Enhanced formic acid oxidation with Pd nanoparticles deposited on boron-doped graphene: A comprehensive electrochemical and spectroscopic investigation

Herein, nanostructured Pd electrocatalysts with boron-doped graphene (Pd/B-G) are prepared towards the formic acid oxidation. The catalysts are characterized by Raman spectroscopy, X-ray powder diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma optical emission spectrometer (ICP-OES). The boron atoms have been successfully doped into graphene in the forms of BC3, BC2O and BCO2 to create abundant defect sites, which contributes to subsequent dispersion of Pd nanoparticles (NPs). The TEM results confirm that more fine and homogeneous distribution of Pd NPs on B-G than those on native graphene. XPS-Pd3d band shows a little shift to lower binding energy and the higher metallic Pd content on Pd/B-G compared with to not doping boron (Pd/G) due to the electrons transfer from B-G to Pd. The electrochemical evaluation shows that Pd/B-G catalyst achieves much enhanced activity as well as improved catalytic stability compared to those of Pd/G and commercial Pd/C. The enhanced performance is not only ascribed to the higher dispersion the utilization efficiency of Pd, but also attributed to the electronic interaction between Pd NPs and B-G support. This co-effect also can facilitate the formation of metallic Pd and provide more active sites, as well as lowers d-band center of Pd and thus weakens the absorption of the COads on Pd.