Magnetic Fe2O3/mesoporous black TiO2 hollow sphere heterojunctions with wide-spectrum response and magnetic separation

The solar-light-harvesting and separation of nanostructured photocatalysts in slurry systems are key issues in fields of photocatalysis. Herein, magnetic Fe2O3/mesoporous black TiO2 hollow sphere heterojunctions (M-Fe2O3/b-TiO2) are fabricated through wet-impregnation and surface hydrogenation strategy, which show wide spectrum response and magnetic separation. The decreased specific surfaces, pore sizes and pore volumes from similar to 80 to 67 m(2) g(-1), similar to 12 to 10.3 nm, and similar to 0.20 to 0.16 cm(3) g(-1), respectively, all confirm the efficient loading of magnetic Fe2O3. The M-Fe2O3/b-TiO2 with narrow bandgap of similar to 2.41 eV extends the photoresponse from UV to near infrared region and exhibits excellent solar-driven photocatalytic degradation performance and long-term stability for complete mineralization methyl orange and high-toxic herbicide metribuzin. The photo catalytic reaction apparent rate constant k for metribuzin is similar to 9 times higher than that of pristine TiO2 under AM 1.5 irradiation. Especially for single-wavelength of 950 nm, the degradation ratio is up to 4%. The enhancement is attributed to Ti3+ and magnetic Fe2O3 with narrow bandgap facilitating solar-light-harvesting, the hollow structure benefiting mass transport, and the heterojunctions favoring the spatial separation of photo generated electron-hole pairs. The magnetic separation is conducive to recycle of photocatalysts, which favors practical applications in environment.