Mutual interference issues between heavy metal ions tremendously affect the detection reliability and accuracy in water quality analysis, especially the serious interference of Cu(II) on the detection of As(III) is greatly hard to overcome, which needs to be solved urgently. Herein, iron single-atom catalysts with different coordination structures of FeN₂C₂ and FeN₃P are constructed to selectively catalyze the detection of As(III) in the coexistence of Cu(II). FeN₃P achieves a high sensitivity of 3.90 µA ppb^-1 toward As(III) in NH₄Cl/NH₃·H₂O electrolyte (pH 8.0), completely avoiding Cu(II)-interference. Moreover, the turnover frequency (TOF) of FeN₃P is an order of magnitude higher than that of FeN₂C₂. X-ray absorption fine structure (XAFS) spectroscopy and density functional theory (DFT) calculations demonstrate that an As-O bond of H₃AsO₃ is broken by the strong affinities between both P and O atoms and Fe and As atoms, and H₃AsO₃ are preferentially reduced by FeN₃P during adsorptive process. Meanwhile, the low reaction energy barrier of the rate-determined step for As(III) reduction over FeN₃P also accelerates the deposition of As(III) and enhances its response signals. The free-Cu(II) are difficult to adsorb on FeN₃P and do not compete with As(III) for Fe active sites, which contributes to the excellent anti-Cu(II) interference capability.

重金属离子之间的相互干扰问题极大地影响了水质分析中检测的可靠性和准确性，尤其是Cu(II)对As(III)检测的严重干扰难以克服，亟待解决。_{在此，本文构建了具有不同配位结构的FeN 2} C ₂和FeN ₃ P 的铁单原子催化剂，以选择性催化Cu(II)共存中As(III)的检测。FeN _{3 P 对 NH 4} Cl/NH ₃ ·H ₂中的 As(III)具有 3.90  µA ppb ^{-1的高灵敏度}O 电解质（pH 8.0），完全避免 Cu(II) 干扰。此外，FeN ₃ P 的转换频率(TOF) 比FeN ₂ C ₂高一个数量级。X 射线吸收精细结构 (XAFS) 光谱和密度泛函理论 (DFT) 计算表明，H ₃ AsO ₃的 As-O 键因P 和 O 原子与 Fe 和 As 原子之间的强亲和力而断裂，而 H ₃ AsO ₃在吸附过程中优先被FeN ₃ P还原。_{同时，FeN 3}上 As(III) 还原的速率决定步骤的低反应能垒P 还加速 As(III) 的沉积并增强其响应信号。游离Cu(II)难以吸附在FeN ₃ P上，不与As(III)竞争Fe活性位点，具有优异的抗Cu(II)干扰能力。