Alkyne‐Protected AuPd Alloy Nanoparticles for Electrocatalytic Reduction of Oxygen

Abstract

Dodecyne‐capped AuPd alloy nanoparticles of varying compositions were prepared through the co‐reduction of metal‐salt precursors with NaBH4. TEM measurements showed that the particles were largely in the range of 2–6 nm in diameter. XPS studies showed that the atomic Pd concentration varied from 65 to 100 %. Infrared spectroscopic measurements confirmed the bonding attachment of the dodecyne ligands on the nanoparticle surfaces, which rendered the nanoparticles readily dispersible in common organic media. Electrochemically, the resulting nanoparticles exhibited apparent catalytic activity in oxygen reduction with a volcano‐shaped variation with the metal composition. The best performance was identified with the sample composed of 91.2 at % Pd that exhibited a mass activity over eight times better than that of commercial palladium black, and almost twice as good in terms of specific activity. This remarkable performance was accounted for by both alloying with gold and surface functionalization with alkyne ligands that manipulated the electronic interactions between palladium and oxygen species.

Peptide‐FlgA3‐Based Gold Palladium Bimetallic Nanoparticles That Catalyze the Oxygen Reduction Reaction in Alkaline Solution

“…Strong signals at BE≈83.5 and 87.3 eV can be ascribed to the Au 4f 7/2 and Au 4f 5/2 electrons (Figure c) . Conversely, compared with Au 100 , the BE of the Au 4f 7/2 electrons for Au 33 Pd 67 decreased by approximately 0.3 eV, which further confirmed the electron transfer from Pd to Au . In addition, the Au/Pd atomic ratios detected by using XPS are given in Table S1, and the values agree well with the initial loading ratios.…”

“…The high‐resolution spectra of the Pd 3d and Au 4f electrons of Au 33 Pd 67 , Au 100 , and Pd 100 are shown in Figure b and c. The Pd 3d spectra of Au 33 Pd 67 and Pd 100 can be deconvoluted into two doublets. The pairs at lower binding energies (BE≈335.2 and 340.7 eV) agree well with metallic Pd, whereas the pairs at higher energies (BE≈337.5 and 342.6 eV) could be ascribed as Pd II species (Figure b). This indicates the formation of a substantial amount of palladium oxide.…”

“…Deming et al. documented alkyne‐protected AuPd NPs for the ORR, and the best performance was identified with a sample composed of 91.2 % Pd . Recently, our group demonstrated the fabrication of supported ultra‐small AuPd clusters for the ORR, and a comparable activity with a markedly higher stability than commercial Pt/C was obtained .…”

“…The most widely employed catalysts for the ORR are Pt‐ and/or Pt‐based nanomaterials, however, the high price and limited earth abundance of Pt as well as the low stability of such catalysts hinders the widespread commercialization of fuel cells significantly. Au and Pd would be an excellent binary alloy as Pd interacts strongly with oxygen and Au does not . Compared to compounds that include only Au or Pd, AuPd alloys have shown an enhanced electrocatalytic activity toward ORR .…”

Ultrasmall Palladium Nanoclusters Encapsulated in Porous Carbon Nanosheets for Oxygen Electroreduction in Alkaline Media

“…In the right panel, the Pd 3d spectra can be deconvoluted into two doublets. [41] Significantly, the series of Pd/CNS nanocomposites exhibited remarkable electrocatalytic activity toward ORR. [35] This suggests the formation of palladium oxide in the samples.…”