Electro-pulsation-generated variable-valent metal triggers alternate pesticide oxidation-chlorinated byproduct reduction on ruthenium-single-atom electrode.

Abstract

Anodic oxidation presents a compelling strategy for pesticide-contained wastewater treatment. However, due to the reactive chlorine species-induced side reactions, toxic chlorinated byproducts are prevalent. Herein, a MOF derivative Ru-single-atom electrode, Ru-SbO_X, was specialized for use in electro-pulsation to realize pesticide degradation and in-situ byproduct elimination. The introduction of single-atomic Ru promoted pseudocapacitive Ruⁿ⁺-Sbⁿ⁺ redox conversion, electro-creating metastable high-valent Sb⁵⁺ and low-valent Sb³⁺, then triggering the •OH and •H generation during anodic and cathodic cycles, respectively. This beneficially created an alternating oxidation-reduction environment in an identical electrode, leading to alternate pesticide degradation-byproduct elimination. These allowed Ru-SbO_X to achieve a super-prominent normalized phoxim degradation kinetics constant (3.1 × 10^-6 m·s^-1) in anodic cycles, surpassing other state-of-the-art electrodes; meanwhile, the reactive chlorine species-induced chlorinated byproducts and even N, S, P-related byproducts were in-situ eliminated by at least 10 times in cathodic cycles. This work provides a new perspective for tuning the valence-variable metal in the single-atom electrode to achieve efficient pesticide degradation and in-situ byproduct elimination using the electro-pulsation method.