Enhanced chemiresistive sensing performance of well-defined porous CuO-doped ZnO nanobelts toward VOCs

Abstract

Although the post-doping approach as a typical and effective method has been widely employed to improve the gas sensing performance of nanostructured metal oxides, it easily breaks their porous nanostructures. Herein a facile partial cation-exchange strategy combined with thermal oxidation has been developed to prepare porous CuO-doped ZnO nanobelts. Using ZnSe$0.5N 2 H 4 nanobelts as the precursor template, Cu 2 Se-doped precursor nanobelts were obtained with Zn 2+ cations partially exchanged by Cu 2+ cations. After annealing in air, they are further oxidized into well-defined porous CuO-doped ZnO nanobelts. Through manipulating the amount of exchanged Cu 2+ cations, the CuOdoping concentration can be precisely tuned. Based on the assembly approach and in situ thermal oxidation, a uniform and stable sensing film consisting of porous CuO-doped nanobelts was fabricated.Compared with pristine porous ZnO nanobelts, the as-prepared porous CuO-doped nanobelts with ptype CuO|n-type ZnO heterojunctions exhibited better sensing performance toward volatile organic compounds (VOCs). Especially for 3 at% CuO-doped porous ZnO nanobelts, the relative responses toward 100 ppm of ethanol, acetone and formaldehyde were greatly enhanced more than two, four and ten times, respectively. Due to the porous structure, they also displayed a fast response/recovery time.Finally, this enhanced sensing mechanism was discussed for porous CuO-doped ZnO nanobelts.Scheme 1 The process of preparation of porous CuO-doped ZnO nanobelts: (1) Zn 2+ cations of ZnSe$0.5N 2 H 4 nanobelts as a precursor template partially exchanged by Cu 2+ , (2) the transformation from Cu 2 Se doped precursor nanobelts to porous CuO-doped ZnO nanobelts via thermal oxidation.This journal is

ZnO@ZIF-8 Core-Shell Structure Gas Sensors with Excellent Selectivity to H2

“…It is one of the most challenging research directions to improve the selectivity of sensors [19,20]. Common methods to improve the selectivity of MOS gas sensors include doping [21][22][23], microstructure control [24] and surface modification [25]. Qiao et al prepared a sensor with high sensitivity, high selectivity and fast response to H 2 S with a concentration of 20 ppm by doping 0.2% Mo in BiVO 4 [21].…”

“…Common methods to improve the selectivity of MOS gas sensors include doping [21][22][23], microstructure control [24] and surface modification [25]. Qiao et al prepared a sensor with high sensitivity, high selectivity and fast response to H 2 S with a concentration of 20 ppm by doping 0.2% Mo in BiVO 4 [21]. Hiroyuki Abe et al prepared a titanium oxide nanotube thin-film micro-scale gas sensor using a titanium microelectrode local anodization method, and modified the film with platinum nanoparticles to significantly improve its sensitivity to hydrogen and carbon monoxide gas.…”

Advances in Doped ZnO Nanostructures for Gas Sensor

“…Doping in this way could lead to ZnO lattice distortion, which has an impact on the morphology, structure and electrical properties of the ZnO material. Li et al [18] successfully prepared CuO-ZnO nanoribbons by oxygen ion exchanging and thermal oxidation, which could supersede Zn 2 + and precisely control the doping amount of CuO. As shown in Figure. 5(a), the morphology of CuOÀ ZnO composite was unchangeable compared to the ZnO sample.…”

“… (a) SEM images of different amounts of porous 3 at%, CuO‐doped ZnO nanobelts. (b) the relative responses of CZ‐3 porous nanobelts toward all investigated VOCs (100 ppm) in contrast to those of pristine porous ZnO nanobelts at the optimal working temperature of 325 °C [18] …”

“…Wang et al [17] reported that the detection limit of 3DOM Au-ZnO:In for ethanol was as low as 5ppm, which far exceeds the environmental limit of 1000 ppm. Li et al [18] reported that CuO-doped ZnO showed excellent sensing performance to acetone comparing with pure ZnO. Doping could play a key role in affecting the microscopic crystal structure, oxygen vacancy content, and band gap width of the material, which could improve the sensing performance based on the chemical and electronic sensitization sensing mechanisms.…”