Functionalization of Mesoporous Semiconductor Metal Oxides for Gas Sensing: Recent Advances and Emerging Challenges

With the emerging of the Internet of Things, chemiresistive gas sensors have been extensively applied in industrial production, food safety, medical diagnosis, and environment detection, etc. Considerable efforts have been devoted to improving the gas-sensing performance through tailoring the structure, functions, defects and electrical conductivity of sensitive materials. Among the numerous sensitive materials, mesoporous semiconductor metal oxides possess unparalleled properties, including tunable pore size, high specific surface area, abundant metal-oxygen bonds, and rapid mass transfer/diffusion behavior (Knudsen diffusion), which have been regarded as the most potential sensitive materials. Herein, the synthesis strategies for mesoporous metal oxides are overviewed, the classical functionalization techniques of sensitive materials are also systemically summarized as a highlight, including construction of mesoporous structure, regulation of micro-nano structure (i.e., heterojunctions), noble metal sensitization (e.g., Au, Pt, Ag, Pd) and heteroatomic doping (e.g., C, N, Si, S). In addition, the structure-function relationship of sensitive materials has been discussed at molecular-atomic level, especially for the chemical sensitization effect, elucidating the interface adsorption/catalytic mechanism. Moreover, the challenges and perspectives are proposed, which will open a new door for the development of intelligent gas sensor in various applications.

Automated summary

With the emergence of the Internet of Things, chemiresistive gas sensors have been extensively applied in various fields such as industrial production, food safety, medical diagnosis, and environment detection. The performance of gas sensors has been improved through the tailoring of sensitive materials' structure, functions, defects, and electrical conductivity. Among these sensitive materials, mesoporous semiconductor metal oxides, with tunable pore size, high specific surface area, abundant metal-oxygen bonds, and rapid mass transfer behavior, have been considered as the most promising. This article provides an overview of the synthesis strategies for mesoporous metal oxides, summarizes the classical functionalization techniques of sensitive materials, discusses the structure-function relationship at the molecular-atomic level, and proposes challenges and future perspectives for the development of intelligent gas sensors.