Peroxymonosulfate Activation by Cobalt-Based Metal–Organic Framework for Rhodamine B Degradation

Developing highly efficient photocatalysts for purifying polluted water and degrading organic contaminants has attracted increasing attention. The generation of singlet oxygen ( 1 O 2 ) and superoxide radicals (O 2 •– ) remains a key challenge for achieving high catalytic performance. Herein, a range of metal–organic frameworks (MOFs), denoted as {[MBPDC)]·H 2 O} n (M = Fe 2+ (MOF 1 ), Co 2+ (MOF 2 ), and Ni 2+ (MOF 3 ); H 2 BPDC = 2,2′-bipyridine-5,5′-dicarboxylic acid), served as an efficient peroxymonosulfate (PMS) activator for the regioselective oxidation of organic pollutants. Photocatalytic experiments revealed that MOF 2 exhibited superior degradation efficiency toward Rhodamine B (RhB), achieving 99.4% removal within 12 min, significantly faster than MOF 1 (4.5%) and MOF 3 (10.0%). Notably, MOF 2 demonstrated excellent reusability and structural robustness over five consecutive cycles. Through integrated radical scavenging tests and electron paramagnetic resonance (EPR) spectroscopy, 1 O 2 and O 2 •– were determined to be the key reactive oxygen species driving the degradation process. The outstanding durability and anti-interference capacity of MOF 2 underscore its practical potential for cost-effective and robust environmental remediation applications.