Electrocatalytic Dechlorination of Dichloromethane in Water Using a Heterogenized Molecular Copper Complex

Abstract

The remediation of organohalides from water is a challenging process in environment protection and water treatment. Herein, we report a molecular copper(I) complex with two triazole units, CuT2, in a heterogeneous aqueous system that is capable of dechlorinating dichloromethane (CH 2 Cl 2 ) to afford hydrocarbons (methane, ethane, and ethylene). The catalytic performance is evaluated in water and presented high Faradaic efficiency (average 70% CH 4 ) across a range of potentials (−1.1 to −1.6 V vs Ag/AgCl) and high activity (maximum −25.1 mA/cm 2 at −1.6 V vs Ag/AgCl) with a turnover number of 2.0 × 10 7 . The CuT2 catalyst also showed excellent stability for 14 h of constant exposure to CH 2 Cl 2 and 10 h of CH 2 Cl 2 exposure cycling. The control compound, a copper-free triazole unit (T1), was also investigated under the same condition and showed inferior catalytic activity, indicating the importance of the copper center. Plausible catalytic mechanisms are proposed for the formation of C 1 and C 2 products via radical intermediates. Computational studies provided additional insight into the reaction mechanism and the selectivity toward the CH 4 formation. The findings in this study demonstrate that complex CuT2 is an efficient and stable catalyst for the dehalogenation of CH 2 Cl 2 and could potentially be used for the exploration of the removal of halogenated species from aqueous systems.

Electrocatalytic Hydrogen Evolution Using A Molecular Antimony Complex under Aqueous Conditions: An Experimental and Computational Study on Main‐Group Element Catalysis

“…Computational Details : Theoretical calculations were performed by following a similar approach as in our previous study [43] . We utilized the Orca 5.0 software package [47] with the B3LYP density functional [48] .…”

“…DFT calculations were performed to elucidate which of these possible reaction mechanisms is more probable for the HER on the SbSalen complex. We have followed a computational procedure similar to our previous work on the electrocatalytic dechlorination of dichloromethane [43] . The proposed reaction mechanism is shown in Figure 4A and its corresponding reaction profile in Figure 4B.…”

“…We have followed a computational procedure similar to our previous work on the electrocatalytic dechlorination of dichloromethane. [43] The proposed reaction mechanism is shown in Figure 4A and its corresponding reaction profile in Figure 4B. A detailed plot with the energy levels of all feasible reaction intermediates is provided in the Supporting Information (Figure S12).…”

“…Computational Details: Theoretical calculations were performed by following a similar approach as in our previous study. [43] We utilized the Orca 5.0 software package [47] with the B3LYP density functional. [48] All structures were optimized using an unrestricted wave function and the def2-TZVPP for Sb and def2-TZVP basis set for all other atoms.…”

Water Purification of Classical and Emerging Organic Pollutants: An Extensive Review

“…Williams et al [54] tested the feasibility of the dechlorination of DCM through an electrocatalytic process by using a molecular copper(I) complex with two triazole units (CuT 2 ). The formation of by-products was monitored to evaluate the removal of the pollutant; in particular, a Faradaic efficiency of 70% for methane was measured.…”