Fc-COOH modified MIL-101(Cr) as enhanced photocatalyst to efficiently degrade tetracycline under visible light

MIL-101(Cr) is an ideal material for wastewater treatment due to its large specific surface area, excellent water stability, and chemical stability. However, its limited light absorption capacity hinders its application. We loaded ferrocene carboxylic acid (Fc-COOH) onto MIL-101(Cr) by a post-synthetic modification method, which resulted in the MOF possessing excellent optical properties while maintaining its original skeleton structure. The MIL-101(Cr)/Fc-COOH (1:2), (abbreviated as CFCC-2) exhibited the best performance, achieving a removal rate of 96% for tetracycline (TC) in just 30 min. This removal rate is significantly higher compared to MIL-101(Cr) and Fc-COOH, which achieved removal rates of only 15% and 21%, respectively. We propose a possible Z-type heterojunction mechanism between MIL-101(Cr) and Fc-COOH to explain the excellent photocatalytic performance of CFCC-2. The intermediates in TC were identified using LC-MS, and the toxicity of these intermediates was predicted and evaluated through the Toxicity Estimation Software Tool (T.E.S.T.). This study provides new insights into the design and fabrication of MIL-101(Cr)-based catalysts as photodegrading organic pollutants.