Enhanced photocatalytic activity and mechanism of CeO₂ hollow spheres for tetracycline degradation

Recently, researchers have focused on designing and fabricating highly efficient catalysts for photocatalytic organic pollutant removal. Herein, CeO₂ hollow spheres were prepared through a simple template method followed by calcination at different temperatures for the tetracycline (TC) degradation under simulated solar light illumination. With a calcination temperature ranging from 400 to 800 °C, the as-prepared CeO₂ hollow structure annealed at 600 °C (C₆₀₀) exhibited the best degradation performance with a degradation rate constant of 0.066 min⁻¹, which was about six and five times higher than those of the uncalcined sample (C₀) and the sample calcined at 800 °C (C₈₀₀), respectively. Moreover, sample C₆₀₀ was also superior to the CeO₂ solid particle photocatalyst. The characterisation results showed that the improved photocatalytic performance was mainly ascribed to the synergistic effect of large specific surface areas, high crystallisation and excellent light scattering ability. Furthermore, the results of active species trapping experiments demonstrated that the superoxide anion (•O₂⁻) radical and hole (h⁺) played dominant roles in TC degradation. Subsequently, the possible TC degradation pathways and photocatalytic mechanism of CeO₂ hollow spheres were proposed on the basis of high-performance liquid chromatography–mass spectrometry analysis, main active species and band edge positions of CeO₂. The results of this study provide a basis for designing and exploring hollow structure catalysts for energy conversion and environmental remediation.
近年來，設計和製備高活性光催化劑應用於降解有機污染物領域受到了研究者們的廣泛關注。在此，本工作利用範本法和高溫煅燒法製備了二氧化鈰空心球，並在模擬太陽光照射下將其應用於降解四環素。實驗結果表明：在400-800 °C 煅燒溫度範圍內，600 °C煅燒條件下所得的樣品 (C₆₀₀) 表現出最佳光催化性能，其降解速率常數為0.066 min⁻¹，這一降解速率常數值分別為未煅燒二氧化鈰空心球 (C₀) 的6倍和800 °C煅燒條件下制得二氧化鈰空心球(C₈₀₀)的5倍。同时，該催化劑的光催化性能遠優於二氧化鈰納米顆粒。該增強效應得益於C₆₀₀ 較大的比表面積、高的結晶性、良好的光子捕獲能力。活性物種捕獲實驗揭示了二氧化鈰空心球光催化降解四環素過程中主要活性物種為•O₂⁻和 h⁺。此外，通過對反應過程中間體的測試和二氧化鈰帶隙的表徵，提出了四環素在光催化降解過程中的反應路徑。本工作為設計和探索空心結構催化劑應用於環境修復方面奠定了基礎。Copyright © 2021 Youke Publishing Co., Ltd.