ZIF-8-induced selectivity reprogramming of Co₃O₄ nanorod arrays for ethanol sensing

Developing ethanol-selective gas sensors remains challenging because structurally and chemically related volatile organic compounds (VOCs) often induce similar responses on semiconductor metal oxide surfaces. Here, we report a zeolitic imidazolate framework-8 (ZIF-8)-enabled strategy for reprogramming gas selectivity rather than simple response enhancement by constructing Co₃O₄@ZIF-8 core–shell nanorod arrays. The ZIF-8 layer was deposited on Co₃O₄ nanorods through a seed-assisted conversion route to regulate gas transport and interfacial adsorption. Compared with pristine Co₃O₄ sensor, ZIF-8 functionalization induced a distinct selectivity shift from acetone-preferred to ethanol-preferred sensing (8.7 toward 100 ppm ethanol at 225 °C) and improved humidity tolerance due to the hydrophobicity of ZIF-8. Density functional theory (DFT) calculations revealed stronger ethanol adsorption on ZIF-8 than acetone adsorption, supporting preferential ethanol enrichment within the ZIF-8 shell. This work establishes ZIF-8 functionalization as an effective route for engineering ethanol selectivity in Co₃O₄ sensors and provides insight into MOF-assisted selectivity reprogramming in MOS chemiresistive gas sensors. Download: Download high-res image (187KB) Download: Download full-size image