Hollow Mesoporous ZnO/ZnCo2O4 Based on Ostwald Ripening for H2S Detection

Mesoporous ZnO/ZnCo2O4nanocomposites with excellent gas-sensing performance were synthesized using the Ostwald ripening method. The as-prepared ZnO/ZnCo2O4comprised aggregated monodisperse nanoparticles, and the nanoparticle size grew with increasing thermal treatment temperature. Increasing the calcination temperature did not significantly change the overall size of the ZnO/ZnCo2O4nanocomposites, but the pore size and specific surface area were noticeably affected. The gas-sensing results showed that ZnO/ZnCo2O4composites calcined at 500 °C exhibited the highest response to H2S at 200 °C, with a detection limit of 500 ppb. The ZnO/ZnCo2O4composites also exhibited remarkable selectivity, response/recovery speed, and stability. Their excellent gas-sensing performance might be attributed to their porous structure, large specific surface area, and the heterogeneous interface between ZnO and ZnCo2O4. This work not only represents a new example of the Ostwald ripening-based formation of inorganic hollow structures in a template-free aqueous solution but also provides a novel and efficient sensing material for the detection of H2S gas.