High selectivity methanol sensor based on Co-Fe2O3/ SmFeO3 p-n heterojunction composites

A high-performance methanol gas sensor based on Co-Fe2O3/SmFeO3 p-n heterojunction composite was prepared by sol-gel method with molecular imprinting technology (MIT). The composites were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), respectively. The results indicate that the Co2+/Co3+ entered Fe2O3 by replacing Fe3+ which formed Co-Fe2O3, and constituted p-n heterojunction with SmFeO3. The methanol gas sensing properties of Co-Fe2O3/SmFeO3 were investigated. The formation of Co-Fe2O3/SmFeO3 with MIT exhibited ultrahigh response, quick sensitivity and significant selectivity. The sensor based on Co-Fe2O3/SmFeO3 with MIT to 5 ppm methanol gas at 155°C was 19.7 while the response to other test gases lower than 9. The superior sensing performance of composites attributes to the different Fermi levels of Co-Fe2O3 and SmFeO3 so that the electron delivered across the Co-Fe2O3/SmFeO3 interfaces through band. The results reveal that Co-Fe2O3/SmFeO3 would be a promising methanol gas sensing materials.