Monodispersed ultra-thin BiOCl nanosheets with (110) facets exposed in situ self-assembled on reduced graphene oxide to enhance NO2 sensing performance at room temperature

In order to effectively increase gas adsorption active sites and boost the electrical conductivity of the materials, we synthesized ultra-thin BiOCl nanosheets with the uniform dispersion on reduced graphene oxide by a facile hot-injection method for detection of the concentration of the pollutant NO2. The size of BiOCl nanosheet was controlled within 25–30 nm. TEM, EPR and XPS unveil the presence of oxygen vacancy (VO) in the composite. The optimum BiG-3 sensor (the mass ratio of BiOCl/rGO is 1/3) exhibits a high sensitivity, elevated selectivity and remarkable long-term stability with the response (S = Ra/Rg) of 12.95–5 ppm NO2, response/recovery time of 9.3 s and 63 s, and as long as 60 days of stability at room temperature. The significant improvement in gas sensing performance of BiG-3 nanocomposite was mainly due to the highest selectivity with the higher adsorption energy of highly exposed (110) crystal planes for NO2, and a large number of oxygen vacancies providing additional active sites. Large areas of effective contact between ultra-thin BiOCl nanosheets and rGO can synergistically promote electron transport. Hence, the high sensing performance sensing material may be inspirations for actual productions. [Display omitted] •Ultra-thin BiOCl nanosheets with rich oxygen vacancies was obtained via by a simple hot-injection strategy.•Both the highly dispersed on rGO and oxygen-rich holes can significantly improve the gas sensitivity to NO2.•NO2 gas sensing mechanism of oxygen vacancy over BiOCl/rGO was revealed.•Optimized BiOCl/rGO sensor presents high sensitivity (12.95), fast response and recovery time (9.3/63.0 s) to 5 ppm NO2.