MIL-100(Fe)/g-C3N4 composites with enhanced photocatalytic activity for UO22+ reduction under visible light.

As a clean energy source, nuclear energy can gradually replace traditional fossil energy sources, and is an important means to achieve the "double carbon goal". Uranium-containing wastewater is inevitable in the development of nuclear energy. The composites MIL/CNx of MOF material MIL-100(Fe) and carbon nitride (CN) were obtained by a simple solvo-thermal method using iron nitrate, homophthalic acid and CN. The material MIL-100(Fe) with high specific surface area was compounded with CN to increase the in-plane adsorption sites, which could adsorb 30% of uranium in solution during the dark reaction. The close interfacial contact of the two materials effectively inhibited the complexation of photo-generated electrons and holes and promotes electron migration. These two synergistic effects improved their overall photocatalytic reduction capacity, which could reduce 97% of UO22+ in solution in 20 min. The UO22+ removal efficiency of MIL/CN0.1 was 2.3 and 1.6 times higher than that of CN and MIL-100(Fe), respectively. In addition, MIL/CN0.1 was stable in reducing uranium during the five cycles of the experiment.