Low-temperature thermocatalytic particulate carbon decomposition via urea solution-combustion derived CeO2 nanostructures

Abstract

A facile, one-pot, urea solution combustion route was utilized to synthesize highly catalytic CeO2 nanostructures. CeO2 prepared under varying thermal conditions was characterized by electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, infrared and Raman techniques. As the synthesis temperature is raised from 400 to 1000 °C, the crystallite size and d-spacing of nanoparticles are observed to reduce while cell parameters remain in the same range. Particle size exhibits an accession from ∼20 to ∼50 nm along the process. Initial CeO2 nanoparticles are detected as a composite structure of CeO2 and graphitic carbon nitride (g-C3N4) produced by the pyrolysis of urea. Concerning the solid carbon particulate oxidation capacity, an outstanding performance is exhibited by CeO2 synthesized at 800 °C where the oxidation onset temperature is reduced by 27% compared with the others. The superior performance is attributed to the carbon nitride-generated unique CeO2 nanomorphology consolidating ample reactive sites and facilitated oxygen delivery for a highly efficient thermocatalytic process. Concerning atmospheric pollution mitigation, synthesis of these CeO2 nanostructures represents a cost effective and convenient abatement technique for carbon particulates in comparison to cost-intensive, environmentally detrimental and noble-metal based techniques.

Graphical abstract Particulate carbon commonly known as soot is a proven environmental and health hazard in the modern world. Automobile exhaust is a major contributor to the atmospheric soot and prompt action on mitigation of this pollutant is required. Ceria nanoparticles derived by a facile solution combustion in urea facilitated rapid decomposition of particulate carbon at a comparatively lower temperature indicating its superior potential usability in degradation of particulate carbon within the automobile exhaust system curbing the emissions at the source itself.