Tailoring the CeO2 morphology and its electrochemical reactivity for highly sensitive and selective determination of dopamine and epinephrine

Four CeO2 nanomaterials with the morphologies of a nanoplate (CeO2-p), a nanocube (CeO2-c), a porous triangular microplate (CeO2-t), and of a porous hierarchical rod-stacked nanobundle (CeO2-b) were synthesized using a hydrothermal method. They were characterized by scanning and transmission electron microscopies, X-ray diffraction and X-ray photoelectron spectroscopy. Electrochemical characterizations reveal the tuning of their morphology and the presence of exposed crystal planes of CeO2 that can be realized by changing the alkali sources. Among these materials, the CeO2-b features the largest specific surface and lowest electron transfer resistance towards the redox probe Fe(CN)(6)(3-/4-). The best voltammetric response to dopamine and epinephrine is thus achieved by using the Nafion-CeO2-b coated electrode. A sensitive and selective method was developed that can voltammetrically detect dopamine (with a peak near 0.13 V vs. SCE), and epinephrine (with a peak near 0.25 V vs. SCE). The detection limits are 2.9 and 0.67 nM, respectively.