Catalytic Activation Function of Noble-Metal-Free High-Entropy Alloy for Enhancing SnO₂ Acetone Detection Capability

Enhancing the gas-sensing properties of metal oxide semiconductors using noble metals' electronic and chemical sensitization functions is a common approach to develop high-performance gas sensors. However, the high cost and scarcity of noble metals pose challenges to sustainability. In this study, a non-noble metal MnFeCoNiCu high-entropy alloy (HEA) was designed as an alternative to noble metals to enhance the sensitivity of SnO₂ and enable efficient, stable, and rapid detection of acetone (C₃H₆O). The MnFeCoNiCu HEA-loaded SnO₂ demonstrated improved performance in C₃H₆O detection, including high selectivity (κ > 3), a high sensitivity (<i>R</i>_a/<i>R</i>_g = 4.17 at 0.5 ppm), a low detection limit (30 ppb), fast response and recovery time (4.6 s/5 s), long-term stability (over 50 days), and resistance to humidity (stable at 90% RH). The enhanced performance of the HEA is attributed to the fact that it possesses more valence electrons and the electrons can transfer and redistribute among different atoms, which leads to an increase in active oxygen species and catalytic sites, promoting electron sensitization. This study provides insights into designing and developing a highly catalytic, non-noble metal HEA for gas-sensing applications.