Near room temperature sensing of nitric oxide using SnO2/Ni-decorated natural cellulosic graphene nanohybrid film

In recent years, metal oxide nanoparticles and their composites with graphene have received significant research attention in toxic gas sensor applications. Herein, we demonstrate a novel approach to develop a sensor by combining SnO2 nanoparticles and Ni-decorated natural cellulosic graphene (Ni-NCG) derived from lotus petals to form SnO2/Ni-NCG nanohybrid. The morphology, microstructure and elemental composition of the nanohybrids were investigated by a number of techniques which confirmed presence of nanometer sized SnO2 particles having large surface area on sheets of few layered Ni-decorated NCG. Upto 15% response was observed when exposed to 40ppm of NO with high reproducibility at temperature as low as 60 degrees C which is remarkable when compared to previously reported SnO2 based NO sensors operating at high temperatures (similar to 200 degrees C or more). Further, the nanohybrid showed excellent selectivity to NO when tested against other gases. A mechanism have been proposed for the improved sensitivity at low temperature based on the improved surface area of SnO2 nanoparticles leading to larger adsorption of gas molecules combined with an improved conduction of charges provided by the Ni-decorated NCG network. The results show enormous potential for the SnO2/Ni-NCG nanohybrid film as near room temperature NO sensor.