Small Trimetallic Au-PdPt Nanoparticles as Multifunctional Catalysts by Simply Engineering Their Pd–Pt Ratios

In this work, small trimetallic Au-PdPt nanoparticles (Au-PdPt NPs) with alloyed Pd–Pt layers composed of different ratios of Pd and Pt were successfully prepared by judiciously adjusting the ratio of Pd and Pt during the one-pot synthesis. Three types of Au-PdPt-NP/C catalysts were further prepared and named as ORR-A-Au52.4-Pd7.7Pt39.9-NP/C catalysts, HER-A-Au55.4-Pd14.5Pt30.1-NP/C catalysts, and ORR-B-Au55.6-Pd33.5Pt10.9-NP/C catalysts. Thanks to the different atomic ratios of Pd and Pt in their alloyed Pd–Pt layers, they can show excellent electrocatalytic performance toward the acidic ORR/HER and the alkaline ORR. For instance, (1) the ORR half-wave potential (E1/2) of ORR-A-Au52.4-Pd7.7Pt39.9-NP/C catalysts in the acidic media is 0.904 V, which is about 52 mV greater than that (0.852 V) of commercial Pt/C catalyst. (2) The HER overpotential at the current density of −10 mA cm–2 (η10) of HER-A-Au55.4-Pd14.5Pt30.1-NP/C catalysts in the acidic media is only 9 mV, which is superior to that (31 mV) of the commercial Pt/C catalyst. (3) The ORR E1/2 of ORR-B-Au55.6-Pd33.5Pt10.9-NP/C catalysts in the alkaline media is 0.935 V, which is 61 mV greater than that (0.874 V) of the commercial Pt/C catalyst. In addition, all of them exhibit excellent stability, compared with commercial Pt/C catalysts. This synthetic strategy can be further extended to improve the different catalytic activities of small Au-based NPs by alloying surface engineering.