H2S detection capabilities with fibrous-like La-doped ZnO nanostructures: A comparative study on the combined effects of La-doping and post-annealing

• Published in: Journal of alloys and compounds 2019-08, Vol.797, p.284-301
• Main Authors: Shingange, K., Swart, H.C., Mhlongo, G.H.
• Format: Article
• Language: English
• Subjects: Annealing; Catalysis; Catalytic activity; Comparative studies; Detection; Doping; Gas sensors; Hydrogen sulfide; La-doping; Nanofibers; Nanostructures; Sensors; Zinc oxide; ZnO
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2019.05.060

Herein, we investigated the H2S gas sensing capabilities of ZnO nanofibers (NFs) prepared via the electrospinning method following La-doping and post-annealing treatment at various doping levels and annealing temperatures, respectively. Following a comparative gas sensing study between the pure and La-doped ZnO NFs based sensors upon exposure to H2S at moderate optimal working temperatures, all La-doped ZnO sensors displayed enhanced sensor responses toward H2S as well as fast response/recovery times as compared to that of the pure ZnO based sensor, respectively. Additionally, apart from the fact that these sensors displayed the highest responses, they also revealed relatively high selective responses to H2S. The sensor based on 2 wt% doping annealed at 900 °C displayed the highest H2S response as well as good repeatability, and stability. These findings indicate that the La-doped ZnO NF based sensors could be a promising gas active/sensing layer for detection of H2S in real environments. Combination of various analysis techniques utilized to understand the influence of La-doping and annealing treatment on the H2S sensing performance of the ZnO NFs revealed that synergetic effects of higher surface area, large number of intrinsic defects and the catalytic activity of La are the main reasons for enhanced H2S response with La doping in this work. [Display omitted] •Pure and La-doped nano-fibers were produced via electrospinning approach.•Combined effects of La-doping and annealing on sensing behaviour of ZnO nanofibres.•Enhanced sensing performance towards H2S was achieved with La-addition into ZnO.•Highly La-doped ZnO revealed high selectivity, stability and repeatability to H2S.