▎ 摘　　要

Since toxic gas leakage may cause ecological environmental problems and even life-threatening damage, effective monitoring of toxic gas is of great importance and subject to increasing demand. However, complicated environmental factors, as well as various coexisting interferences can easily affect the sensitivity and selectivity of gas sensors, hindering their performance. Recent reports have successfully demonstrated the development of hierarchical nanostructures with desirable self-cleaning properties, yet gas sensors that can resist contamination have rarely been realized. Here, we developed a reentrant thorny ZnO/graphene hybrid nanowall structure that simultaneously repels liquid contamination and possesses NH3 gas sensing properties. The unique reentrant and hierarchical structure, featuring an interconnected vertical graphene nanowall framework with numerous ZnO nanospikes branched on the top nanowall, is highly repellent to liquids, even biofluids with low surface tension. The hierarchical structure consisting of gas sensing graphene and ZnO can be successfully applied as an NH3 gas sensor at room temperature, exhibiting not only excellent sensitivity, selectivity, and repeatability, but also outstanding stability even after bacterial contamination. This study provides a versatile method for fabricating reentrant and hierarchical structures with excellent liquid repellency, and offers a promising method for designing reliable gas sensors with anti-biofouling properties. Gas sensors: a self-cleaning pollution monitorA hybrid nanostructure can simultaneously repel contaminants and possess ammonia-sensing capabilities, making it an ideal pollution monitor. Gaseous pollutants such as ammonia have significant medical and environmental impacts. Hybrid structures of metal oxides and graphene have shown promising gas-sensing performance; however, their utility is hampered by the complexity of air composition and the presence of other contaminants. Xi Xie, of Sun Yat-Sen University, China, led a team of researchers to create a nanostructure of zinc oxide and graphene - both known as ammonia gas-sensitive materials - that repels liquids from its surface. The structure works by trapping "nano-air pockets" on the face of the device that prevent liquids from adhering to it, while the presence or absence of ammonia changes the conductivity of the nanostructure. The researchers' paper shows an effective sensor for use in complicated environments.