Synthesis and enhanced H2S gas sensing performances of Co-doped NiO@g-C3N4 heterocomposites

Abstract

Metal doping is an efficient approach to improve H2S gas sensing performances, but the metal-doped NiO is still faced poor recovery capability at low working temperature. Herein, Co-doped NiO@g-C3N4 heterocomposites were constructed firstly via a simple solid phase reaction. Texture characterizations indicate that Co-doped NiO@g-C3N4 heterocomposites with the architecture of hierarchical microspheres show high specific surface areas and rich surface oxygen vacancies. The gas-sensitive measurements exhibit that the response value of the heterocomposites with g-C3N4 content of 30 wt% (Co-NiO@g-C3N4-3) increases to 45 toward 20 ppm H2S gas at 172 °C, which is about 1.8 times of Co-NiO (23), as well as response/recovery times decreased to ca. 100/130 s. Besides, excellent repeatability, stability and selectivity of Co-NiO@g-C3N4-3 sensors are obtained. The improved H2S gas sensing performances of Co-NiO@g-C3N4 heterocomposites is mainly contributed to the formation of nano-heterojunctions, which promotes electron accumulation at nano-heterojunctions near Co-NiO, facilitates O2 molecules adsorption on the material surface and accelerates the resistance change of the sensors, resulting the enhanced gas sensing performances.