Co sites induced synergistic effect in hollow Co3O4/ZnO nanocage for enhanced H2S sensing performance.

We have designed hollow Co 3 O 4 /ZnO nanocage by MOFs derived method for detection of H 2 S, which seriously threatens human health. The Co 3 O 4 /ZnO-1 sensor exhibit superior sensing response (R a /R g = 546.2) to 5 ppm H 2 S at 110 °C, which is 32 folds than ZnO sensors with low detection limit (9 ppb), fast recovery (35 s) and high selectivity. Both theoretical and experimental results illustrate the enhanced sensing performance can be attributed to the Co sites induced synergistic effect. [Display omitted] • The hollow Co 3 O 4 /ZnO nanocages have been successfully synthesized. • The state of Co sites in Co 3 O 4 /ZnO can be finely tuned. • The sensor exhibits high response and selectivity at low temperature. • Co sites induced synergistic effect improve sensing performance. Metal organic frameworks (MOFs) derived Co 3 O 4 /ZnO heterostructure has been widely investigated to achieve the high sensing performance. However, the synergistic effects generated from the Co sites and the relationship between the surface structure and sensing performance is still ambiguous. Herein, the hollow Co 3 O 4 /ZnO nanocage heterojunctions have been successfully synthesized, and the state of Co sites can be modulated by finely tuning the coordination environment of Co species. Notably, the Co 3 O 4 /ZnO-1 materials exhibit superior sensing response (R a /R g = 546.2, 32 folds than ZnO sensors) to 5 ppm H 2 S at 110 °C, with low detection limit (9 ppb), fast recovery (35 s) and high selectivity. Detail structural analysis illustrates O 2 can be easily activated around the Co 3 O 4 /ZnO hetero-interface, and the formation of O− species with high mobility improves the surface reaction rate. Additionally, the catalytic reaction between highly dispersed Co species and H 2 S also facilitates the formation of CoS, which can synergistically enlarge the sensing response of sensors. Our work illustrates the state of Co species can greatly affect the sensing performance and pave the way for design of high performance sensing materials. [ABSTRACT FROM AUTHOR]