Nickel 3D Structures Enhanced by Electrodeposition of Nickel Nanoparticles as High Performance Anodes for Direct Borohydride Fuel Cells

Abstract

Direct borohydride fuel cell (DBFC) is a promising technology to power portable and mobile devices thanks to their high theoretical voltage and good energy density. Carbon-supported electrodeposited nickel-metal catalysts (NiED/C) exhibit fast kinetics for the borohydride oxidation reaction (BOR). One key is to deposit nickel-metal on sufficiently open structures to make electrodes compatible with fast mass-transfer, so as to further optimize the fuel cell performance. To that goal, Ni foams (NFM) or felts (NFT) can be used. Being inherently surface-oxidized (passivated) and of too low developed area, these supports were enhanced by both oxides removal/depassivation (using electro-assisted (or not) acid etching) and nickel electrodeposition, in order to exhibit the combined properties of fast diffusion medium and high-surface area resulting in the highly-active catalysts. After such enhancement, NiED/NFT shows superior performance in the BOR compared to carbon-supported Ni catalysts. To make a fair comparison with PGM, Pt catalysts supported on open carbon structures were also studied and presented slightly smaller performance than the NiED/NFT electrodes, in particular in terms of open-circuit potential and current density at high cell voltage.