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.