Ultrafast Water Purification by Template‐Free Nanoconfined Catalysts Derived from Municipal Sludge

Nanoconfinement at the interface of heterogeneous Fenton‐like catalysts offers promising avenues for advancing oxidation processes in water purification. Herein, we introduce a template‐free strategy for synthesizing nanoconfined catalysts from municipal sludge (S‐NCCs), specifically engineered to optimize reactive oxygen species (ROS) generation and utilization for rapid pollutant degradation. Using selective hydrofluoric acid corrosion, we create an architecture that confines atomically dispersed Fe centers within a micro‐mesoporous carbon matrix in situ. This method maximizes the utilization of silicon and aluminum content from sludge, prevents metal agglomeration, and precisely regulates the chemical environment of Fe active sites. As a result, the S‐NCCs promote a transition from nonradical to hybrid radical/nonradical reaction mechanisms, significantly enhancing ROS efficiency, stability, and pollutant degradation rates. These catalysts demonstrate exceptional pollutant removal performance, achieving a 261‐fold increase in degradation efficiency for compounds such as phenol and sulfamethoxazole compared to unconfined analogs, outperforming most state‐of‐the‐art Fenton‐like systems. Our findings highlight the transformative potential of nanoconfined catalysis in environmental applications, providing an effective and scalable solution for sustainable water purification.