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Electric charges recovering from aqueous media using conductor oxides

Abstract : Nowadays, it’s commonly admitted that n- type conductor oxides (≡ MOx) with large bandgap, as SnO2:F, can generate hydroxyl radicals from wa ter, according to the reaction below [1]: MOx + H2O → MOx(•OH ) + H+ + 1 e–(1)In electrocatalytic conditions, in the field of waste water treatment for example, this behav ior at metal oxides was studied by numerous au-thors [2,3]. However, the mechanism of hy-droxyl radical generation on the oxide surfaces was not studied in details. Unfortunately no mention exists in literature on the opportunity to recover the elementary electric charges de rived from the hydroxyl radical generation process. It’s important to underline the effect of com-plementary charge generation by the surfaces of conductor oxide anodes was already outlined by the previous research works [4]. Despite some recent contributions demonstrat-ing the existence of an oxide layer on the noble metal surfaces [5 ], the last are not able to form hydroxyl radicals in aqueous media contrary to the semi-conductor metal oxides. In our study we propose a detailed reaction cycle for the hy-droxyl radical general by a conductor oxide sur-face (Figure 1). The proposal approach allows to consider that the radical formation occurs before the water splitting (≡ water electrolysis). The key steps of this mechanism, underlined by brown circle s on Figure 1, were verified with independente methods. The hydroxyl radical formation on the SnO2:F surface was tested di-rect ly by the oxidation reaction Pb2+ → PbO2that doesn’t occur at the metal surfaces, and un-directly by the oxidation reaction C6H6O2 → C6H4O2. Futhermore, benefits of organic com-pounds (Hydroxyl radical scavengers, HRS) in the water for the recovering of electric charges was highlighted. To conclude, according with this new reaction schema between water and anoxide surface, the recovering at elementary elec-tric charges becomes available.
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https://hal.mines-ales.fr/hal-03100649
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Submitted on : Wednesday, January 6, 2021 - 5:12:37 PM
Last modification on : Friday, January 8, 2021 - 3:07:00 AM

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  • HAL Id : hal-03100649, version 1

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Valentin Ledoux, Alexei Evstratov. Electric charges recovering from aqueous media using conductor oxides. SMS 2019 / EGF2019 / NanoMed 2019 Joint Conferences, Oct 2019, Lisbonne, Portugal. ⟨hal-03100649⟩

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