Development Of Gas Sensor Based On NiO/WO₃ Heterostructure

Heterogeneous structured gas sensors synthesized from nanomaterials such as tungsten oxide(WO₃)and nickel oxide(NiO)are widely used in various fields of life due to their low cost and ease of synthesis.In this paper,single WO₃ and NiO nanomaterials and NiO/WO₃ nanomaterials containing heterogeneous structures were prepared by hydrothermal method using sodium tungstate dihydrate and nickel chloride hexahydrate as raw materials,and the corresponding WO₃,NiO and NiO/WO₃ heterogeneous structured parathermal gas-sensitive elements were fabricated.The structure,bonding and morphology of the nanomaterials were characterised by XRD,FTIR and SEM,and the performance of the three gas sensors was tested using a home-made laboratory gas-sensitive tester.The optimum operating temperatures for the three gas sensors were 300°C,200°C and 250°C for the WO₃,NiO and NiO/WO₃ heterostructures,respectively.The sensitivity to 300 ppm ethanol at the optimum operating temperature was 124.1,12.57 and 141.9 respectively;corresponding response/recovery times were 20/60 s,35/43 s and 14/15 s.The results show that NiO/WO₃ has improved gas sensor performance over WO₃and NiO and have good repeatability,long-term stability and immunity to other gases.Finally,the gas-sensitive performance is analyzed to be improved,mainly due to the optimization of the morphological structure,the promotion of synergistic catalysis and the presence of heterogeneous structures that modulate the carrier concentration,resulting in a smaller sensor resistance and improved sensitivity.