Engineering ceria oxide with nickel doping and rich oxygen vacancies for enhanced electrocatalytic degradation of aromatic organics

Aromatic dyes are widely applicable in the textile, leather, and ink industries yet receive serious contamination issues to water bodies, soil, and even air. Herein, we develop an efficient electrocatalytic oxidation method for degrading aromatic dyes via developing supportive CeO₂-based electrode materials decorating with highly dispersive Ni and rich oxygen vacancies. The decorating Ni species are in situ converted from a composite of CeO₂ nanocrystals and formamide-derived polyaminoimidazole (PAI)-coordinated Ni to ensure the high dispersion of Ni species. The decomposition of PAI ligands also helps to create the localized reductive atmosphere for the generation of rich surface oxygen vacancies, which further benefits the enhancement of electronic conductivity and charge transport ability. The effects of Ni doping concentrations, Rhodamine B (RhB, as a simulating aromatic dye) concentrations, pH of RhB solution, types and concentrations of electrolytes, and working current densities on the degradation performance are comprehensively investigated. Electrocatalytic measurements reveal that the CeO₂ catalyst with optimal Ni concentration and fine single-crystal sizes of 5.5 ± 0.03 nm (termed as Ni_0.025-CeO_2-x) exhibits very promising degradation efficiency (96.9 %) and structural durability (repeated use for 5 cycles with limited activity decrease).