The importance of identifying the true catalyst when using Randles-Sevcik equation to calculate turnover frequency

Water splitting will become important to store excess renewable electrical energy into hydrogen. Although the oxygen-evolution reaction (OER) by water oxidation is a critical reaction for water splitting, further investigations are needed to find the details of the OER mechanism for various electroc...

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Bibliographic Details
Published in:International journal of hydrogen energy Vol. 46; no. 76; pp. 37774 - 37781
Main Authors: Abdi, Zahra, Vandichel, Matthias, Sologubenko, Alla S., Willinger, Marc-Georg, Shen, Jian-Ren, Allakhverdiev, Suleyman I., Najafpour, Mohammad Mahdi
Format: Journal Article
Language:English
Published: Elsevier Ltd 03.11.2021
Subjects:
Metal complex
Precatalyst
Randles-Sevcik equation
True catalyst
Water oxidation
Metal complex
True catalyst
Precatalyst
Randles-Sevcik equation
Water oxidation
ISSN:0360-3199, 1879-3487
Online Access:Get full text
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Summary:Water splitting will become important to store excess renewable electrical energy into hydrogen. Although the oxygen-evolution reaction (OER) by water oxidation is a critical reaction for water splitting, further investigations are needed to find the details of the OER mechanism for various electrocatalysts. More in particular for homogeneous electrocatalysts, the Randles-Sevcik equation has been extensively applied to determine the turnover frequency (TOF). Herein, using vitamin B12 as a case study, we show that the dynamical deposition/dissolution of the heterogeneous catalyst during OER makes the Randles-Sevcik equation too complicated to be used for calculating the TOF. Indeed, the conventionally applied post-characterization methods do not provide sufficient accuracy to prove the homogeneity of OER mechanisms; thus, using the Randles-Sevcik equation to calculate the TOF is not necessarily correct. The importance of the formed heterogeneous catalyst on the calculation of turnover frequency was highlighted. [Display omitted] •Vitamin B12 was investigated under oxygen-evolution reaction.•Vitamin B12 is the precatalyst rather than the true catalyst for oxygen-evolution reaction.•Randles-Sevcik equation could not be used when dynamical deposition/dissolution of the catalyst occurs.
ISSN:0360-3199
1879-3487
DOI:10.1016/j.ijhydene.2021.09.039