The favourable synergistic operation of photocatalysis and catalytic oxygen reduction reaction by a novel heterogeneous CoFe2O4-TiO2 nanocomposite

• DOI: 10.1016/j.apsusc.2020.146142
• Publication Date: 2020-03-19T03:47:27Z
• Authors: Qiong Sun; Songhao Wu; Kaijing Li; Bing Han; Yingjie Chen; Beili Pang; Liyan Yu; Lifeng Dong
• Keywords: 7. Clean energy; 01 natural sciences; 0104 chemical sciences

Abstract The improved photocatalytic activity of TiO2 with the addition of spinel CoFe2O4 as an effective catalyst for O2 reduction reaction (ORR) is studied and proved in this study. CoFe2O4-TiO2 heterostructure nanoparticles are prepared by a reflux condensation and two-step hydrolysis-hydrothermal method. The addition of trace CoFe2O4 onto TiO2 can improve its affinity to O2, generate a faster transportation of photo-induced carriers, but hardly affect band structure. With an appropriate amount of CoFe2O4 to TiO2, a remarkable acceleration occurs in photocatalytic decolorization of dye wastewater, and the calculated apparent kinetic constant (kapp) of the composite (0.020 min−1) is 2.4 and 5.6 times of pure TiO2 (0.0085 min−1) and CoFe2O4 (0.0036 min−1), respectively. Quenching experiments with different radical scavengers show that O2–∙ is the key oxidative radical in all photocatalytical reactions. Meanwhile, the rapid growth of O2–∙ production by CoFe2O4-TiO2 is proved to be a major cause for photocatalytic performance improvement. Furthermore, an improved electrochemical ORR catalytic ability by CoFe2O4-TiO2 is verified and the 2-plus-2 electron route generates the same product (H2O2) as the photocatalytic process. Therefore, the synergistic operation of photocatalytic and catalytic ORR process by CoFe2O4-TiO2 resulted in a rapid degradation of dye wastewater.