An HMV mapping study of a pulsating jet system

Abstract

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.

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

“…However, in the course of previous investigations, mapping of the electrochemical response of the system identified some unusual characteristics [2]. First, the current pulses produced by this apparatus exhibited a strong 'ring' like relationship with the edge of the jet mouth [2]. Second, the size of the electrode surround (or support) also affected the mapping data, with a 'halo' effect detected.…”

“…Oscillation of the membrane was driven by a mechanical shaker (a Model V4, Signal Force, Data Physics Ltd) attached to the centre of a piston/membrane assembly (note although the piston assembly provided significantly improved HMV performance when compared to the membrane system, both will be used in the results discussed here). Figure 1 shows a schematic of a section of the pulsating jet apparatus imaged in the experiments reported here with particular reference to the region of direct interest where the imaging and electrochemical scanning experiments where concentrated [2]. Note variants of the complete apparatus can be found described previously in more detail [1][2][3].…”

“…In addition, the detection limit of the system [3] and its use to investigate nanostructured [19][20][21] electrodes has been demonstrated [1]. However, in the course of previous investigations, mapping of the electrochemical response of the system identified some unusual characteristics [2]. First, the current pulses produced by this apparatus exhibited a strong 'ring' like relationship with the edge of the jet mouth [2].…”

“…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.…”

“…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. For example, this approach has been used to investigate HMV behaviour of a variety of redox systems [2,3,18]. In addition, the detection limit of the system [3] and its use to investigate nanostructured [19][20][21] electrodes has been demonstrated [1].…”