Advances in In2O3-based materials for the development of hydrogen sulfide sensors

Abstract

The presence of H2S is an incisive indicator to assess the quality of indoor and/or outdoor air. A number of metal oxide sensors have been developed to measure the concentration levels of H2S in the environmental systems. Among such sensors, In2O3-based sensors are one of the most promising options with the enhanced potential to generate highly sensitive and specific signals in diverse physical/chemical forms (such as pristine, metal-doped/loaded, and composite). Their enhanced sensing performance has been ascribed to many excellent properties (e.g., chemisorption capabilities of oxygen, direct interactions with H2S, synergetic effect with other materials, generation of sensing signals (at ambient conditions), and capabilities to interact with hydrolyzed form of H2S). It is also noted that chemoresistive sensing of In2O3-materials is a highly preferable option in terms of the strong interactivity with H2S. Herein, we have reviewed the potential of In2O3-based materials (e.g., in pure, metaldoped/loaded, and composite form) for the sensing of H2S gas with the special emphasis on operation temperature conditions (e.g., at and above room temperature). Discussion is also extended to the H2S sensing mechanisms and synthesis procedures with the future prospects on this technology. Moreover, a careful evaluation has been made to select the best available option for the In2O3-based sensing method based on the evaluation on their performance on parallel basis.