Automated Microfluidics for Efficient Characterization of Cyclohexanol Electrooxidation for Sustainable Chemical Production.

The electrochemical conversion of biomass-derived compounds into value-added chemicals using renewable electricity has attracted attention as a promising pathway for sustainable chemical production, with the electrooxidation of cyclohexanol being a typical example. However, optimizing and upscaling these processes have been hindered due to a limited understanding of the underlying mechanisms and limiting factors. To address this, there is a critical need for experimental tools that enable more efficient and reproducible measurements of these complex processes. In this work, we develop an automated microfluidic platform and use it to conduct controlled and efficient measurements of cyclohexanol electrooxidation on nickel electrodes under various electrolyte compositions and flow rates. The platform features microchannel networks integrated with multiple analytical instruments such as pumps, an electrochemical workstation, and a digital microscope to perform laboratory functions including electrolyte preparation, reaction control, microscopy, and electrochemical characterization, all streamlined through automation. Cyclohexanol electrooxidation on nickel is found to follow Fleischmann's mechanism, with an irreversible heterogeneous reaction as the rate-determining step. The effects of ionic and nonionic surfactant additives are screened, both demonstrating the ability to enhance current densities through different mechanisms. The developed platform is readily transferable for measuring other power-to-chemical processes and is believed to be a powerful tool for accelerating the understanding and development of sustainable electrosynthesis.