Wet-Chemical Synthesis of Concave Hexoctahedral Pd and Pd@Pt Nanocrystals for Methanol Electrooxidation.

Nanocrystals (NCs) exposed with high-index facets usually show enhanced electrocatalytic performances. However, it is a great challenge to persevere with high-index facets against their high surface energy during the synthesis. Herein, we successfully synthesize concave hexoctahedral (c-HOH) Pd NCs exposed with 48 high-index {741} facets using a facile one-pot wet-chemical protocol.

Breaking Surface Atomic Monogeneity of Rh P Nanocatalysts by Defect-Derived Phosphorus Vacancies for Efficient Alkaline Hydrogen Oxidation.

Breaking atomic monogeneity of catalyst surfaces is promising for constructing synergistic active centers to cope with complex multi-step catalytic reactions. Here, we report a defect-derived strategy for creating surface phosphorous vacancies (P-vacancies) on nanometric Rh P electrocatalysts toward drastically boosted electrocatalysis for alkaline hydrogen oxidation reaction (HOR). This strategy disrupts the monogeneity and atomic regularity of the thermodynamically stable P-terminated surfaces.

Two-dimensional template-directed synthesis of one-dimensional kink-rich PdPb nanowires for efficient oxygen reduction.

Developing facile synthetic strategies toward ultrafine one-dimensional (1D) nanowires (NWs) with rich catalytic hot spots is pivotal for exploring effective heterogeneous catalysts. Herein, we demonstrate a two-dimensional (2D) template-directed strategy for synthesizing 1D kink-rich PdPb NWs with abundant grain boundaries to serve as high-efficiency electrocatalysts toward oxygen reduction reaction (ORR). In this one-pot synthesis, ultrathin Pd nanosheets were initially generated, which then served as self-sacrificial 2D nano-templates.

Equilibrated PtIr/IrO Atomic Heterojunctions on Ultrafine 1D Nanowires Enable Superior Dual-Electrocatalysis for Overall Water Splitting.

Dual-active-sites atomically coupled on ultrafine 1D nanowires (NWs) can offer synergic atomic heterojunctions (AHJs) and high atomic-utilization toward multipurpose and superior catalysis. Here, ≈2-nm-thick PtIr/IrO hybrid NWs are elaborately synthesized with equilibrated Pt/IrO AHJs as high-efficiency bifunctional electrocatalysts for overall water splitting. Mechanism studies reveal the atomically coupled Pt-IrO dual-sites are favorable for facilitating water dissociation, alleviating the binding of H* on Pt sites and inversely regulating the *OH adsorption and oxidation on bridge Ir-Ir sites.

Concave nano-octahedral alloys: wet chemical synthesis of bimetallic Pt-Pd nanocrystals with high-index {} Facets.

Concave morphologies provide noble metal nanocrystals (NCs) with unique performances due to large specific surface areas, high curves, hot spots, and elevated energy facets. As a result, concave morphologies have attracted considerable attention in many areas. However, most NCs with concave shapes are currently made of a single metal, leaving plenty of room for easy wet chemical synthesis and structural analysis of unique concave structures, especially bimetallic compounds.

Amplified Interfacial Effect in an Atomically Dispersed RuO -on-Pd 2D Inverse Nanocatalyst for High-Performance Oxygen Reduction.

Atomically dispersed oxide-on-metal inverse nanocatalysts provide a blueprint to amplify the strong oxide-metal interactions for heterocatalysis but remain a grand challenge in fabrication. Here we report a 2D inverse nanocatalyst, RuO -on-Pd nanosheets, by in situ creating atomically dispersed RuO /Pd interfaces densely on ultrathin Pd nanosheets via a one-pot synthesis. The product displays unexpected performance toward the oxygen reduction reaction (ORR) in alkaline medium, which represents 8.

Structure-intensified PtCoRh spiral nanowires as highly active and durable electrocatalysts for methanol oxidation.

Platinum (Pt)-based nanocatalysts with a high density of surface atomic steps hold great prospects in electrocatalysis. However, the structural instability under harsh redox conditions is still a rigorous challenge. Here, we demonstrate that ternary PtCoRh alloyed spiral nanowires (SNWs), which have the advantages of one-dimensional nanowires, alloy synergy, surface atomic steps, and anti-corrosive Rh incorporation, can serve as active and robust MOR electrocatalysts in acidic media.

Kinetically Manipulating the Nucleus Attachment to Create Atypical Defective Rh-Pt Alloyed Nanostructures as Active Electrocatalysts.

Defective metal nanostructures have attracted great attention due to the striking catalytic behavior of the defect sites. Atypical metal nanocrystals generated from attached nuclei can accommodate abundant grain boundaries (GBs) and twin boundaries (TBs). However, the understanding of their growth-mechanism and precisely synthetic control over such defective nanocrystals are still scarce.

Edge Enrichment of Ultrathin 2D PdPtCu Trimetallic Nanostructures Effectuates Top-Ranked Ethanol Electrooxidation.

Atomic edge sites on two-dimensional (2D) nanomaterials display striking catalytic behavior, whereas edge engineering for 2D metal nanocatalysts remains an insurmountable challenge. Here we advance a one-pot synthesis of ultrathin 2D PdPtCu trimetallic nanosheets and nanorings with escalating low-coordinated edge proportions from 11.74% and 23.

One-pot synthesis of Pd@PtNi core-shell nanobranches with ultrathin PtNi{111} skins for efficient ethanol electrooxidation.

Coating an ultrathin platinum-rich skin on nanosubstrates made of other cheaper metals is an effective strategy for fabricating active electrocatalysts with low Pt-content. We developed a facile one-pot synthesis of Pd@Pt3Ni core-shell nanobranches with ultrathin Pt3Ni{111} skins that have active and durable catalytic performances for ethanol electrooxidation.

Shape-Controlled Synthesis of Colloidal Metal Nanocrystals by Replicating the Surface Atomic Structure on the Seed.

Controlling the surface structure of metal nanocrystals while maximizing the utilization efficiency of the atoms is a subject of great importance. An emerging strategy that has captured the attention of many research groups involves the conformal deposition of one metal as an ultrathin shell (typically 1-6 atomic layers) onto the surface of a seed made of another metal and covered by a set of well-defined facets. This approach forces the deposited metal to faithfully replicate the surface atomic structure of the seed while at the same time serving to minimize the usage of the deposited metal.

Ligand-Assisted, One-Pot Synthesis of Rh-on-Cu Nanoscale Sea Urchins with High-Density Interfaces for Boosting CO Oxidation.

Predictable synthesis of bimetallic nanocrystals with spatially controlled metal distributions offers a versatile route to the development of highly efficient nanocatalysts. Here we report a one-pot synthesis of super branched Rh-on-Cu nanoscale sea urchins (Rh-Cu NSUrs) with a high density of Cu-Rh interfaces by manipulating the ligand coordination chemistry. Structural analysis and UV-vis spectra reveal that ascorbic acid can serve as a Rh-selective coordination ligand in the nonaqueous synthesis to reverse the reduction potentials of Rh and Cu cations.

Well-faceted noble-metal nanocrystals with nonconvex polyhedral shapes.

Precise engineering of noble-metal nanocrystals (NCs) is not only an important fundamental research topic, but also has great realistic significance in improving their performances required by the poor reserve and high cost of noble metals. Well-faceted noble-metal NCs with nonconvex polyhedral shapes could be promising candidates to optimize their performance and thus minimize their usage, as they may integrate a well-defined surface structure and a large surface area together, enabling them to have outstanding performance and high efficiency of atomic utilization. Moreover, undesirable aggregation and ripening phenomena could be avoided.

Rational design and synthesis of excavated trioctahedral Au nanocrystals.

Excavated polyhedral nanostructures, possessing the features of high surface area and well-defined surface structure with a specific crystal facet and avoidance of aggregation, could be one of the best choices for the purpose of reducing consumption and improving performance of noble metals in many application fields. However, the formation of the excavated structures is thermodynamically unfavourable and its rational synthesis is far beyond our knowledge. In this work, taking overgrowth of Pd onto trioctahedral Au nanocrystals as a model, we present a deep insight study for synthesizing an excavated structure relying on the protection role of surfactants under suitable crystal growth kinetics.

Atomic layer-by-layer deposition of platinum on palladium octahedra for enhanced catalysts toward the oxygen reduction reaction.

We systematically evaluated two different approaches to the syntheses of Pd@PtnL (n = 2-5) core-shell octahedra. We initially prepared the core-shell octahedra using a polyol-based route by titrating a Pt(IV) precursor into the growth solution containing Pd octahedral seeds at 200 °C through the use of a syringe pump. The number of Pt atomic layers could be precisely controlled from two to five by increasing the volume of the precursor solution while fixing the amount of seeds.

Atomic layer-by-layer deposition of Pt on Pd nanocubes for catalysts with enhanced activity and durability toward oxygen reduction.

An effective strategy for reducing the Pt content while retaining the activity of a Pt-based catalyst is to deposit the Pt atoms as ultrathin skins of only a few atomic layers thick on nanoscale substrates made of another metal. During deposition, however, the Pt atoms often take an island growth mode because of a strong bonding between Pt atoms. Here we report a versatile route to the conformal deposition of Pt as uniform, ultrathin shells on Pd nanocubes in a solution phase.

Organic-inorganic interface-induced multi-fluorescence of MgO nanocrystal clusters and their applications in cellular imaging.

Surface functionalization of inorganic nanomaterials through chemical binding of organic ligands on the surface unsaturated atoms, forming unique organic-inorganic interfaces, is a powerful approach for creating special functions for inorganic nanomaterials. Herein, we report the synthesis of hierarchical MgO nanocrystal clusters (NCs) with an organic-inorganic interface induced multi-fluorescence and their application as new alternative labels for cellular imaging. The synthetic method was established by a dissolution and regrowth process with the assistance of carboxylic acid, in which the as-prepared MgO NCs were modified with carboxylic groups at the coordinatively unsaturated atoms of the surface.

Controlling the size and composition of nanosized Pt-Ni octahedra to optimize their catalytic activities toward the oxygen reduction reaction.

Electrocatalysts based on Pt-Ni alloys have received considerable interest in recent years owing to their remarkable activities toward the oxygen reduction reaction (ORR). Here, we report the synthesis of nanosized Pt-Ni octahedra with a range of controlled sizes and compositions in an effort to optimize their ORR activities. If we employed benzyl ether as a solvent for the synthesis, we could readily control the edge lengths of the Pt-Ni octahedra in the range of 6-12 nm and keep the Pt/Ni atomic ratio at around 2.

Synthesis of rhodium concave tetrahedrons by collectively manipulating the reduction kinetics, facet-selective capping, and surface diffusion.

This paper describes a facile synthesis of Rh tetrahedrons with concave side faces by collectively manipulating the reaction kinetics, facet-selective capping, and surface diffusion of atoms. Specifically, a combination of Na3RhCl6, triethylene glycol, l-ascorbic acid, and citric acid provides the right conditions for generating the concave tetrahedrons. After the formation of small Rh tetrahedral seeds through self-nucleation, the subsequently generated Rh atoms were selectively deposited onto the corner sites to generate Rh tetrapods.

Enhanced shape stability of Pd-Rh core-frame nanocubes at elevated temperature: in situ heating transmission electron microscopy.

Shape stability of Pd-Rh core-frame nanocubes was studied by in situ heating transmission electron microscopy. Pd-Rh nanocubes could maintain cubic shape at elevated temperature compared with pure Pd. The surface diffusion process of Rh onto {100} side surfaces is believed to postpone the degradation to higher temperature.

Confining the nucleation and overgrowth of Rh to the {111} facets of Pd nanocrystal seeds: the roles of capping agent and surface diffusion.

This article describes a systematic study of the spatially confined growth of Rh atoms on Pd nanocrystal seeds, with a focus on the blocking effect of a surface capping agent and the surface diffusion of adatoms. We initially used Pd cuboctahedrons as the seeds to illustrate the concept and to demonstrate the capabilities of our approach. Because the Pd{100} facets were selectively capped by a layer of chemisorbed Br(–) or I(–) ions, we were able to confine the nucleation and deposition of Rh atoms solely on the {111} facets of a Pd seed.

Synthesis and characterization of 9 nm Pt-Ni octahedra with a record high activity of 3.3 A/mg(Pt) for the oxygen reduction reaction.

Nanoscale Pt-Ni bimetallic octahedra with controlled sizes have been actively explored in recent years owning to their outstanding activity for the oxygen reduction reaction (ORR). Here we report the synthesis of uniform 9 nm Pt-Ni octahedra with the use of oleylamine and oleic acid as surfactants and W(CO)6 as a source of CO that can promote the formation of {111} facets in the presence of Ni. Through the introduction of benzyl ether as a solvent, the coverage of both surfactants on the surface of resultant Pt-Ni octahedra was significantly reduced while the octahedral shape was still attained.

Facile synthesis of Pd-Ir bimetallic octapods and nanocages through galvanic replacement and co-reduction, and their use for hydrazine decomposition.

This article describes a facile synthesis of Pd-Ir bimetallic nanostructures in the forms of core-shell octapods and alloyed nanocages. The success of this synthesis relies on the use of Pd nanocubes as the sacrificial templates and interplay of two different processes: the galvanic replacement between an Ir precursor and the Pd nanocubes and the co-reduction of Pd(2+) and Ir(3+) by ethylene glycol. The galvanic replacement played a dominant role in the initial stage, through which Pd atoms were dissolved from the side faces whereas Ir atoms were deposited at the corner sites to generate Pd-Ir core-shell octapods.

Citrate-free synthesis of silver nanoplates and the mechanistic study.

We report a citrate-free synthesis of Ag nanoplates with an edge length of 50 nm that involved the reduction of AgNO3 by poly(vinyl pyrrolidone) (PVP) in ethanol at 80 °C under a solvothermal condition. Within a period of 4 h, greater than 99% of the initially added AgNO3 could be converted into Ag nanoplates with excellent stability. To understand this remarkably simple and efficient process, we systematically investigated the roles played by various reaction parameters, which include the type of precursor, reducing powers of PVP and ethanol, molar ratio of PVP to AgNO3, solvent, involvement of O2, and effects of pressure and temperature.