Activating Zn Sites of Au/ZnO Nanocages via Au Clusters Enables Highly Sensitive Acetone Detection for Diabetes Screening

Although acetone in exhaled breath is a reliable biomarker for diabetes mellitus, its trace-level detection under high-humidity conditions remains challenging for early noninvasive diagnosis. In this study, Au-loaded ZnO nanocages derived from ZIF-8 were synthesized. The 0.4 wt % Au/ZnO-based sensor exhibits an ultrahigh response of 260.6 toward 40 ppm acetone, a theoretical detection limit as low as 0.468 ppb, fast response/recovery (2/116 s), excellent selectivity, and long-term stability. Moreover, it successfully distinguishes simulated exhaled breath of healthy individuals from that of diabetic patients under 90% RH. Theoretical calculations reveal that Au clusters activate neighboring Zn sites through electronic transfer, enhancing the chemical adsorption capacity of Zn sites for acetone molecules-a mechanism that goes beyond the conventional view of increased adsorbed oxygen. These findings provide new insights into the activation of active sites by noble metal loading and offer a promising strategy for designing highly sensitive and humidity-resistant acetone sensors toward noninvasive diabetes screening.