Real-time and sensitive detection of methane (CH₄) is vital to the safety of life and production due to the explosivity and greenhouse effect of methane. Currently, metal oxide semiconductor (MOS)-based chemiresistive sensors are considered as an effective approach for their low cost, highly tunable structures, and easy fabrication. However, disadvantages like high working temperature, low sensitivity, and unsatisfying selectivity limit their potential wide application. In order to achieve the goal of high-performance MOS-based methane sensors, in this review, from the basic mechanism of MOS-based gas sensing and the property of methane, possible strategies of improving methane sensing performances in multiple aspects have been summarized systematically, including sensitivity, selectivity, stability, and humidity resistance. Recent progress in the research and development of metal oxide semiconductor-based methane sensor technology is also surveyed in this review. Finally, the future trends and perspectives of MOS-based chemiresistive methane sensors are proposed.

γ-AlOOH whisker is one of the most popular precursors for the formation of Al₂O₃ whisker. In this paper, a facile hydrothermal method was developed to prepare γ-AlOOH whiskers, using hydrated alumina with different crystallinity as the hydrothermal precursors. Amorphous hydrated alumina precursors were prepared by mixing HCl and NaAlO₂ at room temperature, while crystalline hydrated alumina precursors were produced by precipitation of NaAlO₂ solution. γ-AlOOH whiskers with a length of 800-1500 nm and a diameter of 20-40 nm were formed by hydrothermal treatment (220 ℃, 8.0 h) of the mixing of two kinds of precursors. The experimental results indicated that the different dissolving rates of hydrated alumina precursors were one of the main reasons for the formation of γ-AlOOH whiskers with high aspect ratio.