Atomic Hydrogen in Hydrogenolysis: Converting and Detoxifying Carbon-Heteroatom Bonds via Paired Electrolysis

The presence of carbon-heteroatom bonds (C-N, C-O, and C-S) significantly enhances the stability and toxicity of pollutants. Hydroxyl radicals (^•OH)-mediated electrochemical processes show promise; however, the bond energies associated with carbon-heteroatom bonds exceed 200 kJ/mol, which constrains the effectiveness of oxidative degradation and detoxification. We have developed a paired electrolysis process coupling hydrogen atom (H^*) generation at the cathode with ^•OH production at the anode. The involvement of H^* and ^•OH in this system was first confirmed by using methylene blue (MB) as an electrochemical probe. When applied to the degradation of glyphosate (GP), which contains C-N bonds, the paired electrolysis process achieved removal efficiencies for COD, TOC, and toxicity that were twice those of individual oxidation processes. The degradation kinetics also exhibited performance that was double that of individual oxidation processes. Mass spectrometry and theoretical calculations confirmed that hydrogenolysis of H^* effectively attacks high-energy C-N bonds, thereby circumventing the rate-limiting steps associated with standalone ^•OH oxidation, enhancing pollutant degradation and reducing toxicity. When applied to pollutants containing C-O and C-S bonds, the paired electrolysis process demonstrated improvements in COD, TOC, and toxicity removal of approximately 30%, 10%, and 20%, respectively, showcasing its multifunctionality and scalability. Seven days of practical wastewater experiments further validated the effectiveness and durability of this technology.