Single-Phase Spinel High-Entropy (FeCoNiCrMn) <sub>3</sub> O <sub>4</sub> Synthesized Using Electrospinning Technique and Its Application in the Sensing of Trimethylamine Gas at Room Temperature
Jie Huo, Bosen Zhang, Hongli Zhu, Huiyu Lu, Jiarui Qi, Xinyu Meng, Shuangming Wang, Jing Cao, Longlong Fan
Abstract
High-entropy engineering strategies have achieved success in enhancing energy storage and catalytic performances but are rarely reported to improve gas-sensing dynamics, especially for room-temperature gas sensing. Herein, single-phase spinel high-entropy oxide (FeCoNiCrMn) 3 O 4 has been synthesized by electrospinning and authenticated by XRD Rietveld refinement simulation, configuration entropy calculation, and element mapping. For the first time, the as-prepared alkalized high-entropy oxide (FeCoNiCrMn) 3 O 4 shows room-temperature trimethylamine gas-sensing properties, including superior sensing response (113%), high gas selectivity, fast response/recovery speed (11 s/28 s), as well as preferable repeatability and reliability toward 500 ppm of trimethylamine gas. Gas-sensing tests of comparative samples obtained by replacing and reducing metal ions validate that the synergistic effect by Fe, Co, Ni, Cr, and Mn ions enables (FeCoNiCrMn) 3 O 4 to exhibit room-temperature trimethylamine gas sensing, while more lattice distortion, adsorbed oxygen, and oxygen vacancies generated by alkalization treatment further heighten trimethylamine gas adsorption and catalyze surface gas-sensing reactions. The coupling of high entropy and alkalization strategy opens up a new path for improving room-temperature gas sensing.