Controllable synthesis of recyclable core–shell γ-Fe2O3@SnO2 hollow nanoparticles with enhanced photocatalytic and gas sensing properties

Abstract

Composite materials containing different components with well-defined structures may cooperatively enhance their performance and extend their applications. In this work, core–shell γ-Fe₂O₃@SnO₂ hollow nanoparticles (NPs) were synthesized by a low-cost and environmentally friendly seed-mediated hydrothermal method. Firstly, the γ-Fe₂O₃ hollow NPs were synthesized by a template-free method. Then they were used as the cores for the growth of SnO₂ shells. The thickness of the shell can be simply tailored by controlling the reaction time. Various techniques, including SEM, XRD, TEM and HRTEM, were employed to investigate the morphology, structure and formation process of the special core–shell hollow structures. The combination of magnetic semiconductor (γ-Fe₂O₃) and wide band-gap semiconductor (SnO₂) endowed them with great potential to be used as recyclable photocatalysts. Experiments on photo-degradation of Rhodamin B (RhB) dye in the presence of the samples showed that the hybrid structures possessed higher photocatalytic activities than the monomer structures of SnO₂ and γ-Fe₂O₃ materials indicating a strong coupling enhancement effect between the wide and narrow band-gap semiconductors. Moreover, the gas sensing tests of the γ-Fe₂O₃@SnO₂ hollow NPs revealed that the samples exhibited fast response and recovery rates, which enable them to be promising materials for gas sensors.