Two CuO nanostructures, namely, nanospheres (CuONSs) and nanochains (CuONCs) with different shapes but similar diameters, were synthesized and characterized. With these two nanomaterials as electrode modifiers, a systematic comparative study was conducted to examine their electrochemical sensing of catechol (CT) using a dual-working electrode system. The results suggest that for CuONS- and CuONC-modified glassy carbon electrodes, the electrode process for the CT redox is diffusion-controlled, and the modification amount and electrolyte pH have a similar effect on the response. However, the CuONCs showed a higher peak current and lower peak potential, as well as a lower detection limit for the electrochemical oxidation of CT. This is explained by the lower charge transfer impedance and higher electroactive surface area of the CuONCs. Notably, an unexpected peak appeared in the cyclic voltammograms when the pH was <4 for the CuONCs and <3 for the CuONSs. For this phenomenon, UV-Vis spectra, zeta potential, and size distribution experiments demonstrated changes in the two CuO nanostructures at lower pH, illustrating that CuONSs can tolerate a higher pH as compared to CuONCs. The multiple comparisons between the two nanomaterials presented here can provide references for the selection of electrochemical sensing materials.

中文翻译：

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两种CuO纳米材料修饰双工作电极的电化学传感性能

合成并表征了两种形状不同但直径相似的 CuO 纳米结构，即纳米球（CuONS）和纳米链（CuONC）。以这两种纳米材料作为电极改性剂，进行了系统的比较研究，以使用双工作电极系统检查它们对儿茶酚（CT）的电化学传感。结果表明，对于 CuONS 和 CuONC 修饰的玻碳电极，CT 氧化还原的电极过程是扩散控制的，并且修饰量和电解质 pH 对响应有类似的影响。然而，CuONCs 显示出较高的峰值电流和较低的峰值电位，以及 CT 电化学氧化的较低检测限。这是因为 CuONC 具有较低的电荷转移阻抗和较高的电活性表面积。值得注意的是，当 CuONC 的 pH 值 < 4 和 CuONS 的 pH 值 < 3 时，循环伏安图中出现了意外的峰。对于这种现象，紫外-可见光谱、zeta 电位和尺寸分布实验证明了两种 CuO 纳米结构在较低 pH 下的变化，表明与 CuONC 相比，CuONS 可以耐受更高的 pH 值。本文提出的两种纳米材料的多重比较可为电化学传感材料的选择提供参考。