Extraordinary Improvement of Gas-Sensing Performances in SnO₂ Nanofibers Due to Creation of Local p–n Heterojunctions by Loading Reduced Graphene Oxide Nanosheets

Abstract

We propose a novel approach to improve the gas-sensing properties of n-type nanofibers (NFs) that involves creation of local p-n heterojunctions with p-type reduced graphene oxide (RGO) nanosheets (NSs). This work investigates the sensing behaviors of n-SnO2 NFs loaded with p-RGO NSs as a model system. n-SnO2 NFs demonstrated greatly improved gas-sensing performances when loaded with an optimized amount of p-RGO NSs. Loading an optimized amount of RGOs resulted in a 20-fold higher sensor response than that of pristine SnO2 NFs. The sensing mechanism of monolithic SnO2 NFs is based on the joint effects of modulation of the potential barrier at nanograin boundaries and radial modulation of the electron-depletion layer. In addition to the sensing mechanisms described above, enhanced sensing was obtained for p-RGO NS-loaded SnO2 NFs due to creation of local p-n heterojunctions, which not only provided a potential barrier, but also functioned as a local electron absorption reservoir. These mechanisms markedly increased the resistance of SnO2 NFs, and were the origin of intensified resistance modulation during interaction of analyte gases with preadsorbed oxygen species or with the surfaces and grain boundaries of NFs. The approach used in this work can be used to fabricate sensitive gas sensors based on n-type NFs.

Effective Enhancement of Humidity Sensing Characteristics of Novel Thermally Treated MWCNTs/Polyvinylpyrrolidone Film Caused by Interfacial Effect

“…Hence, at low relative humidity, in the thermally treated MWCNTs/PVP film sensor, when a few water molecules were adsorbed by PVP to generate a few H + and H 3 O + , the ions carriers (H + and H 3 O + ) injected into n‐type PVP to neutralize intrinsic electrons of PVP to weaken the barrier of n–p heterojunctions and decrease the resistance of heterojunctions, especially the backward resistance ( R n–p ), which caused that the resistance of sensor apparently decreased. A similar phenomenon of heterojunction has been reported . So the thermally treated MWCNTs/PVP film sensor could work efficiently and exhibit better sensitivity at low RH.…”

Enhanced gas sensing properties to NO2 of SnO2/rGO nanocomposites synthesized by microwave-assisted gas-liquid interfacial method

“…7). Compared to the previous results, the sensor based on the SnO 2 /(0.3%)rGO nanocomposite exhibits the higher response and the fast response and recovery rate ( Table 2) [41][42][43][44][45][46].…”

Significant Enhancement of Hydrogen-Sensing Properties of ZnO Nanofibers through NiO Loading

“…In particular, gas sensors fabricated from one-dimensional (1D) nanostructured metal oxides have become very popular in recent years based on their small size and large surface area, which results in numerous adsorption sites for target gases and facilitates rapid diffusion of gas molecules [3]. Furthermore, 1D nanostructures can be easily synthesized at low cost through simple procedures [4]. Therefore, many researchers have studied the gas sensing characteristics of 1D nanostructured metal oxides [5,6].…”