posted on 2019-08-20, 16:39authored byJohannes
G. Vos, Zhichao Liu, Florian D. Speck, Nickson Perini, Wentian Fu, Serhiy Cherevko, Marc T. M. Koper
The
electrochemical chlorine evolution reaction (CER) and oxygen
evolution reaction (OER) represent core processes in the production
of chlorine, relevant to bulk chemical manufacturing, and water splitting,
the most promising technology for renewable energy storage. Unfortunately,
because of an apparent coupling between their key binding intermediates,
the two reactions can easily occur simultaneously, which is never
an attractive outcome. In this work, using a series of iridium-based
double perovskites and rotating ring-disk voltammetry to deconvolute
parallel OER and CER currents, we explored the interdependence of
CER and OER in dilute acidic chloride solutions of up to 120 mM, where
both reactions may occur in parallel with similar current densities.
We also employed online inductively coupled plasma-mass spectrometry
(ICP-MS) measurements to probe the material stability and its dependence
on chloride concentration. For all studied materials, we found a strong
linear correlation between CER and OER activity as well as a comparable
selectivity, strengthening the suggestion that OER and CER follow
a scaling relationship. It was also found that chloride selectively
enhances the dissolution of the noble metal component. A reaction
order analysis was performed to gain insight into the CER mechanism,
the effect of surface area changes due to adventitious leaching, and
the observed suppressing effect of chloride on OER.