Facile synthesis of ZnO/Ag/g-C3N4 nanocomposites for multiple applications in photocatalytic degradation and photoactivated NO2 sensing

It is important to seek effective strategies to fabricate nanomaterials with multi-functionalities in noxious gas detection and poisonous waste treatment. Herein, Ag nanoparticles and g-C3N4 nanosheets co-modified ZnO heterostructure was synthesized via a one-step polymer-network gel method, which is used as both photocatalyst and sensing material. Being a visible-light-driven photocatalyst, the ternary ZnO/Ag/g-C3N4 composite produced 100 % Rhodamine B degradation within 30 min with good cycling stability. Besides, the gas sensor based on ZnO/Ag/g-C3N4 exhibited superb room-temperature sensing performance under neutral light excitation, with a response value of 15.3-5 ppm NO2 and a lower detection limitation. The excellent performance was mainly attributed to the significantly enhanced visible-light absorption as well as effectively suppressed charge recombination because of the synergism between the individual components. Moreover, the formation of g-C3N4 nanosheets during thermal oxidation etching plays a critical role in improving the surface area and enriching the surface oxygen vacancies. Thus, this work provides novel insights for the synthesis and multi-applications of ZnO/Ag/g-C3N4 heterostructure with high performance.