Electrochemical dechlorination and hydrocarbon valorization by cobalt phthalocyanine with non-proton-coupled redox property.

Abstract

Electrochemical dechlorination provides a sustainable method to treat chlorinated volatile organic compounds polluted water with producing value-added hydrocarbon. However, dechlorination of dichloromethane (CH₂Cl₂) generates *CH₃ and *CH₂Cl intermediates, which are highly unstable due to lack of efficient hyperconjugation from neighboring carbon sites. Herein, we report that cobalt phthalocyanine (CoPc) grafts onto sulfur-doped graphene toward efficient electrocatalysis of CH₂Cl₂ dechlorination at moderate potentials. It reveals that sulfoxide groups within graphene linked to Co sites by an axial coordination, resulting in an electron donation effect to decrease the barriers of elemental dechlorination step. While in situ electrochemically generates [Co¹⁺Pc]⁻ species mediated the electron transfer from Co sites to CH₂Cl₂. The production rate of CH₄ is significantly enhanced compares to the current level, and an additional case of producing C₂H₄ and C₂H₆ is achieved. For potential practical application, the electrochemical dechlorination of a diluted CH₂Cl₂ solution is validated in an electrofiltration module setup by an efficient flow-through mode.