Preparation of fcc‐2H‐fcc Heterophase Pd@Ir Nanostructures for High‐Performance Electrochemical Hydrogen Evolution

Abstract

nanomaterials (PEN), [2] tuning the crystal phase of noble-metal heterostructures paves a new avenue to efficiently tailor their properties and functions. In particular, noble-metal heterostructures with unconventional heterophases, which are composed of two or more phases, can show great application potentials owing to the presence of phase boundaries and the synergistic effect between different phases. [1f,2a,3] Seeded epitaxial growth represents an efficient approach to prepare heterophase noble-metal heterostructures with desired compositions and morphologies. For instance, the 4H/face-centered cubic (fcc) heterophase Au@Pd core-shell nanorods [3a] and 4H/fcc heterophase Au-Ru hybrid nanostructures [1f ] with random 4H and fcc phase distributions were obtained by using the pre-synthesized 4H/fcc Au nanomaterials as templates, which exhibited excellent catalytic performance towards the electrochemical ethanol oxidation reaction and hydrogen evolution reaction (HER), respectively. However, it still remains challenging to rationally design and synthesize heterophase noblemetal nanostructures with well-controlled phase distribution. Very recently, our group reported the phase-selective epitaxial growth of 2H-and fcc-Au nanostructures on unconventional 2H-Pd seeds to prepare the fcc-2H-fcc heterophase Pd@Au core-shell nanorods for highly efficient electrocatalytic carbon dioxide (CO 2 ) reduction. [3b] Such unique epitaxial growth route could open a new gateway towards the With the development of phase engineering of nanomaterials (PEN), construction of noble-metal heterostructures with unconventional crystal phases, including heterophases, has been proposed as an attractive approach toward the rational design of highly efficient catalysts. However, it still remains challenging to realize the controlled preparation of such unconventional-phase noble-metal heterostructures and explore their crystal-phase-dependent applications. Here, various Pd@Ir core-shell nanostructures are synthesized with unconventional fcc-2H-fcc heterophase (2H: hexagonal close-packed; fcc: face-centered cubic) through a wet-chemical seeded method. As a result, heterophase Pd 66 @Ir 34 nanoparticles, Pd 45 @Ir 55 multibranched nanodendrites, and Pd 68 @Ir 22 Co 10 trimetallic nanoparticles are obtained via the phaseselective epitaxial growth of fcc-2H-fcc-heterophase Ir-based nanostructures on 2H-Pd seeds. Importantly, the heterophase Pd 45 @Ir 55 nanodendrites exhibit excellent catalytic performance toward electrochemical hydrogen evolution reaction (HER) under acidic conditions. An overpotential of only 11.0 mV is required to achieve a current density of 10 mA cm −2 on Pd 45 @Ir 55 nanodendrites, which is lower than those of the conventional fcc-Pd 47 @Ir 53 counterparts, commercial Ir/C and Pt/C. This work not only demonstrates an appealing route to synthesize novel heterophase nanomaterials for promising applications in the emerging field of PEN, but also highlights the significant role of the crystal phase in determining their cata...

Amorphous-crystalline PdRu bimetallene for efficient hydrogen evolution electrocatalysis

“…Hydrogen, as a renewable and sustainable clean energy source, has attracted much attention for replacing traditional fuel cells. 1–3 Electrochemical water splitting is considered as one of the economic and convenient strategies to produce hydrogen. 4–6 However, this method suffers from high operation voltage due to slow reaction kinetics, so it is necessary to enhance the reaction rate and improve the catalytic activity for the hydrogen evolution reaction (HER).…”

2D/0D hierarchical heterostructures prepared via facet‐selective epitaxial growth of triangular Rh nanoplates on 2H‐Pd nanoparticles

“…Noble metal epitaxial heterostructures have drawn tremendous attention due to their unique physicochemical properties and diverse promising applications, 1–4 especially in catalysis 5–9 . Substantial efforts have been devoted in the past decades to the rational structural regulation (e.g., composition, morphology, and dimensionality) of noble metal epitaxial heterostructures, in order to efficiently modulate their functions 2,10–14 . In particular, constructing hierarchical heterostructures via the epitaxial growth of low‐dimensional nanomaterials, such as one‐dimensional (1D) nanorods and two‐dimensional (2D) nanosheets/nanoplates, on the surfaces of seeded/templated nanomaterials with different dimensions has been demonstrated as an appealing strategy to enhance the performance in various applications, benefiting from the presence of low‐dimensional grown nanostructures and the synergistic effect between different components 14,15–20 .…”

“…Seeded/templated epitaxial growth has been proved to be one of the most powerful approaches to prepare noble metal heterostructures with desired composition, morphology, and dimensionality 10,14,21 . As an emerging strategy, phase engineering of nanomaterials 12,22–24 offers new opportunities to the construction of noble metal hierarchical heterostructures through tuning the crystal phase of seeds/templates in the epitaxial routes.…”

“…[5][6][7][8][9] Substantial efforts have been devoted in the past decades to the rational structural regulation (e.g., composition, morphology, and dimensionality) of noble metal epitaxial heterostructures, in order to efficiently modulate their functions. 2,[10][11][12][13][14] In particular, constructing hierarchical heterostructures via the epitaxial growth of low-dimensional nanomaterials, such as one-dimensional (1D) nanorods and two-dimensional (2D) nanosheets/nanoplates, on the surfaces of seeded/templated nanomaterials with different dimensions has been demonstrated as an appealing strategy to enhance the performance in various applications, benefiting from the presence of low-dimensional grown nanostructures and the synergistic effect between different components. 14,[15][16][17][18][19][20] However, it still remains a challenge to achieve the controlled preparation of noble metal heterostructures with well-defined hierarchical architectures.…”

“…Seeded/templated epitaxial growth has been proved to be one of the most powerful approaches to prepare noble metal heterostructures with desired composition, morphology, and dimensionality. 10,14,21 As an emerging strategy, phase engineering of nanomaterials 12,[22][23][24] offers new opportunities to the construction of noble metal hierarchical heterostructures through tuning the crystal phase of seeds/templates in the epitaxial routes. For instance, via the selective epitaxial growth of 1D Ru nanorods on the regions with unconventional 4H phase and face-centered cubic (fcc)-twinned boundaries in 1D 4H/fcc Au nanowires, the 1D/1D Ru-Au hierarchical heterostructures were obtained, which exhibited superior electrocatalytic activity in hydrogen evolution reaction (HER) in alkaline media.…”