Pt/Au core–shell nanoparticles decorated ZIF-8–derived ZnO thin films for acetone detection

Detecting acetone is essential for non-invasive medical diagnostics, as it has been recognized as a biomarker for conditions like diabetes and lung cancer. Chemiresistive gas sensors based on metal oxide semiconductors (MOSs) are promising candidates due to their simplicity, low cost, and high sensitivity. Metal–organic frameworks (MOFs), with their high surface area and tunable porosity, have been widely used as precursors to synthesize porous, nanostructured MOSs with enhanced sensing efficiency. The addition of noble metal catalysts such as Au and Pt further improves performance by enhancing surface reactions and charge transfer. In this work, we report a novel strategy for developing acetone gas sensors using noble metal-decorated MOF-derived MOS thin films. Pt–Au core–shell decorated ZnO thin films were fabricated from ZIF-8 through a combination of DC sputtering and in-situ growth. ZnO thin films were initially deposited using DC magnetron sputtering, followed by the growth of ZIF-8 on the ZnO surface, resulting in the formation of a ZIF-8/ZnO composite. Subsequently, layers of Au and Pt were deposited sequentially, and the structure was subjected to heat treatment to create a Pt/Au core–shell configuration on the ZnO derived from ZIF-8. To enhance performance, the thickness of the Pt shell was systematically varied. The optimized sensor, featuring a 20-s Pt deposition over a 40-s Au layer, demonstrated a remarkable response of 24.8% to 0.5 ppm acetone at 250 °C, with rapid response and recovery times of 80 s and 55 s, respectively.