Catalyst-selective, scalable membraneless alkaline direct formate fuel cells

• A catalyst-selective strategy is proposed for development of membraneless DLFCs.
• A safe, inexpensive alkaline aqueous formate solution is used as an anolyte/fuel.
• The membraneless DFFC system is scalable without configuration limitations.
• Both facile anode and cathode reactions can be realized in membraneless DFFCs.
• Aqueous formate fuel shows superior oxidation kinetics to other liquid fuels.

We present here a membraneless alkaline direct formate fuel cell (DFFC) with a catalyst-selective strategy, in which a non-hazardous, inexpensive alkaline aqueous formate solution is used as an anolyte. The novel catalyst-selective strategy not only avoids the use of practically unviable alkaline anion-exchange membranes, but also overcomes the scalability limitation of the traditional membraneless DLFCs that are based on a micro-flow phenomenon, and allows the development of large-scale membraneless DLFCs with flexible configurations. In comparison to methanol, ethanol, and formic acid fuels, the aqueous formate solutions show superior oxidation kinetics and efficiency. The high power density exhibited by the membraneless alkaline DFFC is promising for developing small, safe, inexpensive portable power systems as well as large-scale energy generation systems.

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