Submicromolar analysis with rotating and hydrodynamically modulated disk electrodes

2009

The electrochemistry of nanostructured electrodes is investigated using hydrodynamic modulated voltammetry (HMV). Here a liquid crystal templating process is used to produce a platinum modified electrode with a relatively high surface area (Roughness factor, Rf = 42.4). The electroreduction of molecular oxygen at a nanostructured platinum surface is used to demonstrate the ability of HMV to discriminate between faradaic and non-faradaic electrode reactions. The HMV approach shows that the reduction of molecular oxygen shows considerable hysteresis correlating with the formation and stripping of oxide species at the platinum surface. Without the HMV analysis it is difficult to discern the same detail under the conditions employed. In addition the detection limit of the apparatus is explored and shown, under ideal conditions, to be of the order of 45 nmol dm -3 employing [Fe(CN) 6 ] 4-as a test species.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Exploring the applications of a pulsating jet hydrodynamic modulated voltammetric (HMV) system – Electrochemistry of nanostructured Pt electrodes and trace analysis

2009

“…Early examples include a modified rotating disk experiment whereby the frequency of rotation of the disk is modulated at an appropriate level [5][6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

An HMV mapping study of a pulsating jet system

2008

A new system for the generation of hydrodynamic modulated voltammetry (HMV) is presented. This system consists of an oscillating jet produced through the mechanical vibration of a large diaphragm. The structure of the cell is such that a relatively small vibration is transferred to a large fluid flow at the jet outlet. ) it can also be used to create a HMV system where a 'lock -in' approach is adopted to investigate the redox chemistry in question. This is demonstrated for the Fe(CN) 6 3-/4-redox system. Here 'lock -in' to the modulated hydrodynamic signal is achieved through the deployment of bespoke software. The apparatus and procedure is shown to produce a simple and efficient way to obtain the desired signal. In addition the spatial variation of the HMV signal, phase correction and time averaged current with respect to the jet orifice is presented.

“…The investigation of the characteristics of a pulsating jet [1][2][3] for hydrodynamic modulated voltammetry (HMV) [4][5][6][7][8][9][10][11][12][13][14][15][16][17] applications has been reported in a number of previous articles. In brief, the apparatus (an inverted funnel and a narrow (~ 2 mm in diameter) jet orifice, produces a reproducible hydrodynamic pulse of liquid which can, in combination with electrochemical apparatus, be useful.…”

Section: Introductionmentioning

confidence: 99%

Understanding the spatial mass transfer behaviour of a pulsating jet HMV system – Vortex generation and characterisation

2013

The flow patterns generated by a pulsating jet used to study hydrodynamic modulated voltammetry (HMV) are investigated. It is shown that the pronounced edge effect reported previously is the result of the generation of a vortex ring from the pulsating jet. This vortex behaviour of the pulsating jet system is imaged using a number of visualisation techniques. These include a dye system and an electrochemically generated bubble stream. In each case a toroidal vortex ring was observed. Image analysis revealed that the velocity of this motion was of the order of 250 mm s -1 with a corresponding Reynolds number of the order of 1200. This motion, in conjunction with the electrode structure, is used to explain the strong 'ring and halo' features detected by electrochemical mapping of the system reported previously.