Pt‐Based Nanocrystal for Electrocatalytic Oxygen Reduction

Abstract

Currently, Pt-based electrocatalysts are adopted in the practical proton exchange membrane fuel cell (PEMFC), which converts the energy stored in hydrogen and oxygen into electrical power. However, the broad implementation of the PEMFC, like replacing the internal combustion engine in present automobile fleet, sets a requirement for less Pt loading compared to current devices. In principle, the requirement needs the Pt-based catalyst to be more active and stable. Two main strategies, engineering electronic (d-band) structure (including controlling surface facet, tuning surface composition, and engineering surface strain) and optimizing reactant adsorption sites are discussed and categorized based on the fundamental working principle. In addition, general routes for improving the electrochemical surface area, which improves activity normalized by the unit mass of precious group metal/platinum group metal, and stability of the electrocatalyst are also discussed. Furthermore, the recent progress of This article is protected by copyright. All rights reserved. 2full fuel cell tests of novel electrocatalysts is summarized. It is suggested that a better understanding of the reactant/intermediate adsorption, electron transfer, and desorption occurring at the electrolyte-electrode interface is necessary to fully comprehend these electrified surface reactions; and standardized MEA testing protocols should be practiced, and data with full parameters detailed, for reliable evaluation of catalyst functions in devices.

Strategies to Break the Scaling Relation toward Enhanced Oxygen Electrocatalysis

“…6,[13][14][15] A similar phenomenon also exists in the field of metal-air batteries, because the ORR and OER are again the key reactions during discharging/charging ( Figure 1C). 16 Adsorption-energy scaling relations are very useful tools for fast screening of catalysts, and various descriptors (such as DG(*O) À DG(*OH), 13 d-band center, [17][18][19] p-band center, 20 e g occupation, 21,22 [generalized] coordination number, [23][24][25] metal-oxygen covalency, [26][27][28] generalized electronegativity, 29 E 0 (M 3+ /M 2+ ), 30 surface distortion 31 and so on) have been proposed to correlate the adsorption-free energy of key intermediates and optimize the activity as close as possible to the apex of the volcano plot. 32 On the other hand, they can pose a limitation on the catalyst design with a minimum theoretical overpotential of about 0.37 V, even for the most reactive ORR and OER catalysts such as Pt-based alloys and IrO x (NiFeO x ).…”

Interface modulation of twinned PtFe nanoplates branched 3D architecture for oxygen reduction catalysis

“…Fig. 5c shows the mass activity of PtFe IL-skin-p-NDs/C reaches 3.15 A/mg Pt at 0.9 V versus RHE, exceeding the U.S. Department of Energy 2020 target (indicated by the dash line) [42] by almost 8 times, which is also the highest reported value among all the reported PtFe catalysts to the best of our knowledge (Table S1 online). The ORR polarization curves of PtFe IL-skin-p-NDs/C before and after 20,000 ADT cycles almost overlap each other (Fig.…”

“…In sharp contrast to the latter, the nanoplate component can well maintain the pristine morphology and twin boundary after high temperature annealing, and simultaneously generate the desired Pt-skin configuration and partially ordered structure. Impressively, by further integrating the Pt-skin nanoplates-branched PtFe nanodendrites with amino-functionalized ionic liquid, an unprecedented and stable mass activity of 3.15 A/mg Pt has been achieved in PtFe catalytic system towards ORR, almost 8 times higher than the U.S. Department of Energy 2020 target [42]. This study successfully breaks the activity ceiling of dendritic nanocatalysts and opens up new opportunities for endowing dendritic nanocrystals with superior catalytic performance.…”

H 2 ‐induced thermal treatment significantly influences the development of a high performance low‐platinum core‐shell PtNi/C alloyed oxygen reduction catalyst

“…[1][2][3][4] As an efficient energy conversion devices, the operating principle of PEMFC is typically made up of two fundamental electrochemical processes on each side of the polymer electrolyte membrane electrodes. 5,6 However, the oxygen reduction reaction (ORR) at cathode is more complicated and pivotal in achieving the better fuel cell performance, so ORR catalysts are decisive in the development and widespread commercialization of PEMFCs. [7][8][9] Fabricating the highly active, low-platinum and durable ORR catalyst is one of the most effective way for the improvement of fuel cells performance.…”