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

Four CeO 2 nanomaterials with the morphologies of a nanoplate (CeO 2 -p), a nanocube (CeO 2 -c), a porous triangular microplate (CeO 2 -t), and of a porous hierarchical rod-stacked nanobundle (CeO 2 -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 CeO 2 that can be realized by changing the alkali sources. Among these materials, the CeO 2 -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-CeO 2 -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. Schematic representation of morphology tailoring of CeO 2 and electrochemical sensing of dopamine and epinephrine on these CeO 2 samples with different morphologies