The limiting current for reduction of ferricyanide ion at nickel: The importance of experimental conditions

Abstract

in Wiley InterScience (www.interscience.wiley.com).Steady state, hydrodynamic voltammetry is a well-established technique to measure the rate of mass transport of an electroactive species to, or from, a solid surface electrode in an aqueous electrolyte. Limiting current measurements during the reduction of ferricyanide (hexacyanoferrate III ) ion at a nickel rotating disc electrode (RDE) are critically considered, and the accuracy of the technique is quantitatively assessed. The importance of surface pretreatment, type of indifferent electrolyte, and the effect of sunlight are considered. Limiting current values can show large deviations from the values predicted by the Levich equation for laminar flow to a polished RDE when unsuitable conditions are employed, despite the appearance of well-defined limiting current plateaux. Using appropriate pretreatment and experimental procedures, the averaged mass transport coefficients or limiting currents values can be obtained, which are close to the values predicted by the Levich equation for laminar flow to a hydrodynamic smooth RDE. 2008 American Institute of Chemical Engineers AIChE J, 54: [802][803][804][805][806][807][808][809][810] 2008 Keywords: activation of electrodes, convective diffusion, electrochemical mass transport, ferricyanide hexacyanoferrate(III) ion, nickel electrode surfaces, limiting current, rotating disc electrode, pretreatment of electrode surfaces, RDE, voltammetry IntroductionThe establishment of any electrochemical processes requires feasibility and process design studies. These preliminary works are normally carried out on pilot-scale laboratory electrolysers or in small laboratory electrochemical cells, and are essential to design the electrochemical reactor. The successful scale-up from laboratory to industry depends in great measure on the guidance obtained from the results of these investigations and from the continuous evaluation of the process after being implemented. The limiting currentThe most important figures of merit to be determined during the preliminary studies are often the current efficiency,

Synthesis and characterization of carbon black/manganese oxide air cathodes for zinc–air batteries: Effects of the crystalline structure of manganese oxides

“…The above significant difference in the limiting current density of the ORR measured by the RRDE method is attributed to combined effects of several factors, such as the intrinsic activity (e.g., electron transfer number), the catalyst mass/thickness on the disk electrode [43], and the surface roughness of catalysts coated onto the disk electrode [44,45].…”

Simultaneous Spatial and Temporal Measurements of the Current Distribution in a Miniature Hull Cell

“…Finally, electrochemical pre-treatment was conducted using the electrolyte without ferri/ferrocyanide, evolving hydrogen as prescribed in previous studies. 24 To ensure a large surface area counter electrode, a 50 mesh nickel gauze with wire diameter of 50 μm (Alfa Aesar) was used, with dimensions of 20 mm × 30 mm.…”

The filter-press FM01-LC laboratory flow reactor and its applications

“…Reactions (5) and (6) are well established choices for model mass transport measurements at inert electrode materials [35].…”

“…1 cm and a nominal flow channel volume of ca. 35.cm 3 . This rectangular flow channel is fed by four distributor channels which take the external electrolyte through a circular tube of area 0.5 cm 3 .…”