Simultaneously engineering the size and surface crystal facets of bimetallic core–shell nanocrystals offers an effective route to not only reduce the extravagance of innermost core metal and maximize the utilization efficiency of shell atoms but also strengthen the core-to-shell interaction via ligand and/or strain effects. Herein, we systematically study the architecture transition and crystal facet engineering at the atomic level on the surface of sub-5 nm Pd(111) tetrahedrons (Ths), aimed at embodying how the variations in the local facet and shape of a sub-10 nm core–shell structure affect its surface geometrical properties and electronic structures. Specifically, surface atomic replication is predominant when the shell metal deposits less than five atomic layers, thus forming a series of Pd@M (M = Pt, Ru, and Rh) core–shell Ths enclosed by (111) facets (∼6.8 nm), while over five atomic layers, spontaneous facets tropism of each metal is predominant, where Pt atoms still follow fcc-(111) packing, Ru atoms select hcp-phase stacking, and Rh atoms choose fcc-(100) crystallization, respectively. In particular, Pt atoms take a seamless geometrical transformation from Pd@Pt Ths into Pd@Pt truncated octahedrons (TOhs, ∼7.6 nm). As a proof-of-concept application, such sub-10 nm core–shell architectures with Pt skin show a component-dependent relationship toward oxygen reduction reaction (ORR), where the catalytic activity follows the order of Pd@Pt(111) TOhs (E 1/2 = 0.916 V, 1.632 A mgPt –1) > Pd@Pt(111) Ths > Pt black. Meanwhile the Ru skin show a facet-dependent relationship toward acidic hydrogen evolution reaction (HER) where the catalytic activity follows the order of Pd@Ru(111) Ths > Pd@Ru(hcp) Ths > Pd Ths.
It remains a grand challenge to command the island growth mode because a conformal growth is theoretically favorable in which the lattice mismatch between overlayer and substrate is negligible. Herein,...
The surface hydroxyl groups of NixCu1−x(OH)2 play a crucial role in governing their conversion efficiency into NixCu1−xOx(OH)2−x during the electro‐chemical pre‐activation process, thus affecting the integral ammonia oxidation reaction (AOR) reactivity. Herein, the rational design of hierarchical porous NiCu double hydroxide nanotyres (NiCu DHTs) was reported for the first time by considering hydroxyl‐rich interfaces to promote pre‐activation efficiency and intrinsic structural superiority (i.e., annulus, porosity) to accelerate AOR kinetics. A systematic investigation of the structure–function relationship was conducted by manipulating a series of NiCu DHs with tunable intercalations and morphologies. Remarkably, the NiCu DHTs exhibit superior AOR activity (onset potential of 1.31 V with 7.52 mA cm−2 at 1.5 V) and high ammonia sensitivity (detection limit of 9 μm), manifesting one of the best non‐noble metal AOR electrocatalysts and electro‐analytical electrodetectors. This work deepens the understanding of the crucial role of surface hydroxyl groups on determining the catalytic performance in alkaline medium.
further resolved into multistep intermediates adsorption/desorption subsets with relatively high energy barrier, thereby demanding structure-customized electrocatalysts to achieve optimal reaction pathways with neither too strong nor too weak binding toward key intermediates (Sabatier principle). [2] Alternatively, ternary metal catalysts (i.e., alloys, heterojunctions, multishells) [3] provide a shortcut to broaden the tunability in adsorption position and strength for a variety of reaction intermediates. In comparison with mono/binary metal catalysts, they are more promising for achieving multifunctionality and generating flexible synergetic interactions. [4] One side, the combination of three classes of metal species with disparate inherent activity provides tri-directional catalytic pathways for competitive adsorption. [5] Each class of metal could serve as host, manifesting the underlying trifunctionality. Other side, multiple hetero geneous metal interfaces could reciprocally tailor the electronic property of each metal species, thus breaking through the limitations in activity and selectivity for both the host and guest metals. [6] Downscaling the size of metal catalysts into single atom level has been admitted as powerful to achieve maximum metal utilization together with unique size quantum effects, such as metal-nitrogen single-atoms (SAs) that mimic the structure of bioporphyrins. [7] However, when it comes to ternary metal catalysts, there still remains grand challenge to simultaneously downscale all three metal species into single-atom level, due to the intractableness in synthesis, yield, and functional study. As illustrated in Figure 1, first, the synthesis of metallic ternary atoms (TAs) could learn from dual atoms (DAs), which normally involve the co-pyrolysis of either metal dimers or two metal precursors stabilized by organic ligands. [8] However, generalized to TAs, stable heterometal trimers with exact configurations are hard to be fabricated. Besides, co-pyrolysis of ligands-stabilized three metal precursors will inevitably form the coexisted TAs, DAs, and SAs due to the lack of effective separation strategy, which are hard to be distinguished and purified. Second, the metal loading of SAs is often limited to avoid aggregation (as low as 1-2 wt%). [9] Generalized to TAs, merely dividing the dosage of metal precursors into trisection with different kinds will not increase the metal loading. Either, Ternary metal catalysts hold great promise in complementary functionality and synergistic interplay, which are promising for combined reactions involving multi-intermediates. However, simultaneously downscaling all three metal species into single-atom level still remains challenge. Herein, a universal metal encapsulation-segregation-overlay strategy is designed to realize the fabrication of heterogeneous M 1 N 4 -C-M 2 N 4 -C-M 3 N 4 ternary singleatoms (TSAs)-based catalysts, with well-defined configuration and threefold enhancement of single-atom loading (IrPtCu TSAs, up to 21.24 wt%). Tak...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.