Efficient exfoliation of g-C3N4 and NO2 sensing behavior of graphene/g-C3N4 nanocomposite

• DOI: 10.1016/j.snb.2017.01.199
• Publication Date: 2017-02-02T09:01:18Z
• Authors: Nguyen Thuy Hang; Shaolin Zhang; Woochul Yang
• Keywords: 13. Climate action; 02 engineering and technology; 0210 nano-technology; 01 natural sciences; 0104 chemical sciences

Abstract In this work, graphitic carbon nitride (g-C 3 N 4 ) nanosheets were prepared and employed to improve the gas sensitivity performance of graphene. g-C 3 N 4 nanosheets (NS-CN) were exfoliated from bulk powder using a proton-enhanced liquid-phase exfoliation method, where the co-ordinate bonds between nitrogen of g-C 3 N 4 and proton H + of HCl benefit the swelling of bulk and improve the delamination process. The thickness and size of the exfoliated nanosheets were about ∼4 nm and 1–2 μm, respectively. A slight increment of the bandgap of g-C 3 N 4 was observed after exfoliation. It was found that the proton functionalization of g-C 3 N 4 powder before exfoliation facilitates the production of uniform nanosheets. A certain amount ranging from 0% to 90% of as-prepared g-C 3 N 4 was added to a graphene solution and ultrasonically mixed to prepare a graphene/g-C 3 N 4 nanocomposite (G/NS-CN). The performances of pure graphene-based and nanocomposite-based sensors in sensing NO 2 gas were systematically investigated and compared. We found compositing g-C 3 N 4 with graphene significantly enhanced the sensing performance of the graphene sensor. A trade-off effect on sensing response was observed as the weight ratio of NS-CN to graphene in the nanocomposite sensor was changed, suggesting the specific roles of g-C 3 N 4 and graphene in sensing behavior. It was found that the nanocomposite sensor with 15 wt% of NS-CN exhibited the best sensing response. The sensor in this optimized composition presented a linear and stable response as well as good recovery toward NO 2 gas. The sensing mechanism of the nanocomposite sensor was also proposed.