Strategies to boost chemiresistive sensing performance of In2O3-based gas sensors: an overview

Abstract

The development of effective and efficient materials for the selective and sensitive detection of toxic gases and volatile organic compounds is crucial for protecting human health and the environment. In this respect, a well-known n-type semiconducting material, namely indium oxide (In₂O₃), has attracted significant attention because of its gas-sensing applications. The rapid advances in various synthesis techniques have enabled researchers to explore numerous novel nanostructures and their integration into smart gas-sensing devices. Despite sustainable development, the application of In₂O₃ in gas sensing is limited by its poor selectivity, high working temperature, and response deterioration under humid conditions. This review outlines various strategies, such as morphology and interface engineering, catalytic functionalization, shell structure and thickness, and doping, for improving the gas detection performance of In₂O₃-based chemiresistive gas sensors. The significant influence of the nanostructures with different morphologies on the gas-sensing performance of In₂O₃-based sensors is also demonstrated. Pristine In₂O₃ nanomaterials with zero-dimensional (0D) to three-dimensional (3D) morphologies are reviewed. Different composites of In₂O₃, including In₂O₃/metal oxides (p-type and n-type), In₂O₃/noble metal loading and encapsulation, In₂O₃/elemental doping, In₂O₃/conducting polymers, and In₂O₃/carbonaceous materials, were evaluated to improve their sensing performances. Finally, a future outlook on the further progress of the In₂O₃ gas sensors is suggested.