L1₂ Atomic Ordered Substrate Enhanced Pt-Skin Cu₃Pt Catalyst for Efficient Oxygen Reduction Reaction

Abstract

Constructing Pt skin on intermetallics has been confirmed as an efficient strategy to boost oxygen reduction reaction (ORR) kinetics. However, there still lacks a systematic study on revealing the influence of low-Pt-content intermetallic substrates (L12-PtM3). In this paper, Pt skin-encapsulated low-Pt-mole-fraction L12 Cu3Pt has been constructed (denoted as Pt-o-Cu3Pt/C) and compared with its disordered analogue (denoted as Pt-d-Cu3Pt/C). The L12 substrate shows a contracted lattice structure and provides Pt-o-Cu3Pt/C with an excellent specific activity of 1.73 mA cm–2, which is 1.4- and 8.4-fold higher than that of Pt-d-Cu3Pt/C and commercial Pt/C, respectively. Density functional theory calculations reveal that this superior performance is attributed to the more favorable oxygen adsorption energy of surface Pt atoms. Furthermore, the lower formation energy of L12 Cu3Pt combined with the enhanced antioxygenation of Pt provide Pt-o-Cu3Pt/C with a superior durability, showing only a 12.5% loss in mass activity after 5000 potential cycles. Therefore, it is suggested that L12 atomic ordered structure with a low Pt fraction is a promising substrate for building high-performance Pt-skin catalysts for ORR.

Sub‐6 nm Fully Ordered L10‐Pt–Ni–Co Nanoparticles Enhance Oxygen Reduction via Co Doping Induced Ferromagnetism Enhancement and Optimized Surface Strain

“…Analysis of Tafel plots indicate that all the samples display Tafel slopes of ~60 mV dec -1 at low overpotential region and ~120 mV dec -1 at higher one (Figure S8), suggesting identical ORR rate-determining steps (RDS) for all three catalysts. [19] The mass and specific activities of the studied catalysts at 0.9 V are calculated and listed in Figure 2c 9.5 nm PtNi octahedra/C --3.14 1.45 [32] PtNi core-shell NP/C 0.905 1.65 0.86 [31] Ga-doped Pt-Ni octahedra/C --2.53 1.24 [46] PtNi nano-octahedra/C 0.92 3.8 1.65 [36] Fully ordered L1 0 -FePt/C 0.958 3.16 0.69 [19] 8.9 nm L1 0 -CoPt/C 0.967 8.26 2.26 [25] 3.6 nm L1 0 -FePt/C 0.893 0.37 1.1 [47] 8 nm L1 0 -FePt/Pt/C 0.945 --0.7 [48] PtPb/Pt core/shell nanoplate/C --7.8 4.3 [28] Ordered Fe 3 Pt/Ti 0.5 Cr 0.5 N 0.92 1.28 0.57 [49] 3 nm AuCu 3 /C (0.1 M KOH) 0.82 --0.523 (at 0.8 V) [50] L1 2 -Cu 3 Pt/C 0.872 1.73 0.64 [51] Ordered Pt 3 Co/C 0.945 1.1 0.52 and Co could all be clearly detected in the NP. Noteworthy, a thin Pt layer of ~0.5 nm (Pt-skin) is observed due to the surface dealloying in acid (Figure 3c), which proves the formation of core/shell Pt-Ni-Co/Pt structure with ordered PtNi 0.8 Co 0.2 core and ~2 atomic layers of Pt shell.…”

Atomistic Imaging of Competition between Surface Diffusion and Phase Transition during the Intermetallic Formation of Faceted Particles

“…Nanoscale metallurgy, involving the liquidation, surface segregation, phase transition, and diffusion, is attracting more and more attention, because it is generally applied in the rational design and preparation of metallic-based nanocatalysts, − which are widely used in various electrochemical applications including oxygen reduction reaction (ORR), − oxygen evolution reaction, hydrogen oxidation reaction, and hydrogen evolution reaction . The aforementioned metallurgical behaviors have been extensively discussed for bulk materials in the past hundred years.…”

“…Interestingly, the surface optimization of nanocatalysts and well-defined stoichiometric intermetallics are presently attracting considerable research attention because of their special and excellent performance. ,,− The ORR activity of Pt 3 Ni icosahedral NPs stretching 20 tetrahedrons is 9 times higher than the commercial Pt/C catalyst. , It was reported the ordered intermetallic phase had improved the durability and activity of electrocatalysts compared with random alloys. ,,,, If the optimized facet intermetallic NPs can be prepared, then both of high electrocatalytic activity and good durability will be achieved. Indeed, the formation of intermetallics is achieved through thermal annealing above the eutectic point, which has been considered as one of the promising strategies.…”

“…35,36 It was reported the ordered intermetallic phase had improved the durability and activity of electrocatalysts compared with random alloys. 7,8,10,12,13 If the optimized facet intermetallic NPs can be prepared, then both of high electrocatalytic activity and good durability will be achieved. Indeed, the formation of intermetallics is achieved through thermal annealing above the eutectic point, which has been considered as one of the promising strategies.…”

Intermetallic Compounds: Liquid‐Phase Synthesis and Electrocatalytic Applications

“…In a work reported by Li et al, L 12 PtCu 3 @Pt was prepared and presents 8.4-time higher ORR specific activity than that of commercial Pt/C in 0.1 M HClO 4 . [45] By employing an electrostatic adsorption method, Yang and co-workers successfully anchored the metal cations onto supports and generated ultra-fine metal nanoparticles. In this methodology, the surface charge of the support can be easily tuned to positive or negative by adjusting the pH below or above its point of zero charge.…”