High Electrochemical Performance and Enhanced Electrocatalytic Behavior of a Hydrothermally Synthesized Highly Crystalline Heterostructure CeO2@NiO Nanocomposite.

A CeO2-based heterostructure nanocomposite has been attractive as an electrode material for energy storage and as an electrochemical sensor. In the present work, a CeO2@NiO nanocomposite was prepared by a simple hydrothermal method. The structural and morphological information on the heterostructure CeO2@NiO nanocomposite were obtained by using different characterization methods like X-ray diffraction, UV-visible, Fourier transform infrared, electron paramagnetic resonance, Raman, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray elemental color mapping, X-ray photoelectron spectroscopy, and thermogravimetric analysis. Compared with pristine CeO2, the heterostructure CeO2@NiO nanocomposite exhibits a higher electrochemical performance with a specific capacitance of 317 F g-1 at a current density of 1 A g-1 in a 1 M KOH electrolyte. This device demonstrates a high energy density and a power density of 11 Wh kg-1 and 750 W kg-1, respectively. Besides, it was found that CeO2@NiO/glassy carbon electrode (GCE) shows appreciable electrocatalytic activity toward NO2- oxidation. The CeO2@NiO-modified electrode displays a linear response for NO2- oxidation between 0.001 × 10-6 and 4 × 10-3 M. Apart from high sensitivity (2260 μA mM-1 cm-2), the CeO2@NiO-modified electrode also exhibits good selectivity and long-term stability for nitrite (NO2-) detection in a water real sample, and the obtained results showed excellent recovery. The encouraging electrochemical performance of the CeO2@NiO nanocomposite provides a promising approach for the development of multifunctional electrode materials for future energy storage devices and sensors.