The production of “green” hydrogen via electrolysis is seen as a key decarbonization pathway for certain industry sectors, but its efficiency can be hampered by a number of factors, including the accumulation of gas bubbles on electrode surfaces within electrolyzers and issues related to membrane durability and complexity. Gas bubble formation in particular can lead to a reduction in electrolyte contact area on the electrode and decrease overall ionic conductivity. Research has pointed to the use of certain organic additives, such as glycerol, as a way to reduce bubble creation and also eliminate the reliance on membranes in electrolyzer systems. This approach pairs the hydrogen evolution reaction (HER) with the glycerol electrochemical oxidation reaction (GEOR), but challenges arise due to gylcerol’s high viscosity and low conductivity, and these problems are exacerbated at the high glycerol concentrations required to promote GEOR activity and suppress oxygen bubble formation.
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A team of researchers from the National Taiwan University of Science and Technology (www.ntust.edu.tw) have devised a novel reactor setup to better support HER-GEOR electrolysis integration, and their findings were published in a recent edition of Sustainable Chemistry and Engineering. Their novel dual-rotor spinning disc reactor (DR-SDR) is designed for uniform current-density distribution and optimized transport of viscous, low-conductivity electrolytes, while enabling faster detachment of gas bubbles.
Traditional spinning-disc reactors, which are widely used in industry, are known for their ability to generate strong shear forces and thin liquid films from their centralized hub for liquid inflow. However, they struggle to provide electric-field uniformity due to their asymmetric single-disc configuration. The dual-rotor design of the DS-SDR synergistically combines conventional hub inflow and disc rotation, and has demonstrated a 25% increase in mass transfer when compared to traditional spinning-disc reactors.
The ability to better utilize organic components in electrolysis not only supports efficient, membrane-less hydrogen production, it also enables the co-production of high-value organic acids, and the potential application of renewable feedstocks, since glycerol can be readily obtained from plant-based materials, recycled vegetable oils and other waste streams.