Dual Source Electron Transfer Enabled by N-Doped Carbon for Efficient Fe(III) Reduction

The Fe(III)/Fe(II) cycle plays a pivotal role in the Fenton-like process. Conventional strategies relying on external reductants suffer from drawbacks, such as radical self-quenching and secondary pollution. This study innovatively utilized electron-rich pollutants and H2O2 as dual electron donors to accelerate Fe(III) reduction. Nitrogen-doped Ketjen Black (KB-N) was synthesized through pyrolysis modification using guanine, a nitrogen-rich compound with a conjugated structure, as the precursor. KB-N mediated electron transfer from electron-rich pollutants to Fe(III) via its π–π conjugated network, while nitrogen active sites enhanced H2O2 adsorption and facilitated efficient electron extraction through a delocalized π-system for Fe(III) reduction. More importantly, pyridinic N served as a key catalytic site that coordinates with Fe(III), significantly elevating the oxidation potential of Fe(III), thereby promoting H2O2 activation and reducing the reaction energy barrier. KB-N effectively mitigated the substrate specificity of pristine KB and substantially broadened the electron supply sources. This dual-channel electron transfer mechanism enabled efficient and stable Fe(II) regeneration and enhanced contaminant degradation. In contrast to sacrificial electron donor strategies, this study proposed a clean electron transfer mechanism, offering a novel pathway for highly efficient, stable, and sustainable water treatment technologies.