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 40 ppm of NO with high reproducibility at temperature as low as 60 °C which is remarkable when compared to previously reported SnO₂ based NO sensors operating at high temperatures (~ 200 °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.