Superior ethanol-sensing properties based on Ni-doped SnO2 p–n heterojunction hollow spheres

This paper reported a novel sensing material of porous Ni-doped SnO2 hollow spheres with nanoheterostructures, which were synthesized by a low-cost and environment-friendly hydrothermal strategy. In the process of synthesis, long-chain polymers nickel nitrilotriacetic acid (NiNTA) were formed previously and then successfully heteroconnected with SnO2 through a series of hydrothermal reactions for the reason that nitrilotriacetic acid (NTA) could be dissolved in the aqueous solution of NaSnO3, leading to the complete change of previous morphology. The response of the sensor based on porous Ni-doped SnO2 hollow spheres is up to 59 at 100 ppm ethanol and the detection limit can be dropped to 1 ppm-level, which exhibits enhanced response compared with many ethanol sensors based on pure SnO2 hollow spheres. Such good performance is probably attributed to the formation of p–n junctions between NiO and SnO2, which increase the resistance of sensor and the depletion layers.