Chemical industry is one of the major consumers of fossil fuels and the use of fossil fuels creates environmental challenges such as emission of greenhouse gases, global warming, etc. In this context, renewable energy sources have gained great attention throughout the world. In this context, organic electrosynthesis can be identified as an attractive route to sustainable chemical manufacturing. However, use of organic electrosynthesis in the industry has been restricted because of mass transport limitations. Although traditionally electrode fouling considered as detrimental due to loss of electroactive are, in the present study, we demonstrate that controlled, partial fouling can instead enhance electrosynthetic performance by inducing density gradient–driven natural convection. Laterally heterogeneous electrodes, comprising conductive regions interspersed with insulating domains, generate buoyancy-driven flows under gravity that augment mass transport in otherwise quiescent electrolytes.
We quantitatively evaluated this effect for the electroreduction of levulinic acid to valeric acid and electrooxidation of l-ascorbic acid to dehydroxyascorbic acid by using high performance liquid chromatogram or gas chromatography- mass spectrometry techniques. As the working electrode, we used photolithographically patterned glassy carbon or lead electrode. Despite a reduction in electroactive surface area, patterned electrodes consistently delivered higher area-normalised reaction rates and product yields than pristine electrodes. Hydrophilic novolak resin (nLOF 2035) patterns enhanced levulinic acid conversion by up to 1.8-fold, while SU-8 2002 features increased ascorbic acid oxidation rates by 1.22-fold. Additional rate enhancements (1.5-fold compared to the horizontal cell) were achieved by vertically orienting electrodes to maximise buoyancy-driven convection.
These results challenge the prevailing paradigm that electrode fouling is inherently deleterious and establish controlled surface heterogeneity as a powerful design principle for enhancing mass transport and performance in organic electrosynthesis.