Understanding the catalytic active sites of crystalline CoSb2O6 for electrochemical chlorine evolution

07 April 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


The chlorine evolution reaction (CER) is a key reaction in electrochemical oxidation (EO) water treatment. Conventional anodes based on platinum group metals (PGMs) can be prohibitively expensive, which hinders the further application of EO systems. Crystalline cobalt antimonate (CoSb2O6) was recently identified as a promising alternative to conventional anodes due to its high catalytic activity and stability in acidic media. However, its catalytic sites and reaction mechanism have not yet been elucidated. This study sheds light on the catalytic active sites in crystalline CoSb2O6 anodes by using scanning electrochemical microscopy (SECM) to compare the CER catalytic activities of a series of anode samples with different Sb/Co ratios. The results showed that Sb sites served as more active catalytic sites than the Co sites. The varied Sb/Co ratios were also linked with slightly different electronic states of each element, leading to different CER selectivity in chloride solutions. The high activity of Sb sites towards CER highlighted the significance of the electronic polarization that changed the oxidation states of Co and Sb.


Electrochemical oxidation
Scanning electrochemical microscopy
Water treatment

Supplementary materials

Supporting information for: Understanding the catalytic active sites of crystalline CoSb2O6 for electrochemical chlorine evolution
The supporting information contains the setup and redox competition schematic for SECM experiments, CV of the SECM tip and fabricated electrodes, DC and AC response from the SECM piezoelectric positioner, topology of fabricated electrodes, bulk Sb/Co ratio at different potentials, SEM images, EDS mapping, XRD and GIXRD, specific activities, ECSA of fabricated electrodes, and explanation on two scenarios of SECM measurements.


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.