing of 0.224 nm marked in Figure 1d matches the (104) crystal planes of 3R-delafossite CuGaO 2 , which could also be confirmed by SAED (Figure 1e) analysis. EDS mapping (Figure 1f−h) clearly demonstrates the presence and homogeneous distribution of all of the anticipated elements.…”

“…38 Ga 2p peaks (centered at 1144.3 and 1117.5 eV) are consistent with previous literature reports. 37 A high ratio (34.7%) of surface oxygen vacancy defects (centered at 531.3 eV) could be found from the O 1s peak (Figure 1b), which is beneficial for a high sensing activity. 21,37,39 By measuring the distance between lattice fringes, an interplanar spacing of 0.224 nm marked in Figure 1d matches the (104) crystal planes of 3R-delafossite CuGaO 2 , which could also be confirmed by SAED (Figure 1e) analysis.…”

“…XPS characterization (Figure 1b) was conducted to investigate the elemental components and chemical state of the surface of the as-prepared CuGaO 2 sample. The fine scan of Cu 2p core-level spectrum (Figure 1b) contains two strong peaks at 932.4 (Cu 2p 3/2 ) and 952.2 eV (Cu 2p 1/2 ), confirming Cu + (other than Cu 2+ ) in CuGaO 2 , 21,29,37 due to the use of reducing agent ethylene glycol. 38 Ga 2p peaks (centered at 1144.3 and 1117.5 eV) are consistent with previous literature reports.…”

Effect of Ultraviolet Light on Mn3O4 Thin Films that are Grown Using SILAR for Room-Temperature Ozone Gas Sensors

“…2 In the last decade, metal oxide semiconductors (MOSs) have been used in gas sensors for detecting O 3 because they are highly sensitive, give a fast response and are stable. [3][4][5][6] There are also various solution-processed methods for synthesizing MOSs so cost is significantly reduced. 7,8 However, a high-quality MOS film with a satisfactory gas response usually requires an additional thermal annealing process.…”