UV-enhanced NO₂ gas sensors based on In₂O₃/ZnO composite material modified by polypeptides

Abstract

This present study reported a high-performance gas sensor, based on In2O3/ZnO composite material modified by polypeptides, with a high sensibility to NO2, where the In2O3/ZnO composite was prepared by a one-step hydrothermal method. A series of results through material characterization technologies showed the addition of polypeptides can effectively change the morphology and size of In2O3/ZnO crystals, and effectively improve the sensing performance of the gas sensors. Due to the single shape and small size, In2O3/ZnO composite modified by polypeptides increased the active sites on the surface. At the same time, the gas sensing properties of four different ratios of polypeptide-modified In2O3/ZnO gas sensors were tested. It was found that the In2O3/ZnO-10 material showed the highest response, excellent selectivity, and good stability at room temperature under UV light. In addition, the response of the In2O3/ZnO-10 gas sensor showed a strong linear relationship with the NO2 gas concentration. When the NO2 gas concentration was 20 ppm, the response time was as quick as 19s, and the recovery time was 57s. Finally, based on the obtained experimental characterization results and energy band structure analysis, a possible gas sensing mechanism is proposed.

Gd-modified In2O3 for the enhanced xylene sensing

“…In 2 O 3 , a typical n-type semiconductor, has been widely used to detect hazardous gases because of its wide band gap, fast saturation electron migration, and low resistivity [11,12]. When volatile organic compound (VOC) molecules stick to the surface of In 2 O 3 , it not only impacts the electron concentration on the surface of indium oxide, which affects its conductivity, but also alters the electronic state of the surface of indium oxide, which subsequently affects its electrical resistivity properties.…”

Tuning the Surface Electron Accumulation Layer of In2O3 by Adsorption of Molecular Electron Donors and Acceptors

“…[1][2][3] In 2 O 3 doped with Sn, that is, indium tin oxide (ITO), is widely employed as a transparent electrode in (opto)electronic devices, [4] including organic light emitting diodes, [3,5] solar cells, [6,7] field effect transistors, [8] and other devices. [3,[9][10][11] Unintentionally doped In 2 O 3 shows an inherent n-type conductivity, as a surface electron accumulation layer (SEAL) is commonly formed within only a few nanometers at the top surface. [12] This is similar to other transparent oxides, for example, ZnO, [13] Ga 2 O 3 , [14] and SnO 2 , [15] for which the partially filled conduction band can be directly detected by ultraviolet photoemission spectroscopy (UPS).…”