Enhanced Electrical, Optical, and Magnetic Properties in Multifunctional ZnO/α-Fe 2 O 3 Semiconductor Nanoheterostructures by Heterojunction Engineering

Here we report the facile synthesis of 1D ZnO/α-Fe 2 O 3 semiconductor nanoheterostructures (SNHs), and we investigate the strong interfacial interactions at the heterojunction, resulting in novel multifunctional properties. ZnO-coated α-Fe 2 O 3 nanowires (NWs) have been prepared by combining electrodeposition and wet chemical methods. Significant improvement in electrical conductivity, photoluminescence, and room temperature magnetic properties have been observed for the ZnO/α-Fe 2 O 3 SNHs over the pristine α-Fe 2 O 3 NWs because of the contribution of the ZnO nanolayer. The increase in electrical conductivity in ZnO/α-Fe 2 O 3 SNHs is because of the increase in free electrons in the conduction band of the SNHs due to the formation of type-II n-n band configuration at the heterojunction. The SNHs are found to exhibit enhanced visible green photoluminescence along with the UV emission at room temperature. The band-gap emission of the α-Fe 2 O 3 NWs coupled to the defect emissions of the ZnO in SNHs can be attributed to the profound enhancement of the visible green luminescence. Magnetization of the SNHs is found to be increased nearly five times in magnitude over the primeval α-Fe 2 O 3 NWs, which can be ascribed to the exchange coupling of the interfacial spin at ZnO/α-Fe 2 O 3 interface, the surface spin of ZnO nanolayer, along with the structural defects like the cation vacancies ( V Zn ) and the singly ionized oxygen vacancies ( V o • ) present in SNHs.