Menghao Lin, Yang Liu, Tianlei Wang, Yang Din, Jinda Lu, Weiyi Chen
High Resolution Image Download MS PowerPoint Slide Monitoring changes in the dissolved gas compositional within transformer oil, particularly hydrogen (H 2 ), is vital for early fault diagnosis. Among various sensing materials, SnO 2 shows promise for H 2 gas detection but faces challenges, such as high operating temperatures, poor selectivity, and slow response/recovery kinetics. This study successfully synthesizes a series of CeO 2 /SnO 2 composite materials with varying Ce/Sn molar ratios using a hydrothermal method, followed by calcination. The impact of the composite ratio on its microstructure, surface chemistry, and H 2 gas-sensing performance has been systematically explored. The strategic incorporation of CeO 2 significantly boosts the surface oxygen vacancy concentration of SnO 2 . These vacancies serve as active sites, which enhance the adsorption and reactivity of gas molecules. Additionally, the addition of CeO 2 synergistically enhances surface oxygen vacancy concentration (62.27%) and forms a mesoporous structure, which collectively accelerate gas diffusion and electron transfer at the heterojunction interface. The CeO 2 /SnO 2 composite with a 3:7 Ce/Sn molar ratio shows a high response value of 35.69 to 20 ppm H 2 at 175 °C, nearly three times higher than pure SnO 2 . The corresponding response and recovery times are reduced to 116.4 and 168.6 s, respectively. Moreover, the composite also displays excellent linearity ( R 2 = 0.997), long-term stability (>30 days), and selectivity. Energy band analysis reveals a type-II band alignment and work function difference in the CeO 2 /SnO 2 heterojunction, promoting efficient charge transfer at the interface and enhancing electrical conductivity and gas-sensing response. This work provides crucial theoretical insights and material optimization strategies for developing high-performance semiconductor gas sensors and advancing gas-sensing technologies toward H 2 .