About this Research Topic
Since its first appearance in 2002, microfluidic/nanofluidic fuel cells have grown into a large research community worldwide. Hundreds of research articles have been published ever since, with an increasing trend year by year. A microfluidic/nanofluidic fuel cell is generally composed of two electrodes, confined in a micro channel, which is supplied with anolyte and catholyte from external to ensure a continuous operation. Between the two electrolytes, no physical separation membrane is needed thanks to the low Reynolds number, which allows only slow diffusive mixing instead of vigorous convective mixing. In literature, various cell structures have been proposed, such as the conventional micro channel-based cells (with flow-over or flow-through electrodes), the recent paper-based cells and even the latest thread-based cells. As for the type of reactant, different fuels, oxidants, electrolytes and their free combinations are also explored extensively, proving the great degree of freedom for their design and operation.
Despite the great achievements of the past 20 years, the current microfluidic/nanofluidic fuel cell technology still requires substantial improvements in its power output, energy efficiency, long-term stability, system integration and operation practicability. To this end, both experimental innovation and numerical investigation are highly requested, which can focus on the electro-catalyst preparation, electrode fabrication, channel structure design and fuel cell stacking. Also, in-depth research into the coupling of microfluidics/nanofluidics, heat & mass transport and electrochemistry, especially on the electrode-electrolyte interface, is of great importance to the understanding of cell performance restrictions. Furthermore, the pumpless operation of microfluidic/nanofluidic fuel cells will be a strong propellant to their practical applications, making the whole system much more compact and elegant in both energy density and efficiency. To achieve this goal, passive pumps integrated inside the fuel cell will be required, such as osmotic pumps, evaporation pumps and gravity pumps. Finally, novel cell designs such as paper-based and thread-based fuel cells with capillary electrolyte transport are also highly desired.
All research works related to microfluidic/nanofluidic fuel cells are highly welcome in this Research Topic, including mini reviews, experimental studies and modeling works. The following specific themes are of special interest:
- Non-noble electro-catalysts for electrodes
- 3D flow-through electrodes with high fuel utilization
- Paper-based and thread-based microfluidic/nanofluidic fuel cells
- Microfluidic/nanofluidic fuel cell stacking
- Numerical modeling.
Keywords: microfluidic, nanofluidic, fuel cell, membraneless, mass transport, catalyst, modeling
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