In the early 2000s, Zhao's group reported that visible light can accelerate the degradation of organic pollutants with aqueous
solutions of iron tetrasulfophthalocyanine ([Fe(PcS)]) and Hydrogen peroxide|. They also found out FeBR (Fe complex of 2,2′-bipyridine) is efficient in eliminating organic pollutants such as rhodamine B (RhB), malachite green (MG) and N, N-dimethylaniline (DMA). They did several control experiments, in the dark or under irradiation, with or without irradiation. They proposed that when light is introduced, excitation of [Fe(PcS)] can result in electron transfer from ligand(L) to Fe, then Fe can be reduced to Fe. The Fe-L complex can react with  to produce HO, leading to the degradation of pollutants.