Differential pulse anodic stripping voltammetry (DPASV) is one of the widely used methods for measuring heavy metal ions (HMIs). However, the severe memory effects caused by the incomplete oxidation of zero-valent metals during the dissolution process lead to undesirable results of sensitivity and repeatability. To solve this problem, a photo-assisted electrochemical sensor based on bismuth molybdate/biochar (BMOC) electrode is proposed for Hg(II) detection. During the electrodeposition via the DPASV method, the massive electrons are generated by photoexcitation and the abundant active sites of BMOC contribute to the high accumulation of Hg(0), which can be thoroughly oxidized under the applied electrode potential. The synergistic effect caused by superoxide radicals and hydroxyl radicals generated during BMOC-assisted photocatalysis, greatly enhances the signal of the dissolution current and effectively eliminates the memory effect. The BMOC electrode benefits from these photoelectric properties and shows excellent measurement performance for Hg(II) over a wide range with a low detection limit of up to 3 × 10^-5 µg·mL⁻¹. Furthermore, the BMOC electrode exhibits a photoreduction efficiency of 99.99% for Cr(VI) (10 µg·mL⁻¹) within 30 min under the visible light irradiation. The present study provides a viable photo-assisted sensing platform for efficient determination and reduction of HMIs.

差分脉冲阳极溶出伏安法 (DPASV) 是广泛使用的重金属离子 (HMI) 测量方法之一。然而，零价不完全氧化引起的严重记忆效应 溶解过程中的金属会导致不希望出现的灵敏度和可重复性结果。为了解决这个问题，提出了一种基于钼酸铋/生物炭 (BMOC) 电极的光辅助电化学传感器用于 Hg(II) 检测。在通过 DPASV 方法进行电沉积过程中，大量电子由光激发产生，BMOC 丰富的活性位点有助于 Hg(0) 的高积累，在施加的电极电位下可以被彻底氧化。BMOC辅助光催化过程中产生的超氧自由基和羟基自由基的协同作用，大大增强了溶解电流的信号，有效消除了记忆效应。^-5微克·毫升^-1。此外，BMOC 电极在可见光照射下 30 分钟内对 Cr(VI) (10 µg·mL ^{-1 ) 的光还原效率为 99.99%。}本研究为有效确定和减少 HMI 提供了一个可行的光辅助传感平台。