Controllable band structure of ZnO/g-C3N4 aggregation to enhance gas sensing for the dimethylamine detection

Volatile organoamines exist widely in various industrial and commercial products. The chronic and prolonged exposure to amines can compromise human health and cause even the risk of serious illness. Herein, the aggregation of ZnO decorated with g-C3N4 (ZOCN) is synthesized and it can serve as enhanced sensitive sensor for the detection of dimethylamine (DMA). The structure, morphology, composition and band structure of the materials are characterized by various analytical techniques. The results show that, controllable additions of g-C3N4 affect self-assemble of nanoparticles and aggregation structure, even energy band, as confirmed by DFT calculation. Notably, the formed heterojunction is conductive to electron transfer and adsorption of more O2 molecules to form reactive oxygen species, thereby promoting the reaction between oxygen and DMA and leading to high sensitivity to DMA with a detection limit of 920 ppb and about 2.5 times higher sensitivity than pristine ZnO. ZOCN-based sensor shows a high selectivity to DMA, a fast response time (1 s) and a fast recovery time (40 s) to various concentrations of gas phase DMA at low temperatures. Additionally, the sensor exhibits a linear relationship between the response and concentration of DMA vapor in a wide concentration range, a characteristic that is desirable for quantitative analysis in gas sensors.