A unique platinum-graphene hybrid structure for high activity and durability in oxygen reduction reaction

Abstract

It remains a grand challenge to achieve both high activity and durability in Pt electrocatalysts for oxygen reduction reaction (ORR) in fuel cells. Here we develop a class of Pt highly concave cubic (HCC) nanocrystals, which are enriched with high-index facets, to enable high ORR activity. The durability of HCC nanocrystals can be significantly improved via assembly with graphene. Meanwhile, the unique hybrid structure displays further enhanced specific activity, which is 7-fold greater than the state-of-the-art Pt/C catalysts. Strikingly, it exhibits impressive performance in terms of half-wave potential (E1/2). The E1/2 of 0.967 V at the Pt loading as low as 46 μg cm−2, which stands as 63 mV higher than that of the Pt/C catalysts, is slightly superior to the record observed for the most active porous Pt-Ni catalyst in literature. This work paves the way to designing high-performance electrocatalysts by modulating their surface and interface with loading substrates.

Surface Polarization Matters: Enhancing the Hydrogen‐Evolution Reaction by Shrinking Pt Shells in Pt–Pd–Graphene Stack Structures

“…In our measurements, the rGO promotes the HER performance regardless of whether Pd or Pt is supported (Figure S4), as it can help prevent the aggregation of metal nanocrystals and provide interconnected and resistance-less network for efficient catalyst-electrode electron transfer. [13][14][15] In our stack structures, both the Pt-Pd surface polarization and rGO supports make important contributions to improving the HER performance.…”

“…[10] To tailor the Pt surface charge, we thus decided to take advantage of surface polarization, an effect that has been occasionally demonstrated for tuning catalysis. [13][14][15] Our Pt-Pd-rGO nanostructures are synthesized by a twostep process. [11,12] Herein, we report that the surface polarization enabled by the difference in the work function between Pt and Pd can boost the HER performance of Pt surface, based on a Pt-Pd-rGO (reduced graphene oxide) stack structure.…”

Platinum Multicubes Prepared by Ni2+‐Mediated Shape Evolution Exhibit High Electrocatalytic Activity for Oxygen Reduction

“…[9,10] Nevertheless,the interlaced (111)-(100) Pt surface at the nanoscale is found to help enhance the ORR activity, most likely because of as ynergetic effect between different facets. [12][13][14][15][16][17] Despite the common perception of superior ORR activities for Pt high-index facets relative to {100} facets,itremains an open question as to whether it is feasible to achieve high ORR performance on Pt nanocrystals having al arge {100} surface coverage.H erein, we demonstrate the synthesis of an ovel Pt-branched structure,m ulticube,w hose surface is mostly enclosed by {100} facets but contains asmall portion of high-index facets at the junction area between the adjacent cubic components.Such aunique structure exhibits strikingly high ORR performance in terms of activity (E 1/2 and current density) and durability,a nd nearly achieves the activity reported for Pt nanocrystals enriched with as tepped surface. [9][10][11] Fort his reason, tremendous efforts have been made to construct high-index facets on Pt nanocrystals for ORR studies.…”

Some recent developments in surface and interface design for photocatalytic and electrocatalytic hybrid structures

“…29 To design Pt surface structure toward high electrocatalytic activities, the study starts with the performance comparison of Pt nanocrystals 60 with different numbers of branches. Given the difficulty of surface design in hybrid structures -such a complex system with multiple components, we initiate surface catalytic research with single-component catalysts in certain cases.…”

“…22,41 It turns out that octopods exhibit superior catalytic performance to their counterparts (i.e., hexapods, tetrapods and tripods), mainly attributed to the high densities of stepped surface atoms on {311} high-index exposed facets (Fig. 29 Both the catalytic activity and stability of the Pt HCCs The design approach to Pt HCCs-rGO hybrid structures is a straightforward one in which the rGO only serves as a support for performance enhancement and does not participate in the formation of catalytic component (i.e., Pt in this case). The active surface areas have been tuned from 65 0.39 to 1.32 cm 2 by increasing the numbers of branches.…”