Bromine doped g-C3N4 with enhanced photocatalytic reduction in U(VI)

In the process of uranium mining and smelting, large quantities of low-concentration uranium-containing wastewater have been produced. It is an ideal solution to remove and recover dissociative uranium from contaminated sites and water systems particularly with the method of photocatalysis. Due to the unique electronic structure and optical properties, graphitic carbon nitrides (g-C3N4) cover ranges of photocatalytic applications in the environment and energy fields. However, g-C3N4 still face some inherent defects, such as high recombination rate of charge carriers, low electrical conductivity and lack of visible-light absorption. In order to improve its light absorption and the efficiency of photocatalytic reduction in uranium, NH4Br was used as the bromide source to conduct bromine doping in g-C3N4. The resulting materials show a smaller band gap, proving an extended light absorption range. Compared with bulk carbon nitride, the efficiency of photocatalytic reduction in uranium is increased by 2.2 times with good stability in five cycles. This study provides an effective strategy to construct a stable and efficient visible-light-responsive photocatalyst in the reduction in radioactive uranium.