As the smallest entities in catalysts, single-atom catalysts (SACs) exhibit superior atomic efficiency, advanced activity, and high selectivity. However, their practical applications are inhibited due to their high preparation costs. Here, we developed a novel cobalt− carbon-based SAC derived from the mild pyrolysis of spent coffee grounds soaked in Co (Co-CGBC), in which cobalt atoms atomically disperse and coordinate with the N and S atoms in the carbon substance, as identified by X-ray absorption fine structure (XAFS) spectroscopy combined with high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Co-CGBC is inexpensive and exhibits high efficiency in the activation of peroxymonosulfate (PMS) to degrade a wide range of organic pollutants with a degradation efficiency of 90−100%. Density functional theory (DFT) calculations confirm that the sulfur in the Co−N 3 S 1 active site plays a crucial role in reducing the adsorption energy of PMS and facilitating electron transfer. This work supplies new opportunities to synthesize cost-effective SACs for application in environmental remediation.

An incubation experiment was performed on Potamogeton crispus (P. crispus) using sediment collected from Lake Tangxunhu in the center of China, in order to determine the effects of plant growth on Fe, Si, Cu, Zn, Mn, Mg, P, and Ca concentrations in the sediments and overlying waters. After 3 months of incubation, Ca, Mg, and Si concentrations in the water column were significantly lower, and P and Cu concentrations were significantly higher than in unplanted controls. The effect of P. crispus growth on sediment pore waters and water-extractable elements varied. Concentrations of Ca, Mg, Si, Fe, Cu, and Zn were significantly higher, and P was significantly lower, than in pore waters of the control. Waterextracted concentrations of Fe, Mg, and Si in the sediments were lower, and P was higher, than in the control. Presence of P. crispus generally enhanced concentration gradients of elements between pore waters and overlying waters but not for P. The growth of P. crispus was associated with an increase in water pH and formation of root plaques, resulting in complex effects on the sediment nutritional status.