Synergistic Effect of MOF-Derived Porous In2O3 and High-Entropy Alloy for Enhanced Room-Temperature Ammonia Sensing

High-performance room-temperature ammonia (NH3) sensors are highly desirable for environmental monitoring and noninvasive chronic kidney disease diagnosis via breath analysis. Structurally advantageous, metal-organic framework (MOF)-derived metal oxides combined with low-cost, highly catalytic, nonprecious high-entropy alloy (HEA) nanoparticles show great potential for room-temperature gas sensing, yet such composites are rarely explored. Herein, FeCoNiMnCu HEA was rationally coupled with MOF-derived porous In2O3 to fabricate a HEA-modified In2O3 (HEA-IO) composite for room-temperature NH3 sensing. The optimized HEA-IO sensor delivered exceptional anti-interference selectivity and achieved a sensing response of 98.3 to 80 ppm NH3, almost twenty-fold that of pristine MOF-derived In2O3 and other control samples. Furthermore, it also featured rapid response/recovery speed, a low detection limit, humidity resistance, and excellent long-term stability. DFT calculations confirmed that FeCoNiMnCu HEA optimized surface electronic states, promoted NH3 enrichment and catalytic reactions, and accelerated interfacial charge transfer. Raman and TPD characterizations corroborated a unique interfacial synergistic interaction between HEA and MOF-derived In2O3, which was absent in conventional In2O3-based counterparts. The synergistic effect endowed HEA-IO with superior room-temperature NH3 sensing capabilities, enabling promising breath biomarker detection in clinical noninvasive diagnosis.