Gold embedded maghemite hybrid nanowires and their gas sensing properties.

Well-defined gold embedded maghemite hybrid nanowires are synthesized, and their structures are fully characterized. They are composed of porous γ-Fe2O3 shells and embedded gold nanoparticles (3–10 nm), which is novel and very different from the conventional “surface decoration” configuration. These hybrid nanowires are produced by the de-alloying of Au–Fe alloy nanowires and subsequent heat treatment. The reaction mechanism is proposed and validated. The results of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and thermogravimetry techniques prove consistently that the Fe composition of Au–Fe alloy nanowires change to γ-FeOOH first and then to γ-Fe2O3. The embedded gold particles are help to enhance the gas response properties of the hybrid nanowires, which is attributed to the nano open-circuit Schottky junctions between γ-Fe2O3 and the Au nanoparticles. The gas sensing experiment data with high repeatability demonstrate that these hybrid nanowires are excellent sens...