Utilizing carbon dioxide (CO2) as a resource for carbon monoxide (CO) production using renewable energy requires electrochemical reactors with gas diffusion electrodes that maintain a stable and highly reactive gas/liquid/solid interface. Very little is known about the reasons why gas diffusion electrodes suffer from unstable long‐term operation. Often, this is associated with flooding of the gas diffusion electrode (GDE) within a few hours of operation. A better understanding of parameters influencing the phase behavior at the electrolyte/electrode/gas interface is necessary to increase the durability of GDEs. In this work, a microfluidic structure with multi‐scale porosity featuring heterogeneous surface wettability to realistically represent the behavior of conventional GDEs is presented. A gas/liquid/solid phase boundary was established within a conductive, highly porous structure comprising a silver catalyst and Nafion binder. Inoperando visualization of wetting phenomena was performed using confocal laser scanning microscopy (CLSM). Non‐reversible wetting, wetting of hierarchically porous structures and electrowetting were observed and analyzed. Fluorescence lifetime imaging microscopy (FLIM) enabled the observation of reactions on the model electrode surface. The presented methodology enables the systematic evaluation of spatio‐temporally evolving wetting phenomena as well as species characterization for novel catalyst materials under realistic GDE configurations and process parameters.

A new bio-based value chain for microbially accessible hydroxy fatty acids – production of secondary alcohols and alkanes over supported Ru catalyst.

Microfluidic systems offer a multitude of advantages over classical techniques in the fields of biomedical and chemical research. Unit operations such as sample pre‐treatment, mixing, reactions, and especially separation and purification operations can be realized on microfluidic platforms enabling rapid prototyping and facile parallelization on the laboratory scale. However, the fabrication and integration of porous membranes in microfluidics poses several problems. Material development, membrane geometry, and membrane integration are three main questions to be addressed in this context. Herein, a durable and versatile method to anchor free‐form membranes with tunable microgeometry to surfaces, enabling the fabrication of stable, multi‐material microfluidic systems for different potential applications is shown. In addition, the influence of the macro‐ and microgeometry that is the shape and porosity of a membrane on key performance indicators such as diffusivity and permeation of tracer molecules is investigated. The presented characterization methods will enable a better understanding of microfluidic modules with incorporated membranes.

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