Programmable Control Over Radical and Non‑Radical Pathways in Fenton‑Like Catalysis via Carbon‑Encapsulated Iron Nanoreactors.

To regulate the synergy between radical and nonradical pathways, endowing catalytic systems with programmable pathway switching capability, remains a challenge on Fenton‑like reactions. In this study, we designed a series of carbon‑encapsulated iron‑based core-shell catalysts, and discovered that iron and carbon precursors can serve as catalysts to precisely regulate the geometry and encapsulation degree of the carbon layer. We revealed the universal regulatory mechanisms by which key factors, including the Fe/N sites, carbon geometry, oxidant molecular/electronic structure, and pH condition, act as critical switches to modulate the catalytic pathways. Furthermore, we identified a proton‑coupled electron transfer mechanism involving hydrogen/hydroxide ions for the first time. The radical and non‑radical pathway selection is determined by the cooperative tuning of the carbon work function and the iron d‑band center, which jointly govern adsorption and electron transfer kinetics and thus dictate the matching with the frontier orbitals of oxidants. The dominant catalytic oxidation mechanism ultimately controls the transformation fate of organic pollutants both in solution and on the catalyst surface. The work bridges the gap left by single‑pathway designs and shifts toward systems capable of programmable directional catalysis, providing a rational design principle for adaptive catalytic oxidation in Fenton‑like systems.