Synergistic catalytic sensitization and oxygen vacancy engineering in MOF-derived Au-ZnO polyhedra for ultrahigh n-butanol sensing

MOF-derived ZnO and Au-ZnO materials were synthesized via a coprecipitation method. • The response value of 0.5 wt% Au-ZnO to 100 ppm n-butanol is 649.77 at 250 °C. • Response time is just one second, enabling real-time detection of n-butanol. • This sensor has a low detectable concentration, excellent selectivity and stability. N-butanol is a flammable volatile organic compound (VOCs) posing potential threats to human health and environmental quality, making its real-time detection critically important. Although Au-functionalized MOF-derived ZnO has been investigated for gas sensing, the influence of Au loading on surface-defect regulation and n-butanol sensing behavior remains insufficiently understood. Herein, porous ZnO rhombic dodecahedra derived from ZIF-8 were functionalized with controlled Au loadings of 0.25, 0.5, and 0.75 wt%. The optimized 0.5 wt% Au-ZnO sensor exhibited a response of 649.77 and a response time of 1 s towards 100 ppm n-butanol at 250 °C, with the response being approximately 3.6 times that of pristine ZnO. A measurable response of 1.41 was obtained at 50 ppb, representing the lowest experimentally verified concentration in this study. The sensor also demonstrated good selectivity, repeatability, and long-term stability. XPS analysis showed that the 0.5 wt% Au-ZnO sample possessed the highest relative oxygen-vacancy content of 34.8%. DFT calculations further suggested a stronger adsorption tendency of n-butanol on the Au-ZnO surface than on pristine ZnO. These results demonstrate that controlled Au loading provides a favorable balance among interfacial charge modulation, oxygen-vacancy regulation, catalytic activity, and adsorption-desorption kinetics. The dodecahedral structure of the MOF-derived ZnO confers high sensitivity to n-butanol on the sensor, providing uniform anchoring sites for gold nanoparticles (Au NPs). Through Schottky barrier modulation, catalytic effects and oxygen vacancy enhancement, the modification with Au NPs further improves the capture efficiency and signal amplification for n-butanol concentrations in the ppb range. Download: Download high-res image (231KB) Download: Download full-size image