Preparation of highly crystalline NiO meshed nanowalls via ammonia volatilization liquid deposition for H 2 S detection

• Published in: Journal of colloid and interface science 2019-03, Vol.540, p.39
• Main Authors: Yang, Ming, Cheng, Xiaoli, Zhang, Xianfa, Liu, Wei, Huang, Chao, Xu, Yingming, Gao, Shan, Zhao, Hui, Huo, Lihua
• Format: Article
• Language: English
• ISSN: 1095-7103
• DOI: 10.1016/j.jcis.2018.12.106

Novel NiO meshed nanowalls, with characteristics of open geometry, porosity, single crystal and highly crystalline framework, are grown in situ on different substrates (including Al O tube, glass slide, ITO, stainless steel mesh, nickel foam and carbon cloth) via a simple ammonia volatilization liquid deposition process at room temperature and a postcalcination treatment. The calcination temperature can strongly influence the pore size and crystallinity of the product, leading to different gas-sensing performances. The product that obtained at 700 °C (NiO-700) has the advantage in the combination of the largest pore size and high crystallinity, and shows the highest response to H S gas. In 0.01-100 ppm H S gas, the NiO-700 meshed nanowalls based sensor can give evident and reversible response signals at a low optimal operating temperature of 50 °C, the response towards 100 ppm H S can reach to 137.3, the detection limit is as low as 10 ppb. Furthermore, the sensor also exhibits excellent selectivity, repeatability, anti-humidity and long-term stability for H S detection. The results of gas chromatograph-mass spectrometry (GC-MS) and infrared gas analysis (IRGA) reveal that the H S gas can be oxidized to SO after interacting with NiO-700 meshed nanowalls material. Therefore, the possible H S sensing mechanism should be proposed as: H S gas molecules undergo a redox reaction with adsorbed oxygen anion on the surface of NiO-700 meshed nanowalls to form SO ; meanwhile, the electrons restricted by adsorbed oxygen return to the bulk and recombine with the holes, resulting in a decrease in effective carrier concentration of holes and thus generating a change in resistance.