Reduced graphene oxide/metal oxide (rGO/MO) hybrid has been widely used as a catalyst, while dissolved oxygen or radicals are generally recognized as the oxidant. This study finds that the adsorbed arsenite (As(III)) on rGO/MO is oxidized to arsenate (As(V)) in the absence of other oxidants or radicals. The oxidation of As(III) is observed on varying rGO/MOs, including rGO/MOs composited of different types of reduced graphene oxide (rGO) and metal oxide. The epoxy group on rGO acts as the oxidant, evidenced by the significant correlation between the consumption of epoxy group and oxidation of As(III). Meanwhile, metal oxide provides adsorption sites for As(III) during the adsorption–oxidation process. Based on a combination of spectroscopic measurements and computational calculation, a possible pathway for As(III) oxidation by rGO/MO is proposed: the oxygen atom in the epoxy group is bonded to the adsorbed As^IIIO₃, which is consequently oxidized to As^VO₄. Overall, this study proves the role of rGO/MO as an oxidant, which opens a new perspective on future studies using rGO/MO as a catalyst for the oxidation reaction.

中文翻译：

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还原氧化石墨烯/金属氧化物复合材料上环氧基氧化亚砷酸盐

还原氧化石墨烯/金属氧化物（rGO/MO）杂化物已被广泛用作催化剂，而溶解氧或自由基通常被认为是氧化剂。这项研究发现，在没有其他氧化剂或自由基的情况下，rGO/MO 上吸附的亚砷酸盐 (As(III)) 会被氧化为砷酸盐 (As(V))。在不同的 rGO/MO 上观察到 As(III) 的氧化，包括由不同类型的还原氧化石墨烯 (rGO) 和金属氧化物复合而成的 rGO/MO。rGO 上的环氧基团充当氧化剂，环氧基团的消耗与 As(III) 的氧化之间的显着相关性证明了这一点。同时，金属氧化物在吸附氧化过程中为As(III)提供吸附位点。基于光谱测量和计算计算的结合，提出了rGO/MO氧化As(III)的可能途径：环氧基中的氧原子与吸附的As ^III O ₃键合，从而被氧化为As^氧分压₄．_ 总的来说，这项研究证明了rGO/MO作为氧化剂的作用，为未来使用rGO/MO作为氧化反应催化剂的研究开辟了新的视角。