Synergistically Enhanced Oxygen Reduction Electrocatalysis by Subsurface Atoms in Ternary PdCuNi Alloy Catalysts

Abstract

For Pd-based alloy catalysts, the selection of metallic alloying elements and the construction of composition-gradient surface and subsurface layers are critical in achieving superior electrocatalytic activities in, e.g., the oxygen reduction reaction (ORR). Based on the Pd-containing alloy, highly monodispersed PdCuNi ternary alloy nanocrystals are prepared through a wet-chemical approach, and a solution-based oxidative surface treatment protocol is utilized to activate the surface of the nanocrystals. A drastically enhanced ORR activity can be achieved by removing the surface Ni and Cu atoms through the surface treatment protocol. The treated catalyst demonstrates a mass activity of 0.45 A mg Pd −1 in alkaline medium, 5 and 2.4 times those of commercial Pt/C and Pd/C, respectively. The first-principle calculation result suggests the critical roles of the coexistence of Ni and Cu atoms and their synergistic interaction beneath the outmost pure Pd layer in optimizing the oxygen binding energy for ORR. The calculation also suggests that the optimal binding energy of oxygen requires an appropriate Ni/Cu ratio in the subsurface layer. This work demonstrates a class of high-performance Pt-free ternary alloy ORR catalysts and may provide a general guideline for the structural design of Pd-based ternary alloy catalysts.

Tungsten as “Adhesive” in Pt2CuW0.25 Ternary Alloy for Highly Durable Oxygen Reduction Electrocatalysis

“…Pseudopotentials implemented in the projector augmented-wave method were used to simulate the core electrons. [45] The lattice constant of the alloy was found to be 1.36% smaller than Pt (3.979 Å), which was consistent with previous studies. All structures were relaxed using a limited memory Broyden-Fletcher-Goldfarb-Shanno [44] algorithm until forces on all atoms are less than 0.03 eV Å −1 .…”

Fast Cryomediated Dynamic Equilibrium Hydrolysates towards Grain Boundary-Enriched Platinum Scaffolds for Efficient Methanol Oxidation

“…As revealed in Figure 4(a) and Figures S24 and S25, in the case of 3D GB-Pt scaffolds, there are three prominent XRD peaks at 39.8°, 46.2°, and 67.7°, corresponding to the (111), (200), and (220) planes of face-centered-cubic (fcc) platinum (JCPDS no. 87-0647) [37], respectively, in good accordance with the above HRTEM and SAED analyses. The XPS survey demonstrates that there are only two main species of Pt and O detected in our 3D GB-Pt scaffolds, without other impurities (Figure 4(b) and Figures S26 and S27).…”

Regulating the Catalytic Dynamics Through a Crystal Structure Modulation of Bimetallic Catalyst

“…The bcc PdCu has generally been synthesized by annealing its fcc analogue or by the seeded growth method finally making its crystallite size larger than 20 nm . In spite of relatively larger particle size with lower reactive surface area, bcc PdCu exhibits higher catalytic activity or selectivity for various reactions compared to its fcc analogue because the surface Pd of bcc PdCu may serve as an electron‐rich active site thanks to a charge redistribution between Pd and Cu . However, two polymorphs (bcc and fcc) with the same particles size and similar microstructures need to be comparatively studied to figure out how the polymorphic change between fcc and bcc regulates the reaction dynamics during their ORR/OER.…”