Dynamic chloride coordination enables selective pulsed electrocatalytic upcycling of 4-chlorophenol on FeN₂O₂ single-atom catalyst.

Abstract

The electrocatalytic upcycling of halogenated pollutants into value-added chemicals presents a sustainable frontier, yet precise transformation pathways remain challenging. Here, we report a pulsed electrocatalytic strategy that exploits a temporal modulation to realize a dynamic coordination mechanism, enabling the sequential conversion of 4-chlorophenol (4-CP) to para-benzoquinone (p-BQ) over an N, O-dual coordinated Fe single-atom catalyst (FeN₂O₂ SAC). Diverging from conventional continuous electrolysis, pulsed catalysis spatiotemporally decouples cathodic dechlorination and anodic oxidation, exerting precise control over transient intermediate populations. In situ spectroscopy and density functional theory reveal that pulse polarization drives a dynamic chloride-coordination process at the Fe center. This transient ligand-field modulation optimizes the adsorption energetics and lowers the thermodynamic barrier. Consequently, the FeN₂O₂ SAC achieves a 4-CP conversion of 94.8% and a p-BQ yield of 62.6%, outperforming the FeN₄ architecture. This system demonstrates long-term durability in flow electrolyzers alongside a reduced carbon footprint. By coupling pulsed electrocatalysis with dynamic coordination chemistry, this work establishes a paradigm for "pollutant-to-product" conversion, offering a scalable blueprint for circular chemical economies.