Contribution of Interstitial Boron in a Boron-Incorporated Palladium Catalyst Toward Formate Oxidation in an Alkaline Direct Formate Fuel Cell

Abstract

In this study, boron-incorporated palladium catalysts supported on carbon (PdBInc./C) were synthesized; they exhibited considerably improved catalytic activity for the oxidation of formate (HCOO-). Boron-induced lattice expansion and electronic modification of Pd were observed in this catalyst through various physicochemical analyses. Furthermore, the effective electronic modification between Pd and B was found to overcome the limitation due to the lattice expansion of Pd and the modification was confirmed from the downshift and broadening of the d-band center. The direction of electron transfer was observed from B to Pd. Based on the experimental results, it is possible to infer that PdBInc./C significantly contributes to the weakening of the hydrogen adsorption, which is regarded as a rate-determining step for the oxidation of HCOO-. As an anode electrode, PdBInc./C also showed an outstanding performance in a direct formate fuel cell owing to its modified electronic structure, which is considered an important property to facilitate hygroscopic fuel accessibility in a practical system.