Self-induced convection as a built-in mass transport accelerator in photoelectrochemical glycerol valorization Heejung Kong 1, 2 , Roel van de Krol 1, 2 , Marco Favaro 1 1 Institute for Solar Fuels, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany, 2 Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, 10623 Berlin, Germany Glycerol, a major by-product of biodiesel production, has the potential to be electrochemically oxidized into higher- value chemicals. This study examines self-induced convection in a photoelectrochemical (PEC) device capable of simultaneously valorizing glycerol and generating green hydrogen. This convection arises naturally from hydrogen bubble evolution and density gradients, and plays a key role in enhancing mass transport. To this end, we combine multiphysics modeling—coupling charge transfer, gas evolution, fluid flow, and species transport—with in situ pH imaging to elucidate the origin and morphology of the self-induced convection and to quantify its impact on mass transfer. Furthermore, we design a new batch-type PEC device in which the reaction chamber is spatially separated from the product-collection chamber, and an upward bubble plume functions as a built-in natural pump. These findings establish design guidelines for pump-free PEC reactors that unite reaction and separation in a single, energy-efficient platform.
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© The Author(s), 2025
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