Investigation of the oxygen evolving electrode in pH-neutral electrolytes: Modelling and experiments of the RDE-cell
2007 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 0019-4686, Vol. 52, no 13, 4513-4524 p.Article in journal (Refereed) Published
A model has been developed to illustrate the complex interplay between the acidifying electrode reactions for oxygen evolution, mass transport and homogeneous reactions in pH-neutral electrolytes. Modelled polarisation curves of the oxygen evolution reaction were verified by polarisation curves experimentally measured in 5 M NaClO4 on a RDE of DSA material. The conditions in the simulations and in the experiments were similar to those in the chlorate process (high ionic strength, 70 degrees C, chromate-containing electrolyte, DSA electrode), in which the oxygen evolution reaction is one of the possible side reactions. The model predicted the concentration gradients of H+, OH-, CrO42- and HCrO4- during oxygen evolution on the RDE. It was found that an important part of the chromate buffering effect at high current densities occurs in a thin (in the order of nanometers) reaction layer at the anode. From comparisons between the model and experiments, a buffering reaction has been proposed. The most likely reaction for the chromate buffering in the investigated system is CrO42- reacting with water to HCrO4- and OH-. In the chlorate process, where chromate is a buffer and oxygen evolution is a side reaction, it is likely that chromate promotes oxygen evolution from OH-.
Place, publisher, year, edition, pages
2007. Vol. 52, no 13, 4513-4524 p.
oxygen evolution, pH buffer, rotating disk electrode, mathematical modelling, chromate
IdentifiersURN: urn:nbn:se:kth:diva-5722DOI: 10.1016/j.electacta.2006.12.048ISI: 000245476100028ScopusID: 2-s2.0-33847359224OAI: oai:DiVA.org:kth-5722DiVA: diva2:10180
QC 20100831. Uppdaterad från submitted till published (20100831).2006-05-112006-05-112010-08-31Bibliographically approved