Oxygen vacancy based WO3/SnO2-x promote electrochemical H2O2 accumulation by two-electron water oxidation reaction and toxic uniform dimethylhydrazine degradation

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The key to constructing an anodic electro-Fenton system hinges on two pivotal criteria: enhancing the catalyst activity and selectivity in water oxidation reaction (WOR), while simultaneously inhibiting the decomposition of hydrogen peroxide (H 2 O 2 ) which is on-site electrosynthesized at the anode. To address the issues, we synthesized novel WO 3 /SnO 2-x electrocatalysts , enriched with oxygen vacancies , capitalize on the combined activity and selectivity advantages of both WO 3 and SnO 2-x for the two-electron pathway electrocatalytic production of H 2 O 2 . Moreover, the introduction of oxygen vacancies plays a critical role in impeding the decomposition of H 2 O 2 . This innovative design ensures that the Faraday efficiency and yield of H 2 O 2 are maintained at over 80 %, with a noteworthy production rate of 0.2 mmol h −1 cm −2 . We constructed a novel electro-Fenton system that operates using only H 2 O as its feedstock and applied it to treat highly toxic uniform dimethylhydrazine (UDMH) from rocket launch effluent. Our experiments revealed a substantial total organic carbon (TOC) removal, achieving approximately 90 % after 120 mins of treatment. Additionally, the toxicity of N -nitrosodimethylamine (NDMA), a byproduct of great concern, was shown to be effectively mitigated, as evidenced by acute toxicity evaluations using zebrafish embryos. The degradation mechanism of UDMH is predominantly characterized by the advanced oxidative action of H 2 O 2 and hydroxyl radicals , as well as by complex electron transfer processes that warrant further investigation.