Optimized preparation of nitrogen-modified ceria for stable and efficient degradation of 2,4-DCP

Chlorophenols have been frequently detected in the environment, posing potential threats to both the natural ecosystem and human health. Semiconductor photocatalytic degradation of chlorophenols has become a prominent research focus. However, the development of high-performance and stable photocatalysts remains challenging. In this work, the nitrogen-modified ceria (N-CeO2) was optimally prepared by microwave-assisted method and utilized for photocatalytic degradation of 2,4-DCP. The CeO2 photocatalyst with 10% nitrogen doping (10% N-CeO2) prepared under the optimal condition (microwave power of 560 W for 2 min and calcination temperature of 400 °C for 2 h) degraded 2,4-DCP with the highest removal efficiency of 93.51%. It was identified that the optimally prepared 10% N-CeO2 photocatalyst had the nanometer size with surface imperfections and increased BET surface, and showed strongest photocurrent response and lowest charge transfer resistance among all the prepared materials. Additionally, an analysis of the band gap structure revealed that the band gap of 10% N-CeO2 decreased from 3.05 eV (for pure CeO2) to 2.42 eV, resulting in enhanced light absorption capacity. The radical trapping experiments and electron paramagnetic resonance (EPR) proved that the active species contributed to the degradation of 2,4-DCP mainly as •OH, •O2-. The potential photocatalytic degradation mechanism of 2,4-DCP was a continuous dechlorination and hydroxylation process with complete mineralization of the pollutant to CO2 and H2O. This work can provide a feasible way to prepare high-efficiency nitrogen-doped ceria photocatalysts with great potential for the removal of chlorophenols.