Hydrodehalogenation of Polychloromethanes on Silver‐Based Gas Diffusion Electrodes

Rod-Like Nanostructured Cu-Co Spinel with Rich Oxygen Vacancies for Efficient Electrocatalytic Dechlorination

Dichloromethane (CH₂Cl₂) hydrodechlorination to methane (CH₄) is a promising approach to remove the halogenated contaminants and generate clean energy. In this work, rod-like nanostructured CuCo₂O₄ spinels with rich oxygen vacancies are designed for highly efficient electrochemical reduction dechlorination of dichloromethane. Microscopy characterizations revealed that the special rod-like nanostructure and rich oxygen vacancies can efficiently enhance surface area, electronic/ionic transport, and expose more active sites. The experimental tests demonstrated that CuCo₂O₄-3 with rod-like nanostructures outperformed other morphology of CuCo₂O₄ spinel nanostructures in catalytic activity and product selectivity. The highest methane production of 148.84 μmol in 4 h with a Faradaic efficiency of 21.61% at -2.94 V (vs SCE) is shown. Furthermore, the density function theory proved oxygen vacancies significantly decreased the energy barrier to promote the catalyst in the reaction and O_v-Cu was the main active site in dichloromethane hydrodechlorination. This work explores a promising way to synthesize the highly efficient electrocatalysts, which may be an effective catalyst for dichloromethane hydrodechlorination to methane.

Semi-solid electrolyte with layered heterometallic low-valent electron-mediator enabling indirect destruction of gaseous toluene

The electrochemical degradation of air pollutants, particularly volatile organic compounds (VOCs), at their gaseous state is a promising method. However, it remains at an infant stage due to sluggish solid-gas electron transfers at room temperature. We established a triphase reaction condition using a semi-solid electrolyte layer between the electrode and membrane to enhance the electron transfer at room temperature. A polyvinyl alcohol (PVA) gel layer was inserted between a bimetallic layered CuNi(CN)₄ complex coated Cu foam electrode (TCNi-Cu) and Nafion 324 membrane for the degradation of gaseous toluene. The cyclic voltammetry of TCNi-Cu using a sodium hydroxide-coated copper mesh electrode at a triphase showed Cu¹⁺ and Ni¹⁺ stabilization at -0.7 and -0.9 V, respectively, which was similar to the liquid phase electron transfer behavior. The degradation capacity of gaseous toluene without using electrogenerated TCNi-Cu + PVA gel was 0.54 mg cm² min^-1, whereas that of TCNi-Cu + PVA gel layers was 1.17 mg cm^-2min^-1, which revealed the mediation effect at a triphase condition. Toluene was converted into oxygen-containing products, such as butanol, propanol, and acetone (without reduction products), which revealed that indirect oxidation occurred at the cathode using an in-situ generated oxidant, such as OH˙ radical. As an electron-mediator, Cu¹⁺ was used to form oxidants for the degradation of toluene at -0.7 V. The toluene removal rate reached 1.4 μmol h^-1, with an energy efficiency of 0.15 Wh L^-1. This study is the first attempt to describe a liquid-electrolyte-free cathodic half-cell in electrochemical application to VOCs degradation, highlighting the electron transfer at room temperature.