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Download fileSelective Hydrogen Evolution on Manganese Oxide Coated Electrodes: New Cathodes for Sodium Chlorate Production
journal contribution
posted on 15.06.2019, 00:00 authored by Balázs Endrődi, Aleksandra Stojanovic, Maria Cuartero, Nina Simic, Mats Wildlock, Roland de Marco, Gaston A. Crespo, Ann CornellThe safety and feasibility
of industrial electrochemical production
of sodium chlorate, an important chemical in the pulp and paper industry,
depend on the selectivity of the electrode processes. The cathodic
reduction of anodic products is sufficiently suppressed in the current
technology by the addition of chromium(VI) to the electrolyte, but
due to the high toxicity of these compounds, alternative pathways
are required to maintain high process efficiency. In this paper, we
evaluate the electrochemical hydrogen evolution reaction kinetics
and selectivity on thermally formed manganese oxide-coated titanium
electrodes in hypochlorite and chlorate solutions. The morphology
and phase composition of manganese oxide layers were varied via alteration
of the annealing temperature during synthesis, as confirmed by scanning
electron microscopy, X-ray diffraction, synchrotron radiation X-ray
photoelectron spectroscopy, and near-edge X-ray absorption fine structure
spectroscopy measurements. As shown in mass spectroscopy coupled electrochemical
measurements, the hydrogen evolution selectivity in hypochlorite and
chlorate solutions is dictated by the phase composition of the coating.
Importantly, a hydrogen evolution efficiency of above 95% was achieved
with electrodes of optimized composition (annealing temperature, thickness)
in hypochlorite solutions. Further, these electrode coatings are nontoxic
and Earth-abundant, offering the possibility of a more sustainable
chlorate production.
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Keywords
manganese oxide layersnear-edge X-ray absorptionSelective Hydrogen Evolutionchlorate solutionsphase compositionhypochloritestructure spectroscopy measurementsmanganese oxide-coated titanium electrodeshydrogen evolution efficiencyhydrogen evolution selectivityelectrochemical hydrogen evolution reaction kineticsscanning electron microscopysynchrotron radiation X-ray photoelectron spectroscopycoatingannealing temperatureSodium Chlorate ProductionManganese Oxide Coated Electrodes