A facile pyrolysis synthesis of Ni doped Ce2O3@CeO2/CN composites for adsorption removal of Congo red: Activation of carbon nitride structure.

[Display omitted] • Ni doped Ce 2 O 3 @CeO 2 /CN composite is prepared in pyrolysis by tuning nickel doping. • CeO 2 surface is reduced in air to form Ce 2 O 3 @CeO 2 structure by carbon nitrides. • Carbon nitride structure is activated and positively charged by Ce 2 O 3 @CeO 2 structure. • Ni doped Ce 2 O 3 @CeO 2 /CN composite has highest adsorption capability of Congo red. Sheet-like Ni doped Ce 2 O 3 @CeO 2 /CN composite is synthesized by tuning the introduction of nickel in a facile and low-cost pyrolysis process. Due to the activation of the shell-core Ce 2 O 3 @CeO 2 structure, the nitrogen chemical state in the carbon nitrides is mainly in the form of an N-(C 3) structure, inducing the production of excellent electronic conductivity and positive charges on carbon nitrides. For the pyrolytic synthesis of the composite, the amount of nickel doping is a crucial factor. Under no nickel condition, only CeO 2 is synthesized and positively charged. With increasing nickel content, Ni doped CeO 2 /CN composite is prepared and negatively charged due to its main component of CeO 2 and the change of its carbon nitride structure. Ni doped CeO 2 prepared with high enough nickel content presents individual NiO particles and its negatively charged surface. The removal of these designed composites for anionic Congo red is utilized to reveal the significant influence of their surface structure. Ni doped Ce 2 O 3 @CeO 2 /CN composite depicts the highest removal performance. Ni doped CeO 2 /CN composite, despite the great change in its carbon nitride structure, still has much higher removal efficiency than pure CeO 2. However, Ni doped CeO 2 is found to have lower adsorption performance than pure CeO 2. [ABSTRACT FROM AUTHOR]