High‐Index Faceted PdPtCu Ultrathin Nanorings Enable Highly Active and Stable Oxygen Reduction Electrocatalysis

Abstract

Ultrathin nanosheet catalysts deliver great potential in catalyzing the oxygen reduction reaction (ORR), but encounter the ceiling of the surface atomic utilizations, thus presenting a challenge associated with further boosting catalytic activity. Herein, a kind of PdPtCu ultrathin nanorings with increased numbers of electrocatalytically active sites is reported, with the purpose of breaking the activity ceiling of conventional catalysts. The as‐made PdPtCu nanorings possess abundant high‐index facets at the edge of both the exterior and interior surfaces. An ultrahigh electrochemical active surface area of 92.2 m2 g–1PGM is achieved on this novel catalyst, much higher than that of the commercial Pt/C catalyst. The optimized Pd39Pt33Cu28/C shows a great enhanced ORR activity with a specific activity of 2.39 mA cm–2 and a mass activity of 1.97 A mg–1PGM at 0.9 V (versus RHE), as well as superior durability within 30 000 cycles. Density function theory calculations reveal that the high‐index facets and alloying Cu atoms can optimize the oxygen adsorption energy, explaining the enhanced ORR activity. Overcoming a key technical barrier in sub‐nanometer electrocatalysts, this work successfully introduces the hollow structures into the ultrathin nanosheets, heralding the exciting prospects of high‐performance ORR catalysts in fuel cells.

Two-dimensional copper based colloidal nanocrystals: synthesis and applications

“…35,62 Among the metallic Cu 2D NCs seeded growth materialised NCs with PdCu and PdPtCu compositions. 63 Apart from these, many other unconventional compositions such as Cu 3 P 1− x S x and CsCu 5 S 3 have also been achieved using colloidal methods. 64,65 All the compositional outcomes that are achieved using the colloidal approach are highlighted in Scheme 1b.…”

“…64 Alloyed Cu-based multimetallic NCs such as PtPdCu nanorings have also been synthesised via Cu 2+ introduction of the PtPd template. 63 The milestones achieved in terms of synthesis in this field are highlighted in Scheme 2.…”

“…For example, Li et al reported PdPtCu ultrathin nanorings using W(CO) 6 as a reductant. 63 Initially, Pd-rich ultrathin nanosheets were synthesized, and these nanosheets were alloyed with Pt to form PdPt nanosheets. Furthermore, PdPt nanosheets were employed as seeds for PdPtCu nanoring formation.…”

“…Owing to the unique characteristics related to their structural features, copper-based 2D NCs have received a lot of interest in plasmonics, heterogeneous catalysis, thermoelectrics and metal-ion batteries. 28,63,141,150,162,163 2D nanostructures outperform 0D and 1D nanomaterials in architectural modification, charge separation, light harvesting and tunability. 7,164 Extensive research has been done to develop effective catalysts with 2D nanomaterials, inspired by the unique optical, electronic properties and high surface area.…”

“…7,164 Extensive research has been done to develop effective catalysts with 2D nanomaterials, inspired by the unique optical, electronic properties and high surface area. 63,162,165 2D nanostructures with a high surface-area-to-volume ratio and a high density of exposed atoms on their surface hold great promise for enhancing plasmonic resonance and catalytic processes. With the variable valence states, high defect densities, and vast compositional ranges, these NCs have become an ideal choice for the domain of catalysis.…”