Abstract
Electrochemistry can provide an efficient and sustainable way to treat environmental waters polluted by chlorinated organic compounds. However, the electrochemical valorization of 1,2-dichloroethane (DCA) is currently challenged by the lack of a catalyst that can selectively convert DCA in aqueous solutions into ethylene. Here we report a catalyst comprising cobalt phthalocyanine molecules assembled on multiwalled carbon nanotubes that can electrochemically decompose aqueous DCA with high current and energy efficiencies. Ethylene is produced at high rates with unprecedented ~100% Faradaic efficiency across wide electrode potential and reactant concentration ranges. Kinetic studies and density functional theory calculations reveal that the rate-determining step is the first C–Cl bond breaking, which does not involve protons—a key mechanistic feature that enables cobalt phthalocyanine/carbon nanotube to efficiently catalyse DCA dechlorination and suppress the hydrogen evolution reaction. The nanotubular structure of the catalyst enables us to shape it into a flow-through electrified membrane, which we have used to demonstrate >95% DCA removal from simulated water samples with environmentally relevant DCA and electrolyte concentrations.
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Data availability
The atomic coordinates of the optimized structures (at neutral charge) for DFT calculations are provided in Supplementary Data 1. The measurement data presented within this paper and other findings of this study are available from the corresponding authors upon reasonable request.
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Acknowledgements
This work (materials synthesis, structural characterization and catalysis work) was primarily supported as part of the Center for Hybrid Approaches in Solar Energy to Liquid Fuels (CHASE), an Energy Innovation Hub funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, under award no. DE-SC0021173 (H.W.). Computational work was supported by the Liquid Sunlight Alliance, which is supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight Hub under award no. DE-SC0021266 (W.A.G.) and an individual fellowship from the Resnick Sustainability Institute at Caltech (S.K.), and used the Extreme Science and Engineering Discovery Environment (XSEDE) for DFT calculations, which is supported by National Science Foundation grant no. ACI-1548562 (W.A.G.). Electrified membrane filtration work was supported by the NSF Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment (EEC-1449500; M.E.). STEM and EDX characterizations were supported by the NSF career award no. 1749742 (J.J.C.). We thank J. Lee and J. D. Fortner (Department of Chemical and Environmental Engineering, Yale University) for providing graphene oxide.
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C.C. and H.W. conceived and designed the project. C.C. and C.L.R. prepared the CoPc/CNT. C.C. conducted the electrocatalytic DCA dechlorination. X.W. conducted the flow-through DCA dechlorination with supervision from M.E. S.K. carried out the DFT calculations with supervision from W.A.G. J.L.H. and Q.P.S. performed the TEM imaging with supervision from J.J.C. N.J.H. performed the ICP-MS measurements. C.C. and H.W. wrote the manuscript with input from X.W. and S.K. H.W. supervised the project. All the authors discussed the results and commented on the manuscript.
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Supplementary Figs. 1–25 and Tables 1 and 2.
Supplementary Data 1
Coordinates of the optimized structures (at neutral charge) in this Article.
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Choi, C., Wang, X., Kwon, S. et al. Efficient electrocatalytic valorization of chlorinated organic water pollutant to ethylene. Nat. Nanotechnol. 18, 160–167 (2023). https://doi.org/10.1038/s41565-022-01277-z
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DOI: https://doi.org/10.1038/s41565-022-01277-z