利用扫描电化学显微镜研究过氧化氢检测中电化学消除抗坏血酸

Electrochemical Depletion of Ascorbic Acid in the Detection of Hydrogen Peroxide——An Investigation Using SECM

利用扫描电化学显微镜 (SECM)将微探针定位于宏观金盘基底电极的扩散层内 .通过向基底电极施加适当电位以氧化消除电活性干扰物质 (如抗坏血酸 ) ,提高探针电极检测过氧化氢的选择性 .基于此方法 ,系统研究了探针 -金基底电极间距和电极电位对铂微探针检测过氧化氢选择性的影响 .结果表明 ,当探针 -基底电极间距为 2 2 .6μm ,金基底电极和铂探针电极电位分别为 0 4V和 0 5V时 ,探针电极检测过氧化氢不受抗坏血酸 ( 0 0 5mmol·L-1)的干扰 .此时 ,过氧化氢检测的线性范围为 :4× 10 -5～ 1× 10 -3 mol·L-1.基于实验结果 ,提出了在微型化电化学器件制备过程中设计互相靠近的双工作电极 ,利用电化学法消除电活性干扰物以提高检测选择性的新方法 .

An electrochemical method for detection of hydrogen peroxide has been advocated via selective elimination of interferences (i.e., ascorbic acid). In this method, the elimination of the interferences was achieved by positioning a tip electrode of scanning electrochemical microscopy (SECM) in the diffusion layer of an Au electrode and meanwhile applying a suitable potential on the substrate. Influence of the tip-substrate distance and the potentials of tip- and substrate-electrode on the selectivity and sensitivity of hydrogen peroxide detection was systematically investigated. Results showed that highly selective and sensitive detection of hydrogen peroxide free from interference of ascorbic acid (0.05 mmol (.) L-1) could be obtained when the tip-substrate distance was 22.5 mum and the tip and substrate potentials were 0.5 and 0.4 V, respectively. The linear range for hydrogen peroxide detection is 4 X 10(-5) similar to 1 X 10(-3) mol (.) L-1. Finally, potential application of the present method in fabrication of micro-electrochemical sensing devices has been discussed.