电接枝聚乙烯亚胺改性碳纤维电极电化学性能及其电场响应研究

碳纤维电极表面氨基改性可以显著提高其电化学性能和电场响应性能。通过高温氧化和电化学接枝相结合的方法，在碳纤维表面接枝不同分子量（0.6K、1.8K、10K）聚乙烯亚胺分子来调控电极/海水界面双电层结构。实验发现，长分子链之间因氢键更强的相互作用更容易穿插交叠，形成稳定双电层结构。结果表明：PEI-10K的性能最佳，其比电容达到12.8 F·g^-1，电荷转移电阻和低频容抗显著降低；配对电极的电位漂移量仅为0.05 mV/d，电极自噪声降为2.61 nV/sqrt(Hz)，并且可以响应1 mHz、0.03 mV/m的低频弱电场信号；改性后碳纤维电极的响应灵敏度、准确度得到了显著提高，可用于制备高性能海洋电场传感器，提高水下电场探测能力。

Electrochemical Properties and Electric Field Response of Electrically Grafted Polyethyleneimine Modified Carbon FiberElectrodes

The electrochemical and electric field response properties of carbon fiber electrodes can be significantly enhanced through surface amine modification. In this paper, polyethyleneimine (PEI) of different molecular weights (0.6K，1.8K，10K) is grafted on the surface of carbon fibers by a combination of high-temperature oxidation with electrochemical grafting to modulate the bilayer structure at the electrode/seawater interface. It is found that longer molecular chains are more easily interspersed and overlapped for they have stronger hydrogen bonding interactions, resulting in a more stable electric bilayer structure. Therefore, PEI-10K shows the best performance with a specific capacitance of 12.8 F·g^-1 and charge transfer resistance and low-frequency capacitive reactance significantly reduced. The potential drift of the paired electrode is only 0.05 mV/d. The self-noise of the electrode is reduced to 2.61 nV/sqrt (Hz) and can respond to the low-frequency weak electric field signal of 1 mHz and 0.03 mV/m. The response sensitivity and accuracy of the modified carbon fiber electrode have been significantly improved. This approach can be used to prepare high-performance marine electric field sensor and improve the detection ability of underwater electric field.