Strain and Surface Engineering of Multicomponent Metallic Nanomaterials with Unconventional Phases

Grain-Boundary-Rich RuO2 Porous Nanosheet for Efficient and Stable Acidic Water Oxidation

RuO2 has been considered as the most likely acidic oxygen evolution reaction (OER) catalyst to replace IrO2, but its performance, especially long-term stability under harsh acidic conditions, is still unacceptable. Here, we propose a grain boundary (GB) engineering strategy by fabricating the ultrathin porous RuO2 nanosheet with abundant of grain boundaries (GB-RuO2) as an efficient acid OER catalyst. The involvement of GB induces significant tensile stress and creates an unsaturated coordination environment, effectively optimizing the adsorption of intermediates and stabilizing active site structure during OER process. Notably, the GB-RuO2 not only exhibits a low overpotential (η10=187 mV) with an ultra-low Tafel slope (34.5 mV dec-1), but also steadily operates for over 550 h in 0.1 M HClO4. Quasi in situ/operando methods confirm that the improved stability is attributed to GB preventing Ru dissolution and greatly inhibiting the lattice oxygen oxidation mechanism (LOM). A proton exchange membrane water electrolysis (PEMWE) using the GB-RuO2 catalyst operates a low voltage of 1.669 V at 2 A cm-2 and operates stably for 100 h at 100 mA cm-2.

Controlled Synthesis of Unconventional Phase Alloy Nanobranches for Highly Selective Electrocatalytic Nitrite Reduction to Ammonia

The controlled synthesis of metal nanomaterials with unconventional phases is of significant importance to develop high-performance catalysts for various applications. However, it remains challenging to modulate the atomic arrangements of metal nanomaterials, especially the alloy nanostructures that involve different metals with distinct redox potentials. Here we report the general one-pot synthesis of IrNi, IrRhNi and IrFeNi alloy nanobranches with unconventional hexagonal close-packed (hcp) phase. Notably, the as-synthesized hcp IrNi nanobranches demonstrate excellent catalytic performance towards electrochemical nitrite reduction reaction (NO2RR), with superior NH3 Faradaic efficiency and yield rate of 98.2 % and 34.6 mg h-1 mgcat -1 (75.5 mg h-1 mgIr -1) at 0 and -0.1 V (vs reversible hydrogen electrode), respectively. Ex/in situ characterizations and theoretical calculations reveal that the Ir-Ni interactions within hcp IrNi alloy improve electron transfer to benefit both nitrite activation and active hydrogen generation, leading to a stronger reaction trend of NO2RR by greatly reducing energy barriers of rate-determining step.

Elucidating the Role of Reduction Kinetics in the Phase-Controlled Growth on Preformed Nanocrystal Seeds: A Case Study of Ru

This study demonstrates the crucial role of reduction kinetics in phase-controlled synthesis of noble-metal nanocrystals using Ru nanocrystals as a case study. We found that the reduction kinetics played a more important role than the templating effect from the preformed seed in dictating the crystal structure of the deposited overlayers despite their intertwined effects on successful epitaxial growth. By employing two different polyols, a series of Ru nanocrystals with tunable sizes of 3-7 nm and distinct patterns of crystal phase were synthesized by incorporating different types of Ru seeds. Notably, the use of ethylene glycol and triethylene glycol consistently resulted in the formation of Ru shell in natural hexagonal close-packed (hcp) and metastable face-centered cubic (fcc) phases, respectively, regardless of the size and phase of the seed. Quantitative measurements and theoretical calculations suggested that this trend was a manifestation of the different reduction kinetics associated with the precursor and the chosen polyol, which, in turn, affected the reduction pathway (solution versus surface) and packing sequence of the deposited Ru atoms. This work not only underscores the essential role of reduction kinetics in controlling the packing of atoms and thus the phase taken by Ru nanocrystals but also suggests a potential extension to other noble-metal systems.

Lattice engineering of noble metal-based nanomaterials via metal-nonmetal interactions for catalytic applications

Noble metal-based nanomaterials possess outstanding catalytic properties in various chemical reactions. However, the increasing cost of noble metals severely hinders their large-scale applications. A cost-effective strategy is incorporating noble metals with light nonmetal elements (e.g., H, B, C, N, P and S) to form noble metal-based nanocompounds, which can not only reduce the noble metal content, but also promote their catalytic performances by tuning their crystal lattices and introducing additional active sites. In this review, we present a concise overview of the recent advancements in the preparation and application of various kinds of noble metal-light nonmetal binary nanocompounds. Besides introducing synthetic strategies, we focus on the effects of introducing light nonmetal elements on the lattice structures of noble metals and highlight notable progress in the lattice strain engineering of representative core-shell nanostructures derived from these nanocompounds. In the meantime, the catalytic applications of the light element-incorporated noble metal-based nanomaterials are discussed. Finally, we discuss current challenges and future perspectives in the development of noble metal-nonmetal based nanomaterials.

Strain Engineering of Unconventional Crystal-Phase Noble Metal Nanocatalysts

The crystal phase, alongside the composition, morphology, architecture, facet, size, and dimensionality, has been recognized as a critical factor influencing the properties of noble metal nanomaterials in various applications. In particular, unconventional crystal phases can potentially enable fascinating properties in noble metal nanomaterials. Recent years have witnessed notable advances in the phase engineering of nanomaterials (PEN). Within the accessible strategies for phase engineering, the effect of strain cannot be ignored because strain can act not only as the driving force of phase transition but also as the origin of the diverse physicochemical properties of the unconventional crystal phase. In this review, we highlight the development of unconventional crystal-phase noble metal nanomaterials within strain engineering. We begin with a short introduction of the unconventional crystal phase and strain effect in noble metal nanomaterials. Next, the correlations of the structure and performance of strain-engineered unconventional crystal-phase noble metal nanomaterials in electrocatalysis are highlighted, as well as the phase transitions of noble metal nanomaterials induced by the strain effect. Lastly, the challenges and opportunities within this rapidly developing field (i.e., the strain engineering of unconventional crystal-phase noble metal nanocatalysts) are discussed.

FeCoCuMnRuB Nanobox with Dual Driving of High-Entropy and Electron-Trap Effects as the Efficient Electrocatalyst for Water Oxidation

High-entropy borides hold potential as electrocatalysts for water oxidation. However, the synthesis of the tailored nanostructures remains a challenge due to the thermodynamic immiscibility of polymetallic components. Herein, a FeCoCuMnRuB nanobox decorated with a nanosheet array was synthesized for the first time by a "coordination-etch-reduction" method. The FeCoCuMnRuB nanobox has various structural characteristics to express the catalytic performance; meanwhile, it combines the high-entropy effect of multiple components with the electron trap effect induced by electron-deficient B, synergistically regulating its electronic structure. As a result, FeCoCuMnRuB nanobox exhibits enhanced OER activity with a low overpotential (η10 = 233 mV), high TOF value (0.0539 s-1), small Tafel slope (61 mV/dec), and a satisfactory stability for 200 h, outperforming the high-entropy alloy and low-entropy borides. This work develops a high entropy and electron-deficient B-driven strategy for motivating the catalytic performance of water oxidation, which broadens the structural diversity and category of high-entropy materials.

Introduction to advances in multicomponent plasmonic hybrid nanoarchitectures for versatile applications

An introduction to the Nanoscale Advances themed collection on multicomponent plasmonic hybrid nanoarchitectures with precisely tailored properties for emerging applications, featuring burgeoning research on a variety of multifunctional plasmonic nanoparticles with synergistically reinforced properties.

Tailoring Local Chemical Ordering via Elemental Tuning in High-Entropy Alloys

Due to the large multi-elemental space desired for property screening and optimization, high-entropy alloys (HEAs) hold greater potential over conventional alloys for a range of applications, such as structural materials, energy conversion, and catalysis. However, the relationship between the HEA composition and its local structural/elemental configuration is not well understood, particularly in noble-metal-based HEA nanomaterials, hindering the design and development of nano-HEAs in energy conversion and catalysis applications. Herein, we determined precise atomic-level structural and elemental arrangements in model HEAs composed of RhPtPdFeCo and RuPtPdFeCo to unveil their local characteristics. Notably, by changing just one constituent element in the HEA (Rh to Ru), we found dramatic changes in the elemental arrangement from complete random mixing to a local single elemental ordering feature. Additionally, we demonstrate that the local ordering in RuPtPdFeCo can be further controlled by varying the Ru concentration, allowing us to toggle between local Ru clustering and distinct heterostructures in multicomponent systems. Overall, our study presents a practical approach for manipulating local atomic structures and elemental arrangements in noble-metal-based HEA systems, which could provide in-depth knowledge to mechanistically understand the functionality of noble-metal-based HEA nanomaterials in practical applications.