PdAu alloyed clusters supported by carbon nanosheets as efficient electrocatalysts for oxygen reduction

Abstract

PdAu alloyed clusters supported on carbon nanosheets were prepared and employed as efficient electrocatalysts for oxygen reduction reaction (ORR). PdAu clusters protected by glutathione were synthesized, while the structure and composition of the alloys were tuned through the variation of Pd-to-Au ratio. The PdAu clusters were loaded into carbon nanosheets and calcined at elevated temperature. The protecting ligands were completely removed after calcination, and uniform hybrid materials were formed. The as-prepared nanocomposites were characterized by transmission electron microscopy (TEM), scanning tunneling electron microscopy (STEM), X-ray photoelectron spectroscopy (XPS), X-ray

Oxygen Reduction Reaction Catalyzed by Noble Metal Clusters

“…For instance, with 0.1 M KOH as the electrolyte, the onset potential, half-wave potential and diffusion-limited current density at 1600 rpm were 0.95 V, 0.84 V and 5.8 mA cm −2 for PtAu porous nanocluster (size:~3 nm), higher than for Pt@Au nanorods dispersed on pyridyne cycloaddition of graphene (size:~20 nm in width, 0.89 V, 0.67 V and 5 mA cm −2 ) [90]. Under almost the same conditions, the Au 67 Pd 33 clusters supported on carbon nanosheets (Au 67 Pd 33 /CNs) [73] also exhibited more positive onset potential than AuPd alloy nanocrystals with reduced graphene oxide [91] (AuPd/rGO, size: 22.5 nm) (0.94 V for Au 67 Pd 33 /CNs vs. 0.92 V for AuPd/rGO) and higher half-wave potential than reduced graphene oxide-supported asymmetric Au-core Pd-shell bimetallic nanoparticles [92] (Au@Pd/rGO, size: 15 nm) (0.83 V for Au 67 Pd 33 /CNs vs. 0.80 V for Au@Pd/rGO). The above comparison further features the great advantages of employing metal clusters as highly efficient catalysts for ORR.…”

“…The reaction kinetics was then elucidated by extrapolating the Tafel slope from the Tafel plots (Figure 5d), and the Au 67 Pd 33 /CNs sample displayed a slope of 67.7 mV dec −1 , close to that of Pt/C (64.4 mV dec −1 ). In addition, this sample also exhibited markedly superior long-term stability than that of Pt/C [73]. …”

“…Recently, Feng and Xu developed a wet chemical approach to fabricate monodispersed porous dendrite-like PtAu porous nanoclusters for ORR and methanol oxidation by employing L -histidine as the structure-director and PVP as the dispersing agent [76]. In a recent report, our group described the preparation of AuPd clusters supported by porous carbon nanosheets in alkaline media [73]. In this study, a series of composites with different Au: Pd ratios (100:0, 80:20, 67:33, 50:50, 33:67, 20:80, 0:100) was prepared, and the electrocatalytic performance toward ORR is depicted in Figure 5.…”

PRELIMINARY STUDY ON Pd-BASED BINARY CATALYSTS SUPPORTED WITH CARBON NANOFIBER FOR THE ELECTROOXIDATION OF GLYCEROL

“…The diffraction peak positions for PdAu/CNF, move which located between two wavelengths at each monometallic nanoparticle for Pd and Au. This indicates that, Au has entered Pd lattice and form a homogeneous substitution alloy [19]. BET analysis has been conducted to evaluate the specific area of the catalyst support to ensure the pore of the support has been filled in the catalyst.…”

“…The addition of Au as second metal in PdAu/CNF also contribute to sufficient oxygen containing species such as OH to remove the adsorbed carbonaceous species and in other way it will beneficial in oxidation of glycerol [19]. Meanwhile the catalyst poisoning against the carbonaceous species can be traced from the forward scan to backward (If/Ir) scan peak current density ratio as shown in Table 2.…”