AbstractThe authors report on a chromogenic system based MnO2 nanosheet and the chomgenic substrate 3,3′,5,5′-tetramethylbenzidine (TMB). The MnO2 nanosheet can oxidize TMB in acidic environment to form a yellow solution with an absorption peak at 450 nm. The process does not require the presence of an enzyme or H2O2. However, on addition of ferrous ion to the chromogenic system, the MnO2 nanosheet is decomposed via the redox reaction that occurs between Fe(II) and MnO2. As a result, the intensity of the absorption at 450 nm is reduced. This finding is exploited in a photometric method for determination of Fe(II) that shows high selectivity and a 0.3 μM detection limit (based on the 3σ/slope criterion). Fe(II) can also be detected visually in concentrations down to 100 μM. The method was applied to the determination of Fe(II) in spiked water samples and gave satisfactory recoveries. Graphical abstractSchematic illustration of the chromogenic system composed of MnO2 nanosheets and 3,3′,5,5′-tetramethylbenzidine (TMB) for highly sensitive colorimetric detection of ferrous ion (Fe2+)

中文翻译：

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超薄二维 MnO2 纳米片作为 3,3',5,5'-四甲基联苯胺显色底物的稳定共反应物，用于铁（II）离子的视觉和比色检测

摘要作者报道了基于 MnO2 纳米片和同质底物 3,3',5,5'-四甲基联苯胺 (TMB) 的显色系统。MnO2 纳米片可以在酸性环境中氧化 TMB，形成黄色溶液，在 450 nm 处有吸收峰。该过程不需要酶或 H2O2 的存在。然而，在显色系统中加入亚铁离子后，MnO2 纳米片会通过 Fe(II) 和 MnO2 之间发生的氧化还原反应分解。结果，450 nm 处的吸收强度降低。这一发现被用于测定 Fe(II) 的光度方法中，该方法显示出高选择性和 0.3 μM 检测限（基于 3σ/斜率标准）。Fe(II) 也可以在低至 100 μM 的浓度下进行视觉检测。该方法用于测定加标水样品中的 Fe(II) 并获得了令人满意的回收率。由二氧化锰纳米片和 3,3',5,5'-四甲基联苯胺 (TMB) 组成的显色系统示意图，用于亚铁离子 (Fe2+) 的高灵敏度比色检测