Fe-based metal oxide nanomaterials have attracted significant attention as the electroanalytical sensing for heavy metal ions (HMIs) detection. It is recently found that their activities should be mainly ascribed to their valance change behavior (i.e. the Fe²⁺/Fe³⁺ cycle). However, how to promote the Fe²⁺/Fe³⁺ cycle to further increase their detection performance is highly desired yet challenging. Herein, the nanocomposite of Fe₃O₄/MoS₂ is developed as a sensing for the electrochemical detection of the highly toxic As(III). Through a series of characterizations including the XPS and DFT, the Fe₃O₄/MoS₂ shows an accelerated electron transfer induced by the valence change of Fe²⁺/Fe³⁺ cycle. The active Mo⁴⁺ on MoS₂ can serve as electron doner to reduce the Fe³⁺ to Fe²⁺ on Fe₃O₄, and thus promotes the Fe²⁺/Fe³⁺ cycle. Moreover, the synergistic effect between the excellent adsorption ability of Fe₃O₄ towards As(III) and the good conductivity of MoS₂ will further benefit to the detection. As expected, the Fe₃O₄/MoS₂ reflects an outstanding detection performance to As(III) with a sensitivity of 4.16 μA•ppb^–1, which even much outperforms than that of noble-metal materials. Overall, these discoveries are expected to drive great advances in the application of the accelerated valence change behavior for electroanalysis.

Fe基金属氧化物纳米材料作为重金属离子（HMIs）检测的电分析传感引起了广泛关注。最近发现它们的活动应该主要归因于它们的价态变化行为（即Fe ²⁺ /Fe ³⁺循环）。然而，如何促进Fe ²⁺ /Fe ³⁺循环以进一步提高其检测性能是非常需要但具有挑战性的。在此，Fe ₃ O ₄ /MoS ₂的纳米复合材料被开发用于电化学检测剧毒 As(III) 的传感。通过包括 XPS 和 DFT 在内的一系列表征，Fe ₃ O₄ /MoS _{2显示了由Fe} ²⁺ /Fe ³⁺循环的价态变化引起的加速电子转移。MoS ₂上的活性Mo ⁴⁺可以作为电子给体将Fe ³⁺还原为Fe ₃ O ₄上的Fe ²⁺，从而促进Fe ²⁺ /Fe ³⁺循环。_{此外，Fe 3} O ₄对As(III)的优异吸附能力与MoS ₂良好的导电性之间的协同效应将进一步有利于检测。正如所料，Fe ₃ O ₄/MoS ₂反映了对As(III)的出色检测性能，灵敏度为4.16 μA•ppb ^–1，甚至远远优于贵金属材料。总体而言，这些发现有望推动加速价变化行为在电分析中的应用取得巨大进展。