Abstract: Nanomaterials have excellent anomalous, abnormal electrical, optical, mechanical and catalytic properties, opening up new research and application fields for the research of new materials. Zinc oxide has the advantages of low cost, non-toxic and harmless, large band gap width and high electronic excitation energy, and has been widely used in the development of functional devices. However, ZnO has some defects, such as oxygen vacancies (V_o) and zinc deficiency (Zn_i), rapid recombination rate of photoelectron-hole pairs and low adsorption properties. Doping can change the structure of the material and improve its performance. Graphene is a two-dimensional planar structure material with a thickness of only one atomic layer. Its microstructure is a sp² hexagonal atomic network with allotropes of G, GO and rGO. It has a special structure and good properties. Its excellent stability and large specific surface area make it easy to mix with other materials. These properties all help to improve the performance of ZnO nanoparticles. Recent applications of graphene/zinc oxide composite materials in the fields of photocatalysis, sensing, transparent conductive films, optical detection, and electrodes were introduced. The addition of graphene can control defects. The best defects of ZnO/rGO not only increase the surface and carrier concentration of ZnO/rGO but also provide auxiliary carrier paths, supplemented by rGO flakes for electron-hole separation and extended carrier recombination. These characteristics are very suitable for light detection and photocatalysis applications. Due to the high surface area of graphene, a p-n junction is formed between rGO and ZnO nanoparticles. ZnO/rGO composite material has excellent responsiveness and selectivity to gases, and the combination of rGO nanocrystals and ZnO plays a vital role in enhancing detection performance. Adding metal ions and graphene to ZnO can effectively reduce the square resistance of the film. Vacuum annealing and annealing in Ar+H₂ can make electrical properties more excellent because annealing reduces internal defects and disorder. The carrier mobility of graphene at room temperature is about 15 000 cm²/(V·s). Unlike many materials, the electron mobility of graphene is less affected by temperature changes. The optical and electrical parameters of the ZnO/graphene composite film increase the possibility of becoming a transparent conductive electrode. In addition, it can also be used as a photodetector, diode, etc. The composite of ZnO and graphene has a good influence on the development of many fields in the future, and it is still a hot spot and trend of research.

Key words: ZnO, graphene, photocatalytic, gas sensor, transparent conductive film, nanomaterial