Facile cascade-anchored synthesis of ultrahigh metal loading single-atom for significantly improved Fenton-like catalysis.

It is crucial to break the low metal-loading limitation and reveal the intersite synergy-governed catalytic behavior of single-atom catalysts (SACs). Here, a universal synthesis strategy achieves record loadings of transition metals (Fe 41.31 wt%, Mn 35.13 wt%), rare-earth metals (La 28.62 wt%), and noble metals (Ag 27.04 wt%). The strong oxalic acid-metal chelation and concurrent entangled polymer networks enable high-loading SACs. High-density single atoms induce site-intensive effects, modulating electron density and valence states to achieve peroxymonosulfate-based Fenton-like reactions with rate constants 1-2 orders of magnitude higher than conventional SACs. Elevated metal loading boosts Fenton-like potential jumps, facilitates electron transfer, and reduces the rate-limiting energy barrier in 1O2 production. This material is also proven effective in real wastewater treatment, combining high decontamination efficiency with operational stability. It is anticipated that the cascade-anchoring synthesis strategy will take SACs a step closer to practical applications.