Facile synthesis of N-doped carbon sheets-ZnO hybrids for NO2 sensing at ppb level

Constructing heterostructure and N-doping are two effective methods to improve gas sensing performance. Herein, a facile novel solution calcination strategy has been proposed to synthesize N-doped carbon sheets-zinc oxide (NC-ZnO) hybrids for low concentration NO 2 detection. The formation of NC is accompanied by generation of ZnO particles on its surface to construct heterostructure. Intriguingly, NO 3 - acts as an expanding agent and N source in the calcination process, wherein the N elements are directly doped into carbon sheets. As expected, the prepared heterostructural NC-ZnO-63 hybrids exhibit 74.9 times enhancement of response as well as high sensitivity (~ 265.8–20 ppm NO 2 ), excellent repeatability and selectivity compared with pure ZnO. Importantly, the measured detection limit of the NC-ZnO-63 sensor to NO 2 is about 100 ppb (~ 0.3) and the calculated detection limit is 2.65 ppb. Furthermore, the influences of humidity on testing NO 2 gas have been researched systematically which would provide guidance for practical use of similar sensors. In this work, ZnO and derived carbon are low-cost, eco-friendly, and the synthesis strategy presented here is simple and repeatable, which provides new idea for mass fabricating other-type metal oxides-NC hybrids for various applications.