Facile synthesis of mesoporous anatase/rutile/hematite triple heterojunctions for superior heterogeneous photo-Fenton catalysis

Nanostructured heterojunctions with precisely controlled crystal phases, electronic structures and optical properties are crucial for heterogeneous photo-Fenton catalysis. Herein, mesoporous anatase/rutile/hematite (ARH) triple heterojunctions are synthesized via the facile spray-drying forced assembly approach. They possess intimate phase boundaries, abundant oxygen vacancies (OVs), high surface areas (117.6 m(2) g(-1)) and uniform mesopores (3.9-5.1 nm), and wrinkled morphologies. They are superior in heterogeneous photo-Fenton catalysis. With a low H2O2 dosage (3.9 mM) and a weak UV light irradiation (2.0 mW cm(-2)) under near neutral pH, methylene blue (20 mg L-1) can be degraded in 5 min and fully mineralized in 30 min. The structure-performance correlations and influencing factors on performance are studied. The intimate ARE heterojunctions with abundant OVs and a high mesoporosity render enhanced light absorption, charge separation and Fe(III)/ Fe (ID transformation, boosting the activation of H2O2 to generate reactive radicals for fast mineralization.