Novel Superaerophobic Anode with Fern‐Shaped Pd Nanoarray for High‐Performance Direct Formic Acid Fuel Cell

Abstract Direct formic acid fuel cells (DFAFCs) possess the advantages of high power density and theoretical cell potential. Exploring robust catalysts for electrochemical formic acid electro‐oxidation (FAO) is greatly essential for the wide spread uptake of DFAFCs. However, many electrodes with attractive catalysts suffer limited mass transport due to sluggish CO₂ bubble growth and departure steps on its surface. In this study, a superaerophobic electrode is developed by depositing fern‐shaped palladium nanostructured arrays on the carbon paper (Pd‐nanoarray@CP). Its unique superaerophobic feature successfully facilitates the CO₂ bubble releasing from the catalyst surface in a significantly small size. With the merits of specific nanoarray morphology, superior under water superaerophobicity, and rapid gas bubble release, the Pd‐nanoarray@CP shows fast charge/mass transport rate, high electrocatalytic activity, and great stability for FAO. A direct formic acid fuel cell equipped with the Pd‐nanoarray@CP anode is successfully fabricated on a microfluidic platform. A peak power density of 35.8 mW cm⁻² and limiting current density of 173.3 mA cm⁻² are obtained, respectively, which are 49.2% and 33.0% higher than that of conventional Pd‐black anodes. The electrode with superaerophobic interface allows deeper insight into the mechanism of FAO efficiency and holds promise for possible applications of commercially viable DFAFCs.