Development of a Novel Mixed-Metal–Organic Framework: An Innovative Photocatalyst for Simultaneous Cr(VI) Reduction and Phenol Degradation

The direct use of sunlight as an infinite source of energy for wastewater treatment is an overwhelming idea. For this aim, the development of novel and practical photocatalysts has been the main challenge of researchers. Among the different methodologies used, the introduction of multifunctional MOFs as photocatalysts shows a great deal of potential. Here, a simple and useful approach for the synthesis of rare mixed-valence, mixed-metal organic frameworks (MM-MOF) [Fe₂CoO(TPBTM₆)(H₂O)₃]_n (Fe₂CoMOF) [H₆TPBTM: N,N′,N″-Tris(isophthalyl)-1,3,5-benzenetricarboxamide] was investigated using a one-step hydrothermal approach. Applying mixed-metal clusters as preformed SBUs introduces multifunctionality into the MOF structure, leading to high performance in wastewater treatment. The coexistence of Fe³⁺ and Co²⁺ leads to super photocatalytic ability of the structure. Therefore, the catalytic activity of Fe₂CoMOF was explored for concurrent photocatalytic Cr(VI) reduction and phenol degradation. For a better understanding of the cooperative reaction among Cr(VI) reduction and phenol oxidation, methodical tests were conducted to disclose the Cr(VI), phenol, and MOF functions in the photocatalytic procedures. The influence of the primary substrate concentration and pH on the reduction procedure was also examined empirically.