Chemiresistive H2S gas sensors based on composites of ZnO nanocrystals and foam-like GaN fabricated by photoelectrochemical etching and a sol-gel method

The structure and morphology of gas-sensitive materials were extremely important to performances of gas sensor. In this work, ZnO nano-crystalline (ZnO NCs) was synthesized on foam-like GaN (F-GaN) by sol-gel method as gas-sensitive materials of H2S gas sensor. When ZnO NCs/F-GaN composite structure was used as gas- sensitive materials for detection of H2S with the concentration of 50 ppm at 220 °C. Importantly, rapid response and recovery time was 78 and 31 s, respectively. Enhancement of the sensing response was mainly attributed to the combination between ZnO NCs and F-GaN. In addition, a multiphase catalytic mechanism was proposed to description the catalytic role of F-GaN in the gas sensing procedure. These results further broadened the application of as-prepared metal oxide semiconductor based GaN in the gas sensing field.