Research PaperEnhanced gas sensing by amorphous double-shell Fe2O3 hollow nanospheres functionalized with PdO nanoparticles

•Double-shell PdO nanoparticles decorated Fe2O3 hollow nanospheres can directly be synthesized using a facile template-free hydrothermal route combined with subsequent annealing process.•Notably, the internal structure of Fe2O3 hollow spheres could be controlled by varying the reaction time.•The gas sensing devices fabricated from PdO loading Fe2O3 hollow nanospheres with double shell structure showed good selectivity to acetone.

Amorphous double-shell Fe2O3 hollow nanospheres decorated with PdO nanoparticles were synthesized via a template-free hydrothermal method combined with subsequent annealing process. The chemical composition and microstructure evolution were examined using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and transmission electron microscope (TEM). Interestingly, the internal structure of hollow spheres could be controlled by varying the reaction time. The formation of such structures was attributed to the combined effect of ripening and hydrogen ions etching process. The sensing properties of Fe2O3 hollow nanospheres before and after functionalization with PdO nanoparticles were investigated. The PdO-loaded Fe2O3 sensor exhibited obviously enhanced response to acetone compared with their unloaded counterparts. The improvement may arise from unique structure and catalytic effect of PdO in promoting the dissociation of gas molecules.