Highly Active and Durable PdAg@Pd Core–Shell Nanoparticles as Fuel‐Cell Electrocatalysts for the Oxygen Reduction Reaction

Abstract

By controlling the surface structure and composition at the atomic level, the catalytic properties of bimetallic alloy catalysts can be precisely and effectively tuned, and their activity and durability can be enhanced. Here, a class of highly active and durable PdAg bimetallic alloy nano‐electrocatalysts is demonstrated by tuning the surface composition through a simple electrochemical treatment process in acid medium. Transmission electron microscopy, X‐ray photoelectron spectroscopy, and cyclic voltammogram measurements clearly show the well‐defined core–shell structure that consists of a PdAg alloy core and a few atomic layers of Pd as the shell (PdAg@Pd). Compared to pure Pd and Ag catalysts, the prepared PdAg@Pd/C exhibits enhanced electrocatalytic activity and durability for the oxygen reduction reaction in alkaline media. According to the theoretical and experimental results, the enhanced electrocatalytic activity can be attributed to the synergistic effects between the Pd and the Ag, while the durability is ascribed to the unique alloy core–ultrathin‐Pd‐shell structure of the PdAg@Pd/C catalyst. This study not only proposes a simple and straightforward approach for preparing highly monodisperse PdAg alloy nanoparticles and designing advanced electrocatalysts for fuel cells, but also demonstrates the crucial effect of electrochemical treatment on the electrocatalytic properties of catalysts.

Advanced yolk-shell nanoparticles as nanoreactors for energy conversion

“…Recently, highly active and durable PdAg@Pd core-shell nanoparticles were prepared and were shown to be a good potential ORR catalyst. PdAg bimetallic alloy nanoparticles of size approximately 6 nm were prepared via oleylamine reduction of Pd and Ag precursors, and ultrathin Pd shells were formed by electrochemical treatment (100 cycles of electrocatalysis) of the PdAg alloy in an acidic medium [133]. The electrocatalytic activity was evaluated by attaching the nanoparticles to active carbon; the nanoparticles showed good catalytic activity and durability in the ORR.…”

Effect of temperature and incident ion energy on nanostructure formation on silicon exposed to helium plasma

“…Quantum confinement effects that emerge at the nanoscale significantly alter electronic band structures in a size-dependent manner, which can be exploited to tune the optical, [1][2][3] electronic [4,5] and catalytic properties [6,7] of a target material. The inherently high surface area of many nanostructures (such as wires [8,9] and porous meshes [10] ) also makes them attractive candidates for high-performance catalysts, [11] fuel cell [12] and battery electrodes, [13] and high-sensitivity chemical sensors. [14] Nanostructures can also be used to change other properties, such as changing surface geometry to suppress reflection [15,16] or light-triggered dissolution within biological media.…”

Polyethyleneimine modified AuPd@PdAu alloy nanocrystals as advanced electrocatalysts towards the oxygen reduction reaction

“…At present, Pt-based nanocrystals have been proved to be best cathode catalyst towards the ORR, nevertheless, they suffer from the high cost due to the limited reserves in nature. Recently, a lot of investigations have shown that Pd-based nanocrystals have become highly promising Pt-alternative cathode catalysts towards the ORR in the alkaline electrolyte due to their high catalytic activity and the significantly lower price [10][11][12][13][14][15][16][17][18][19][20] .…”

“…Although significant progress has been made in developing Pdbased ORR cathode catalysts in recent years, they still have some serious disadvantages, including the poor durability and low selectivity towards the ORR [10,[12][13][14][15][16][17][18][19] . On the one hand, Pd has much lower intrinsic electrochemical stability relative to Pt due to the low redox-potential of Pd element, resulting in poor durability in electro-catalyzing ORR.…”