Efficient full dechlorination of chlorinated ethenes on single enzyme-like Co−N₄ sites in nitrogen-doped carbons

Chlorinated ethenes are ubiquitous contaminants in groundwater. Here, by embedment of enzyme-like Co−N₄ sites in the nitrogen-doped carbon support, we prepared a Co−NC catalyst to combine the advantages of abiotic and biological dechlorination strategies. Co−NC exhibited superior reactivity and stability for catalytic dechlorination of chlorinated ethenes under various conditions. Up to 94.8% of trichloroethene could be transformed directly to acetylene without toxic intermediates. Moreover, Co−NC could utilize electrons from dissolved Fe(II), which is low-cost and a common component in the groundwater, making the Co−NC-based strategies sustainable for the remediation. Even with such a weak reductant, acetylene was still the dominant product. Those catalytic properties originate from the synergism of the nitrogen-doped carbons and the highly active Co sites. This synergism favors a mechanism where the toxic intermediates are bound on Co sites until the full dechlorination, due to the excellent electron-storage ability and the electronic delocalization characteristic of nitrogen-doped carbons.