Understanding Selectivity in the Chlorate Process: A Step towards Efficient Hydrogen Production
Journal article, 2018

Chlorate production is a highly energy demanding industrial process, where chlorate formation is accompanied with hydrogen formation on the cathode. To ensure a high cathodic current efficiency, sodium dichromate is added to the chlorate electrolyte to avoid reduction of hypochlorite formed as a reaction intermediate in the process. However, chromate is highly toxic to humans and environment, and therefore a replacement is desired. A model system with ex situ formed chromium oxide/hydroxide films were used to study hypochlorite reduction and hydrogen evolution. The experimental results demonstrate that the hypochlorite reduction is fully blocked while hydrogen evolution readily occurs. However, in the presence of hypochlorite the hydrogen evolution reaction is inhibited. By combining experimental findings with density functional theory (DFT) calculations, the mechanism of hypochlorite reduction was revealed and the reason for inhibition by the deposited chromium(III) film was demonstrated. Based on these results possible replacements for chromate are suggested.

Density Functional Theory

Reaction mechanism

Hypochlorite reduction




Adriano Gomes

Akzo Nobel - Pulp and Performance Chemicals

University of Gothenburg

Michael Busch

Chalmers, Physics, Chemical Physics

Mats Wildlock

Akzo Nobel - Pulp and Performance Chemicals

Nina Simic

Akzo Nobel - Pulp and Performance Chemicals

Elisabet Ahlberg

University of Gothenburg


2365-6549 (eISSN)

Vol. 3 23 6683-6690

Subject Categories

Inorganic Chemistry

Materials Chemistry

Other Chemical Engineering



More information

Latest update