Entropy-modulated Fenton-like oxidation driven by in-situ confinement effect for efficient removal of emerging contaminants.

Fenton-like oxidation is often hampered by high energy barriers, uncontrolled oxidation pathways, and inefficient reactive oxygen species (ROS) utilization. Here, we report an energy-driven confined catalytic nanoreactor that leverages the in-situ confinement energy generated within nanopores to fundamentally regulate degradation thermodynamics. Taking sulfamethoxazole (SMX) as a model contaminant, the confined nanoreactor exhibited a 22.11-fold higher kinetic constant (0.157 min-1) and 40 % enhanced mineralization efficiency compared with its non-confined system. The imprinting channel of confined nanoreactor enabled selective adsorption of SMX within the nanochannel, inducing pronounced confinement effects. The resulting confinement energy triggered a low-entropy degradation pathway (ΔS reduced by 3.2 × 103-fold), which broke thermal equilibrium constraints and redirected SMX oxidation along a low-energy-barrier route. The in-situ confinement-induced low-entropy reaction not only accelerated pollutant degradation but also improved ROS conversion efficiency. This study demonstrated a green and sustainable approach to overcome the intrinsic efficiency bottleneck of Fenton-like processes and provide a new perspective on exploiting nanoconfinement effects for environmental remediation.