MOF-derived In2O3/TiO2 S-scheme heterojunction for efficient photocatalytic degradation of tetracycline

It is challenging to engineer a photocatalyst that can degrade antibiotics efficiently. We have successfully developed a series of photocatalysts by annealing In-MOF (BUT-205) with TiO 2 , namely (a) In 2 O 3 /TiO 2 -I, (b) In 2 O 3 /TiO 2 -II, and (c) In 2 O 3 /TiO 2 -III. These catalysts, particularly In 2 O 3 /TiO 2 -III, exhibited superior efficiency in degrading tetracycline (TC) under visible light. The enhanced photocatalytic performance of In 2 O 3 /TiO 2 -III can be attributed to the formed S-scheme heterojunction, which promoting the separation of electron-hole pairs. The S-scheme heterojunction was confirmed by XPS , in-situ XPS, UV–vis diffuse reflectance spectroscopy, and Mott-Schottky plot, etc. Compared to pure TiO 2 and In 2 O 3 , the In 2 O 3 /TiO 2 -III demonstrated an 18-fold and 3-fold higher degradation rate constant (k). Various factors affecting the degradation of TC were investigated, including pollutant concentration, catalyst type, solution pH, catalyst dosage, inorganic anions , inorganic cations , and radical species. Photoluminescence (PL) and transient photocurrent density evaluate the separation rate of electron-hole pairs, and EPR experiments (active species trapping) studies confirmed •O 2 − and h + as the primary entities in TC photodegradation by In 2 O 3 /TiO 2 -III. HPLC/MS analysis revealed the photocatalytic degradation pathway. The MOF-derived photocatalysts efficiency in TC photoreduction results from the formed S-scheme heterojunction, making it a promising candidate for environmental remediation.