Single-atom Rh catalysts for efficiently degrading Rhodamine B with high concentration

Highly concentrated dye wastewater has a serious effect on the quality of natural waters; thus, developing novel catalysts to degrade dyes rapidly and efficiently is of great significance. For the first time, this study reports an Rh single atom loaded on a nitrogen-doped carbon (SA-Rh/CN) catalyst. This catalyst exhibits an excellent processing capacity for high concentrations of Rhodamine B (RhB), high catalytic activity (95.7% degradation of RhB in 60 min) and excellent stability (93.5% degradation efficiency after 10 stable runs), all over a wide range of pH values (effective from pH 3 to 9), for the degradation of RhB. Using free radical capture experiments, SA-Rh/CN was confirmed to catalyse peroxymonosulphate to produce SO₄·⁻ and ·OH, which played important roles in the degradation of RhB. When SA-Rh/CN was generalised for the catalytic degradation of methylene blue, it also achieved excellent performance. Therefore, this study widens the applications of single-atom catalysts for Fenton-like reactions and demonstrates the potential of single-atom Rh catalysts in wastewater treatment.