【摘要】 研究了以铂丝为基体的电位型聚吡咯(PPy)pH传感器。在0. 1mol/L吡咯单体和0 1mol/L吡咯单体+0 .1mol/L磷酸氢钠水溶液中利用电化学方法制备了PPy膜,并用红外光谱表征未掺杂(Pt/PPy)和掺杂碳酸氢根聚吡咯膜(Pt/PPy(HCO-3 ) )的结构,并探讨了聚吡咯膜的电化学阻抗谱特征。Pt/PPy在酸性(pH=4 01)、中性(pH=6 .85)、碱性(pH=9 14)溶液中的高频和中频区包含2个半圆,低频区表现为半无限扩散Warburg型阻抗(Zw),对应H+从溶液相向电极表面的扩散过程。Pt/PPy(HCO-3 )在相应的溶液中电荷转移电阻和膜电阻显著增大,交流阻抗图谱在相应的pH缓冲溶液中包含2个半圆,而在低频区没出现半无限扩散Wanburg阻抗特征。Pt/PPy表现出良好的电位特性(pH值在3~10范围内,其能斯特斜率为49 32mV/pH),良好的线性(r=-0 .997 1),以及较短的响应时间,并且对常规阳离子(K+、Na+ )有较小的选择性系数。更多还原

【Abstract】 A pH sensor was fabricated from polypyrrole（PPy） on Pt wire. PPy was prepared electrochemically in a 0.1 mol/L Py aqueous solution with or without addition of 0.1 mol/L NaHCO₃ and characterized by means of （infrared） absorption spectroscopy（IR） and electrochemical impedance spectroscopy（EIS）. The Nyquist plots for non-doped PPy in an acid solution（pH=4.01）, a neutral solution（pH=6.85）, and an （alkali） solution（pH=9.14） were composed of two semicircles in the high and mid frequency regions and a Warburg response arisen by H⁺ diffusion process in the low frequency region. The Nyquist plots for HCO^-₃-doped PPy in corresponding pH buffer solutions were composed of two semicircles in the tested frequency （region） and did not show the Warburg response. In the latter case, the charge transfer resistance and the film resistance of PPy were increased apparently. The electrochemically synthesized non-doped PPy as a pH-indicator electrode had satisfactory potentiometric properties:sub-Nernstian response with a slope of 49.32 mV/pH at buffer solutions of pH 3 to 10, excellent linearity, r=-0.997 1, and relatively short response time and small selectivity （coefficient） to conventional positive ions such as K⁺ and Na⁺.更多还原