Enhanced Ethanol Sensing Characteristics of In₂O₃-Decorated NiO Hollow Nanostructures via Modulation of Hole Accumulation Layers

Abstract

In this work, we report a dramatic enhancement in ethanol sensing characteristics of NiO hollow nanostructures via decoration with In2O3 nanoclusters. The pure NiO and 1.64-4.41 atom % In-doped NiO and In2O3-decorated NiO hollow spheres were prepared by ultrasonic spray pyrolysis, and their gas sensing characteristics were investigated. The response (the ratio between the resistance in gas and air) of the In2O3-decorated NiO hollow spheres to 5 ppm ethanol (C2H5OH) was 9.76 at 350 °C, which represents a significant improvement over the In-doped NiO and pure NiO hollow spheres (3.37 and 2.18, respectively). Furthermore, the 90% recovery time was drastically reduced from 1880 to 23 s, and a selective detection of ethanol with negligible cross-response to other gases was achieved. The enhanced gas response and fast recovery kinetics were explained in relation to the thinning of the near-surface hole accumulation layer of p-type NiO underneath n-type In2O3, the change of charge carrier concentration, and the variation of oxygen adsorption.

Enhanced sensitive and selective xylene sensors using W-doped NiO nanotubes

“…When the sensors based on p-type semiconductor are exposed to air, the adsorption of oxygen with a negative charge on the surface of semiconductors is a known to form a hole accumulation layers (HAL) near the particle surfaces through electrostatic interaction between oppositely charged species (negatively charged oxygen and positively charged holes), and resulting in the decrease of resistance. When the sensors based on p-type semiconductors is exposed to a reducing gas, the gas will be oxidized by the negatively charged ionized oxygen [25,33]. At the same time, the release of electrons by the reaction between reducing gases and ionized oxygen at the surface will decrease the charge carrier concentration near the surface by electronhole recombination, which will increase the resistance of sensor.…”

“…As already reported, the gas sensing properties of NiO nanomaterials could be enhanced by doping or composite with other metal oxides. For example, Kim et al [33] have been synthesized NiO hollow spheres decorating with In 2 O 3 by ultrasonic spray method, which dramatic enhanced the ethanol sensing characteristics. Yoon et al [34] have been demonstrated that the response to ethanol could be improved via doping NiO nanofibers with Fe 3+ .…”

Synergetically Selective Toluene Sensing in Hematite‐Decorated Nickel Oxide Nanocorals

“…The effective surface decoration maximized p – n junctions between NiO and α‐Fe 2 O 3 . Well‐distributed nanoscale p – n junctions decreased the hole concentration in the HAL of NiO, leading to the increase in gas response . The change in exposed atomic lattice due to the orientation change from (111) to (200) may have been another contributing factor.…”

Design of Highly Selective Gas Sensors via Physicochemical Modification of Oxide Nanowires: Overview

“…Many studies have been performed on the preparation of nanorods [116,117,118], hollow spheres [119,120], hierarchical nanostructures [121,122,123], and monolayer inverse opals [124] of p -type oxide semiconductors by solution-based routes. In contrast, the growth of p -type oxide semiconductor NWs has been barely investigated.…”