Efficient Degradationof Trimethylamine via VacuumUltraviolet Irradiation with Morphology-Tuned CeO₂

Trimethylamine (TMA) is a common malodorous compound that poses serious environmental and health risks. Four different structures of cerium oxide (CeO₂), namely, cubes, hollow spheres, octahedrons, and spindles, were successfully synthesized via a hydrothermal method and then used for TMA degradation in a vacuum ultraviolet photocatalytic oxidation system. All the synthesized catalysts exhibited enhanced activity compared with commercial CeO₂. The hollow-sphere CeO₂ demonstrated high catalytic performance, achieving 75.9% mineralization of TMA within 90 min and substantially reduced ozone generation (stable 0 ppm in outlet). Additionally, the total outlet concentration of secondary nitrogenous pollutants (NO_<i>x</i> and NH₃) remained below 2.5 ppm. In situ infrared spectroscopy was employed to elucidate the degradation pathway of TMA under vacuum ultraviolet irradiation, comparing sphere CeO₂ with commercial CeO₂. The superior TMA degradation performance of the hollow-sphere CeO₂ was attributed to its higher Ce³⁺ ratio as well as increased oxygen, increased charge separation efficiency, and radical generation. This study provides new insights into the optimization of CeO₂-based photocatalysts to efficiently degrade TMA and offers promising solutions for odor control and environmental protection.