Construction of Cerium–Titanium Bimetallic NH 2 -MIL-125 for Photocatalytic Reduction of Cr(VI)

To address environmental pollution caused by excessive levels of highly toxic Cr(VI) in wastewater, NH2-MIL-125(Ce/Ti) bimetallic materials with various Ce/Ti ratios were prepared via a one-step solvothermal method to improve the photocatalytic reduction of Cr(VI). The incorporation of Ce not only introduced dual redox-active centers (Ti4+/Ti3+ and Ce4+/Ce3+) but also established a synergistic dual-charge-transfer pathway, markedly accelerating interfacial electron migration and suppressing charge recombination. Among these, the NH2-MIL-125(Ce/Ti) 1:2 photocatalyst exhibited the best visible-light catalytic performance, achieving a Cr(VI) reduction efficiency of 98.7% after 40 min of illumination. This represents approximately a 3.2-fold improvement over untreated NH2-MIL-125(Ti) and retained high activity even after four cycling experiments.