Enhanced Performance of Bimetallic Pd-based Electrocatalysts for Formic Acid Oxidation

Pd-based catalysts supported on high-surface-area carbon are widely used in formic acid fuel cells. The composition, structure, and support can be modified to maximize the capabilities of Pd-based catalysts in terms of catalytic activity, durability, and cost. Various studies have investigated tuning the properties of Pd-based catalysts by alloying Pd with other metals. In this study, Cr, Ni, Cu, and Zn were incorporated into Pd-based catalysts. First, the effects of mole ratios were studied between Pd and the metals. The Pd n Ni ratios on a reduced graphene oxide support (Pd n Ni/rGO) were prepared using the one-pot method without the use of any surfactants. All obtained rGO-supported Pd n Ni catalysts ( n = 1, 2, 4, with diameter of 5 nm) were used for the electrocatalytic oxidation of formic acid. The electro-oxidation measurements revealed that the Pd n Ni/rGO samples had superior electrocatalytic performance both in current densities and stabilities for formic acid oxidation (FAO) compared to Pd/rGO. Furthermore, Pd 4 Ni/rGO had greater electrocatalytic activity than the other Pd n Ni/rGO samples. In addition, with the same mole ratio of metals, Pd 4 Cr/rGO had higher efficiency toward FAO than the other series in the order: Pd 4 Cr/rGO > Pd 4 Ni/rGO > Pd 4 Cu/rGO > Pd 4 Zn/rGO.