High-Performance Nitrogen-Doped Intermetallic PtNi Catalyst for the Oxygen Reduction Reaction

Abstract

PtM (M = transition metals) nanomaterials have been recognized as promising catalysts for the oxygen reduction reaction (ORR) in fuel cells, with a much higher performance than pure Pt. However, the insufficient durability issue of PtM is often raised because of the fast dissolution of M in acid, impeding their commercialization. Herein, we report on a Ketjenblack (KB)-supported, nitrogen (N)-doped intermetallic PtNiN (Int-PtNiN/KB) catalyst that exhibits remarkably enhanced ORR activity and stability in an acidic electrolyte, superior to those of disordered PtNi/KB, disordered PtNiN/KB, and commercial Pt/C. The experimental results show that Int-PtNiN/KB has a distinctive ordering structure of alternating Ni4–N and Pt planes; we attribute the origin of the superior stability of this catalyst to the combined effect of the Ni4–N formation and the unique intermetallic structure, which effectively precludes Ni dissolution from the core. The density functional theory calculations suggest that the tensile strain introduced by the formation of an intermetallic phase and N-doping optimizes the binding of oxygenated species on the Pt surface and enable highly efficient electron transfer, leading to the enhanced ORR performance. This study offers an appropriate route for further enhancing both the activity and durability of PtM catalysts through a facile synthesis method by annealing in an NH3 gas under appropriate conditions.

Bimetallic Nanocrystals: Structure, Controllable Synthesis and Applications in Catalysis, Energy and Sensing

“…PtPd and PtRu catalysts with different shapes and structure have been proved to be effective catalysts for MOR, because Pd and Ru can change the electronic structure of Pt [ 15 , 39 , 155 , 156 ]. In addition, PdPt nanocrystals also exhibited facet and composition-dependent catalytic activity for MOR.…”

“…Many works in the literature have proved that PtNi catalyst exhibited much higher catalytic performance than pure Pt for the oxygen reduction reaction (ORR) in fuel cells. For example, Zhao and co-workers reported that intermetallic PtNi catalyst exhibited remarkably enhanced ORR activity in comparison to the disordered PtNi and commercial Pt/C, and the durability also was improved by N doping [15]. Figure 1.…”

Dopants in the Design of Noble Metal Nanoparticle Electrocatalysts and their Effect on Surface Energy and Coordination Chemistry at the Nanocrystal Surface

“…Zhao et al reported an N-doped intermetallic L1 0 -PtNi catalyst, where the N atoms are located at the interstitial site in the L1 0 -PtNi lattice (Figure 12a-d). [89] Through PXRD and in situ EXAFS analyses, it was demonstrated that the N atoms were located at the interstitial sites in the L1 0 -PtNi lattice, forming alternating atomic layers of a Ni 4 -N moiety and Pt along the c-axis ([001] direction). The intermetallic N-doped PtNi (Int-PtNiN/KB) catalyst exhibited a mass activity of 1.83 A mg Pt -1 at 0.9 V RHE and maintained 72.7% of its initial mass activity after 30 000 cycles of ADT (Figure 12e,f).…”

“…Reproduced with permission. [89] Copyright 2020, American Chemical Society. g-i) In situ S-doping in IrO x nanocage (ICS NC).…”

“…e) ORR polarization curves of the catalysts in O 2 -saturated 0.1 m HClO 4. f) Comparison of ORR mass activities of the catalysts at 0.9 V RHE before and after 30 000 cycles of ADT. Reproduced with permission [89]. Copyright 2020, American Chemical Society.…”