Redox Cycling in Nanoscale-Recessed Ring-Disk Electrode Arrays for Enhanced Electrochemical Sensitivity
Redox Cycling in Nanoscale-Recessed Ring-Disk Electrode Arrays for Enhanced Electrochemical Sensitivity
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DOI：
10.1021/nn401542x
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发表时间：
2013-06-01
期刊：
影响因子：
17.1
通讯作者：
Bohn, Paul W.
中科院分区：
文献类型：
--
作者：
Ma, Chaoxiong;Contento, Nicholas M.;Bohn, Paul W.
An array of nanoscale-recessed ring-disk electrodes was fabricated using layer-by-layer deposition, nanosphere lithography, and a multistep reactive ion etching process. The resulting device was operated in generator-collector mode by holding the ring electrodes at a constant potential and performing cyclic voltammetry by sweeping the disk potential in Fe(CN)(6)(3-/4-) solutions. Steadystate response and enhanced (similar to 10x) limiting current were achieved by cycling the redox couple between ring and disk electrodes with high transfer/collection efficiency. The collector (ring) electrode, which is held at a constant potential, exhibits a much smaller charging current than the generator (disk), and it is relatively insensitive to scan rate. A characteristic feature of the nanoscale ring-disk geometry is that the electrochemical reaction occurring at the disk electrodes can be tuned by modulating the potential at the ring electrodes. Measured shifts in Fe(CN)(6)(3-/4-) concentration profiles were found to be in excellent agreement with finite element method simulations. The main performance metric, the amplification factor, was optimized for arrays containing small diameter pores (r < 250 nm) with minimum electrode spacing and high pore density. Finally, integration of the fabricated array within a nanochannel produced up to 50-fold current amplification as well as enhanced selectivity, demonstrating the compatibility of the device with lab-on-a-chip architectures.
