Synthesis of a Flower-Like g-C(3)N(4)/ZnO Hierarchical Structure with Improved CH(4) Sensing Properties

In this paper, a hierarchical structure of graphite carbon nitride (g-C(3)N(4)) modified ZnO (g-C(3)N(4)/ZnO) was synthesized using a simple precipitation-calcination method. Through this method, g-C(3)N(4) nanosheets with a controlled content were successfully decorated on the petals of flower-like ZnO. Various techniques were used to confirm the successful formation of the g-C(3)N(4)/ZnO hierarchical structure. The methane (CH(4)) sensing properties of g-C(3)N(4)/ZnO sensor were investigated. The result exhibited that after decorating ZnO with g-C(3)N(4), the CH(4) sensing performances of the fabricated sensor were remarkably improved. At the optimum operating temperature of 320 °C, the response of the sensor fabricated with CNZ-3 (the sample with an optimum content of g-C(3)N(4)) towards 1000 ppm CH(4) was as high as 11.9 (R(a)/R(g)), which was about 2.2 times higher than that of the pure ZnO sensor (5.3). In addition, the CNZ-3 sensor also exhibited a fast response/recovery speed (15/28 s) and outstanding long-term stability. The enhancing CH(4) sensing mechanism may be contributed to enlarged surface area, pore structure, and g-C(3)N(4)-ZnO n-n junction.