Wei Shengnan, Xiao Danlin, Bian Chao, Li Yang
State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100190, China.
School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
ACS Omega. 2024 Apr 25;9(18):20293-20303. doi: 10.1021/acsomega.4c00717. eCollection 2024 May 7.
Phosphorus and nitrogen are important elements in both environmental cycles and biological growth, and their imbalance can lead to serious environmental and biological problems. It is important to be able to monitor the concentration of nitrate and phosphate in the water online. In this paper, a bifunctional boron-doped diamond (BDD) electrode with repeatable electrochemical renewal and modification ability has been developed and used as a shared working electrode for the determination of nitrate and phosphate. First, phosphate can be detected directly with a bare BDD electrode. After a thin copper (Cu) layer was electrodeposited on the BDD electrode, nitrate could be determined. The copper layer is then removed under a positive voltage, and the BDD electrode is renewed and can be used again for phosphate detection. This method enables the detection of both phosphate and nitrate while also improving the stability and repeatability through the renewal of the electrode surface. The segmented linear ranges for phosphate were 0.02-0.4 and 0.4-3 mg/L with a detection limit of 0.004 mg/L. The sensor detected nitrate in a wide concentration range, with segmented linear relationships in the ranges of 0.07-3 and 3-100 mg/L, with a detection limit of 0.065 mg/L. The electrochemical sensor based on the BDD electrode has a good reproducibility for phosphate and nitrate detection. The relative standard deviation (RSD) values of the current responses were 2.98, 2.79, 1.66, 1.81, and 1.23%, respectively, for 35 consecutive tests in 0.05, 0.2, 0.5, 1, and 1.5 mg/L phosphate solution. The RSD values of the current responses were 2.00, 0.97, and 1.03%, respectively, for 25 consecutive tests in 5, 7, and 10 mg/L nitrate solution.
磷和氮是环境循环和生物生长中的重要元素，它们的失衡会导致严重的环境和生物问题。能够在线监测水中硝酸盐和磷酸盐的浓度非常重要。本文开发了一种具有可重复电化学更新和修饰能力的双功能硼掺杂金刚石（BDD）电极，并将其用作测定硝酸盐和磷酸盐的共享工作电极。首先，裸BDD电极可直接检测磷酸盐。在BDD电极上电沉积一层薄铜（Cu）后，可测定硝酸盐。然后在正电压下除去铜层，BDD电极得以更新，可再次用于磷酸盐检测。该方法能够同时检测磷酸盐和硝酸盐，还通过更新电极表面提高了稳定性和可重复性。磷酸盐的分段线性范围为0.02 - 0.4和0.4 - 3 mg/L，检测限为0.004 mg/L。该传感器在很宽的浓度范围内检测硝酸盐，在0.07 - 3和3 - 100 mg/L范围内呈分段线性关系，检测限为0.065 mg/L。基于BDD电极的电化学传感器对磷酸盐和硝酸盐检测具有良好的重现性。在0.05、0.2、0.5、1和1.5 mg/L磷酸盐溶液中连续35次测试，电流响应的相对标准偏差（RSD）值分别为2.98%、2.79%、1.66%、1.81%和1.23%。在5、7和10 mg/L硝酸盐溶液中连续25次测试，电流响应的RSD值分别为2.00%、0.97%和1.03%。
