Metal–Organic Framework-Derived Porous Hollow Co 3 O 4 /ZnO Nanofibers for H 2 S Sensing

Metal–organic framework (MOF) materials with various shapes and sizes are recognized as outstanding templates for preparing porous metal oxides used as gas-sensitive materials. Here, a facile synthetic strategy is developed to assemble ZIF-67 and ZIF-8 into Co 3 O 4 /ZnO hollow porous nanofibers with an MOF-on-MOF heterojunction for gas-sensing applications. The fabricated sensor using this innovative MOF-on-MOF nanomaterial demonstrates high gas sensor response, low limit of detection, remarkable selectivity, and excellent stability to H 2 S gas. Notably, the Co 3 O 4 /ZnO nanofibers show a maximum response of 50 and 1080 at 200 ppb and 5 ppm of H 2 S under optimal conditions, respectively. Furthermore, the gas-sensing mechanism is proposed in detail, and theoretical calculations based on first-principles further reveal the performance of Co 3 O 4 /ZnO nanofibers in enhancing the sensing of H 2 S. This study offers an approach for fabricating dual MOF-based nanostructures with abundant pores and high surface area for high-performance gas-sensing applications.