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Single-atom catalysts (SACs) featuring the complete atomic utilization of metal, high-efficient catalytic activity, superior selectivity, and excellent stability have been emerged as a frontier in the catalytic field. Recently, increasing interests have been drawn to apply SACs in biomedical fields for enzyme-mimic catalysis and disease therapy. To fulfill the demand of precision and personalized medicine, precisely engineering the structure and active site toward atomic levels is a trend for nanomedicines, promoting the evolution of metal-based biomedical nanomaterials, particularly biocatalytic nanomaterials, from nanoparticles to clusters and now to SACs. This review outlines the syntheses, characterizations, and catalytic mechanisms of metal clusters and SACs, with a focus on their biomedical applications including biosensing, antibacterial therapy, and cancer therapy, as well as an emphasis on their in vivo biological safeties. Challenges and future perspectives are ultimately prospected for SACs in diverse biomedical applications.

Dual-atom catalysts (DACs) are an important branch of single-atom catalysts (SACs), in which the former can effectively break the dilemma faced by the traditional SACs. The synergetic effects between bimetallic atoms provide many active sites, promising to improve catalytic performance and even catalyze more complex reactions. This paper reviews the recent research progresses of two kinds of DACs, including homonuclear and heteronuclear DACs, and their applications in oxygen reduction, carbon dioxide reduction, hydrogen evolution, oxygen evolution, Zn-air batteries, tandem catalytic reactions, and so on. In addition, in order to promote the further development of DACs, the challenges and perspectives of DACs are put forward.

Lattice-mismatch-directed hybrid metal@semiconductor core–shell nanocrystals with extended scope of diversity in composition and morphologies are critical to create more function integrations and applications. The case of metal@telluride hetero-nanostructures are more typical due to the electronegativity and electron affinity of tellurium, which are impediment of the telluride shell synthesis in the aqueous phase. Herein, we take advantage of the aqueous cation exchange (ACE) synthetic strategy, have synthesized Au@PbTe core–shell nanocrystals with engineering of amorphous/crystalline phase and shape evolution facilely. By controlling the kinetics of the ACE-enabled hydrothermal CE strategy and the starting phase/composition of Au@Ag2Te nanostructures, we also achieved core–shell to yolk–shell evolution with different Au core sizes and hollow PbTe shells. These plasmonic core–shell nanostructures with a suitable telluride shell thickness demonstrated potential applications in surface enhanced Raman scattering.

Efficient utilization of quantum dots (QDs) in a bulk-scale matrix with good enough performance but small quantity is important in real-world industrial applications. Considering the traditional problems of QDs (such as self-absorption, drastic agglomeration, and oxidation), here we realize the stable dispersion of highly luminescent QDs in a polymer matrix and their versatile 3D printing framework superstructures. Taking the example of doped QDs and perovskite QDs, we disperse them in a polymer gel with optimal viscosity and uniform dispersion. Then, by the direct-ink-writing (DIW) 3D printing method, the QD polymer gel could be printed into bulk-scale 1D, 2D, and hierarchical superstructures. The intrinsic polymer characters could be effectively maintained. The photoluminescence of QDs in solid polymer superstructures is stable enough for 2 years without much loss in their performance. The flexibility, good luminescent solar concentrator (LSC) properties, and their designable PMMA and PDMS polymer superstructures confirmed their promising applications in optical devices, biological imaging, and novel information treatment.

We successfully fabricate a novel concave nanostructure that is composed of atomically dispersed Ru atoms in Pt3Sn nanoconcaves (Ru-Pt3Sn NCs), which shows enhanced performance in methanol electroxidation compared to commercial Pt/C. This could be ascribed to the stable intermetallic structure and active surface structure, as well as the synergy among Pt, Sn and Ru.

Supported atomic clusters with uniform metal sites and definite low-nuclearity are intermediate states between single-atom catalysts (SACs) and nanoparticles in size. Benefiting from the presence of metal–metal bonds, supported atomic clusters can trigger synergistic effects among every metal atom, which contributes to achieving unique catalytic properties different from SACs and nanoparticles. However, the scalable and precise synthesis and atomic-level insights into the structure–properties relationship of supported atomic clusters is a great challenge. This perspective presents the latest progress of the synthesis of supported atomic clusters, highlights how the structure affects catalytic properties, and discusses the limitations as well as prospects., Supported atomic clusters with precise nuclearity are intermediate states between single-atom catalysts and nanoparticles in size. Here the authors summarize and discuss synthetic strategies of supported atomic clusters with unique catalytic properties for heterogeneous reactions.

Summary Surface vacancy engineering played a significant role in tailoring the structure and improving the performance of semiconductor nanocrystals (SNCs). Developing controllable vacancy engineering strategies to overcome kinetic energy barriers in multi-step reactions is anticipated to explore further synthesis mechanisms and functional nanomaterials. Herein, we exploited an effective surface-vacancy-engineering-initialized cation exchange (SVEICE) strategy to realize energy-unfavored cation exchange reactions from ternary CuInX2 (X = S, Se) to Cu, In dual-doped binary CdX, or ZnX SNCs, unprecedentedly. The sequential and selective creation of Cu and In vacancies on multi-component SNC surface is critical to break through kinetic energy barriers. The emission of dual-doped CdS:Cu/In SNCs crossed visible-NIR region due to the radiative transition from doped In level to Cu-doped e- or t-level, and the radiative recombination process could also be tailored by this strategy. Further energy analysis and experiments confirmed its versatility.

Self-assembly of colloidal nanocrystals (NCs) into large-scale superlattices with complex and controllable structures has attracted extensive attention due to their collective properties and promising device applications. Plasmonic NCs are very popular for long-range ordered superstructures by virtue of their collective nanogaps for electromagnetic field enhancement, in particular bulk-scale single-layer assembly. Large-area two-dimensional (2D) quasinanosheets (QNSs) composed of mono-component Au NCs or multi-component Au@ZnS core-shell hetero-nanocrystals (HNCs) were successfully prepared, via careful solvent evaporation-induced interfacial self-assembly. The entire self-assembly process was carried out on the liquid-air surface and mediated simply by tuning the operating temperatures and concentrations of the NCs. Specifically, monolayer and double-layer 2D QNSs in tens of micrometers scale with different stacking models were fabricated by precisely controlling the solvent evaporation rate and colloidal concentration.

The local coordination environment of catalysts has been investigated for an extended period to obtain enhanced catalytic performance. Especially with the advancement of single-atom catalysts (SACs), research on the coordination environment has been advanced to the atomic level. The surrounding coordination atoms of central metal atoms play important roles in their catalytic activity, selectivity and stability. In recent years, remarkable improvements of the catalytic performance of SACs have been achieved by the tailoring of coordination atoms, coordination numbers and second- or higher-coordination shells, which provided new opportunities for the further development of SACs. In this review, the characterization of coordination environment, tailoring of the local coordination environment, and their related adjustable catalytic performance will be discussed. We hope this review will provide new insights on further research of SACs.

Summary The last 5 years have witnessed rapid progress in the field of hybrid nanostructures toward enhanced optical and electronic properties. On this topic, we focus on the relevant progress that has been achieved on the basis of cation/anion exchange reactions (CERs/AERs). Different from those direct synthesis strategies, CERs/AERs can offer more freedom in tuning the chemical composition, crystal phases, doping, interfaces, and morphologies, which are key parameters to determine the optical and electronic properties of the target products. We present several examples, e.g., doped quantum dots (QDs), engineered core-shell QDs, metal-semiconductor hybrid nanostructures, hollow structures, and inorganic perovskite nanocrystals. These upgraded structures afforded by CERs/AERs generally exhibit improved properties, such as increased quantum yields, prolonged lifetimes, and well-engineered band gaps for charge transportation and recombination, thus providing more opportunities for further advanced applications.

Dilute alloy nanostructures have been demonstrated to possess distinct catalytic properties. Noble-metal-induced reduction is one effective synthesis strategy to construct dilute alloys and modify the catalytic performance of the host metal. Herein, we report the synthesis of ultrafine PtRu dilute alloy nanodendrites (PtRu NDs, molar ratio Ru/Pt is 1:199) by the reduction of RuIII ions induced by Pt metal. For the methanol oxidation reaction, PtRu NDs showed the highest forward peak current density (2.66 mA cm-2 , 1.14 A/mgPt ) and the best stability compared to those of pure-Pt nanodendrites (pure-Pt NDs), commercial PtRu/C and commercial Pt/C catalysts.

The electrocatalytic reduction reaction of CO2 (CO2RR) is a promising strategy to promote the global carbon balance and combat global climate change. Herein, exclusive Bi-N4 sites on porous carbon ...

Utilizing vacuum-tuned-atmosphere induced dip coating method, we achieve the cross-dimensional macroscopic diverse self-assemblies by using one building block with one chemical functionality. Coordinated modulating the vacuum degree, colloid concentration and evaporation atmosphere, Au@Ag core/shell NCs can controllably assemble into diverse multi-dimensional superstructures. Under 0.08 MPa, we obtained the two-dimensional (2D) stepped superstructures with continuously tunable step width. In addition, we generated a series of tailorable nanoscale-roughened 2D Au@Ag NCs superstructures at 0.04 MPa, which exhibited the label-free ultrasensitive SERS detection for the different mutants of IAPP8-37 proteins. Under 0.01 MPa, we obtained the cross-dimensional tailorable Au@Ag NCs assemblies from random to macroscale 2D and three-dimensional (3D) densest superstructures by adjusting the capping ligand-environmental molecule interactions. This is a flexible method to generate as-prepared Au@Ag core/shell NCs into well-defined macroscopic diverse superstructures and to promote the exploitation into biological applications.

Control of surface structure at the atomic level can effectively tune catalytic properties of nanomaterials. Tuning surface strain is an effective strategy for enhancing catalytic activity; however, the correlation studies between the surface strain with catalytic performance are scant because such mechanistic studies require the precise control of surface strain on catalysts. In this work, a simple strategy of precisely tuning compressive surface strain of atomic-layer Cu2O on Cu@Ag (AL-Cu2O/Cu@Ag) nanoparticles (NPs) is demonstrated. The AL-Cu2O is synthesized by structure evolution of Cu@Ag core-shell nanoparticles, and the precise thickness-control of AL-Cu2O is achieved by tuning the molar ratio of Cu/Ag of the starting material. Aberration-corrected high-resolution transmission electron microscopy (AC-HRTEM) and EELS elemental mapping characterization showed that the compressive surface strain of AL-Cu2O along the [111] and [200] directions can be precisely tuned from 6.5% to 1.6% and 6.6% to 4.7%, respectively, by changing the number of AL-Cu2O layer from 3 to 6. The as-prepared AL-Cu2O/Cu@Ag NPs exhibited excellent catalytic property in the synthesis of azobenzene from aniline, in which the strained 4-layers Cu2O (4.5% along the [111] direction, 6.1% along the [200] direction) exhibits the best catalytic performance. This work may be beneficial for the design and surface engineering of catalysts toward specific applications.

Thiol- and solvent-coordinated cation exchange kinetics have been applied to engineer the composition and crystallinity of novel nanocrystals. The detailed thermodynamics and kinetics of the reactions were explored by NMR spectroscopy, time-dependent photoluminescence (PL) characterizations and theoretical simulations. The fine structure of the colloidal semiconductor nanocrystals (CSNCs) was investigated by X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). In this way, high-quality p-type Ag-doped ZnS quantum dots (QDs) and Au@ZnS hetero-nanocrystals with a cubic phase ZnS shell were synthesized successfully.The unprecedented dominant Ag+ -dopant-induced fluorescence and p-type conductivity in the zinc-blende ZnS are reported.

Doping-related point defect engineering in low-dimensional semiconductor nanostructures is important to regulate their optical and electronic properties. The substitutional or interstitial location of heterovalent dopants is critical and has not been controlled effectively yet. Herein, we carefully control the kinetics of reverse cation exchange between CuxS 2D nanosheets and ligand-coordinated Cd2+ cations to control the Cu doping sites in CdS nanosheets (NSs). The substitutional and interstitial Cu dopants were directly confirmed by spherical aberration-corrected TEM (SACTEM) and their X-ray absorption spectroscopy (XAS) coordination investigation. Density functional theory (DFT) calculations and their experimental conductivities and dopant luminescence performance demonstrated the dramatic differences that are due to the location of different Cu dopants. These findings provide deeper insights on dopants' location regulation in a nanostructured host semiconductor.

We successfully fabricate a novel concave nanostructure that is composed of atomically dispersed Ru atoms in Pt

Construction of hollow anisotropic semiconductor nanostructures that possess excellent crystallinity, a flexibly tunable structure/morphology and aqueous dispersity is of special interest for many promising applications such as photoelectrochemical (PEC) water splitting, but has long been hindered by great synthetic challenges. Here we report a powerful and widely applicable approach to fulfill this vision based on cation exchange-induced oxidative etching. Aqueous cation exchange is utilized to chemically convert the shells growing around the shape-controlled Ag templates (such as 2D Ag triangle nanoprisms) into desired semiconductor components (MS, M = Cd and Zn). Remarkably, we found that the soft base ligand used to initiate the cation exchange process can simultaneously induce oxidative etching of the Ag domain forming anisotropic Ag@MS core–shell hybrid nanocrystals, Ag@MS partially hollow hybrid nanocrystals with a controlled degree of hollowness, and hollow MS nanocrystals, depending on the strength of oxidative etching. The resulting core–shell or hollow nanoprisms all exhibit well-defined geometry and crystallinity/interface properties, and this is presumed to be the major reason for their highly efficient performance as the photoanode materials for PEC hydrogen generation.

Two-dimensional (2D) CdX (X = Se, Te) nanosheets are potential candidates for novel optoelectronic applications. Herein, oleic acid (OA), stearic acid (SA) and typical Cd precursors were chosen to synthesize high-quality 2D CdX nanosheets. Their unique absorption (or excitation) and photoluminescence (PL) properties were studied. The PL profiles are differentiated as band-edge and trap-state PL. These trap-states emanated from the intrinsic surface defect sites (Cd2+ or Se2−). The intrinsic defect sites were generated because of the bonding termination at the surface of the nanosheets. A complex formed by the Cd-interstitial (Cdi–VCd) acts as a donor–acceptor pair according to the Prener–Williams model and is accountable for the large Stokes-shifted trap-state PL peak. Our experimental findings imply that these surface trap-states follow the configurational coordinates model. Inevitably, the PL dynamics of CdSe nanosheets depend strongly on the surface trap-states in addition to their size and shape.

The facet effect has been well demonstrated for nanocrystal catalysis, however it is rarely revealed in metal organic frameworks (MOFs). Herein, we present a facile way to construct 2D zeolitic imidazolate framework-67 (ZIF-67) with dominant exposure of the (002) facets. We discovered that the ZIF-67 (002) facet exhibited the highest catalytic activity for oxygen evolution reaction (OER) among the (002), (011), and (111) facets. Moreover, this facet engineering is also available for ZIF-8 nanocrystals.

Differently from the normal three single precursor method to produce colloidal ternary quantum dots (QDs), herein ternary Ag3 SbS3 quantum dots (QDs) with efficient near-infrared (NIR) luminescence have been prepared by a new facile in situ conversion of Ag nanocrystals (NCs) with a binary Sb/S organic precursor Sb(C9 H19 COOS)3 under low temperature. The unprecedented construction evolution from Ag NCs to Ag3 SbS3 /Ag hetero-structure and final monodisperse Ag3 SbS3 QDs has been demonstrated. These novel Ag3 SbS3 QDs exhibit efficient NIR emission at ≈1263 nm and possess high colloidal stability.

Focusing on ternary I-III-VI2 colloidal nanocrystals (NCs) synthesized with precise control of the composition (from doping to ternary composition) and NIR fluorescence performance, monodisperse binary In3+ -doped Ag2 S NCs and ternary AgInS2 NCs have been achieved successfully by facile low-temperature in situ conversion of colloidal Ag2 S nanoparticles. In3+ ions were inserted into the crystal lattice of Ag2 S NCs at a relatively low temperature as dopant and ternary AgInS2 NCs were obtained at a higher temperature following a phase transition. These doped Ag2 S and AgInS2 NCs based on different indium precursor concentrations were explored with respect to the position and intensity of the near-infrared photoluminescent emission at different doping levels and crystal phase evolution.

The active species in supported metal catalysts are elusive to identify, and large quantities of inert species can cause significant waste. Herein, using a stoichiometrically precise synthetic method, we prepare atomically dispersed palladium-cerium oxide (Pd1 /CeO2 ) and hexapalladium cluster-cerium oxide (Pd6 /CeO2 ), as confirmed by spherical-aberration-corrected transmission electron microscopy and X-ray absorption fine structure spectroscopy. For aerobic alcohol oxidation, Pd1 /CeO2 shows extremely high catalytic activity with a TOF of 6739 h-1 and satisfactory selectivity (almost 100 % for benzaldehyde), while Pd6 /CeO2 is inactive, indicating that the true active species are single Pd atoms. Theoretical simulations reveal that the bulkier Pd6 clusters hinder the interactions between hydroxy groups and the CeO2 surface, thus suppressing synergy of Pd-Ce perimeter.

Au@Sn2S3 and Au@SnS2 core–shell hybrid nanocrystals (HNCs) were respectively accessed via an aqueous cation exchange-mediated growth strategy by using different phosphine ligands. The choice of proper ligands during synthesis is imperative to optimize the photoelectrochemical performance of these previously hardly accessible HNCs that manifest compelling plasmon–exciton interactions.

Interactions between light and metal nanostructures are mediated by collective excitations of free electrons called surface plasmons, which depend primarily on geometry and dielectric environment. Excitation with ultrafast pulses can excite optomechanical modes that modulate the volume and shape of nanostructures at gigahertz frequencies. Plasmons serve as an optical handle to study the ultrafast electronic dynamics of nanoscale systems. We describe a method to synthesize core-shell Ag@TiO2 nanocubes-while successfully maintaining the size and shape of the nanocube. Transient absorbance spectroscopy (TAS) is used to track photophysical processes on multiple time scales: from the ultrafast creation of hot carriers to their decay into phonons and the formation of optomechanical modes. Surprisingly, the TiO2 shell surrounding the Ag nanocubes caused no appreciable change in the frequency of the optomechanical mode, indicating that mechanical coupling between the core and shell is weak. However, the optomechanical mode was strongly attenuated by the TiO2 shell and TAS decay at ultrafast time scales (0-5 ps) was much faster. This observation suggests that up to-36% of the energy coupled into the plasmon resonance is being lost to the TiO2 as hot carriers instead of coupling to the optomechanical mode. Analysis of both ultrafast decay and characterization of optomechanical modes provides a dual accounting method to track energy dissipation in hybrid metal-semiconductor nanosystems for plasmon-enhanced solar energy conversion and chemical fuel generation.

Here, the photocatalytic CO

The electrocatalytic reduction reaction of CO

We experimentally determined the dispersion of the complex third-order nonlinear optical susceptibility χ(3) of Au nanorods over a wide bandwidth (370 – 800 nm). Compared to bulk Au, these nanorods exhibit greatly enhanced nonlinearities that can be manipulated by geometrical parameters. Accurately measuring the χ(3) values of nanostructured metals is challenging because χ(3) is strongly influenced by the local field effects. Hence the current published χ(3) values for Au nanorods have huge variations in both magnitude and sign because Z-scan measurements are used almost exclusively. This work combines pump-probe methods with spectroscopic ellipsometry to show that Au nanorods exhibit strong wavelength dependence and enhanced χ(3) in the vicinity of the longitudinal plasmon mode and explains where the regions of SA and RSA exist and how focusing and defocusing affects χ(3). In this context, the results highlight the importance of the dispersion of the quantity χ(3) to design plasmonic platforms for nanophotonics applications.

Hollow-structured semiconductor nanocrystals (NCs) have aroused tremendous research interest because of their compelling structure-related properties that can facilitate the development of many important applications including solar water splitting. However, the creation of multicomponent semiconductor NCs (such as I-III-VI

The insertion of cation impurities into quantum dots (QDs) as a dopant has been proved to be an efficient way to tailor their optical, electronic, and magnetic properties; however, the low quantum yield (QY) and poor photostability strongly limit their further applications. We report a strategy to coat a thin oxide shell around the heterovalent doped QDs to enhance their QYs and photostabilities simultaneously. In the case of Ag+-doped CdS QDs, the controlled cation exchange reaction between Cd2+ and ternary Ag3SbS3 nanoparticles not only realizes the Ag+ doping in CdS QDs but also generates a thin Sb2O3 shell around the surface of the QDs. Enabled by such, as-prepared CdS:Ag@Sb2O3 QDs exhibited enhanced photostability and high QY of 66.5%. We envision that the findings presented here will inspire more novel protocols for advancing the practical applications of doped QDs.

We have explored the synthesis of Au@HgxCd1-xTe core@shell nanorods by sequential aqueous cation exchange (ACE) for near-infrared photodetector application. A number of related Au@telluride core/shell nanorod structures were put forwarded, taking advantage of multi-step transformations through a binary and then a ternary phase for the telluride shells. The latter have a high degree of crystallinity thanks to the step-wise ACE method. The use of only trace amounts of Cd2+ coordinated with tri-n-butylphosphine, assisted the phase transformation from an amorphous Ag2Te shell to a highly crystalline Ag3AuTe2 shell in the first stage; this was followed by a further cation exchange (CE) step with far higher Cd2+ levels to fabricate a highly crystalline CdTe shell, and with an additional CE with Hg2+ to convert it to a HgxCd1-xTe shell. The composition of the shell components and the well-controlled thickness of the shells enabled tunable surface plasmon resonance properties of the Au@telluride nanorods in the NIR region. Utilizing the enhanced NIR absorption, a hybrid photodetector structure of Au@HgxCd1-xTe nanorods on graphene was fabricated, showing visible to NIR (vis-NIR) broadband detection with high photoresponsivity (~106 A/W).

Differently from the normal three single precursor method to produce colloidal ternary quantum dots (QDs), herein ternary Ag

Au@Sn

Focusing on ternary I-III-VI

We successfully obtained truncated octahedron PtAl alloy nanocrystals (∼10 nm) via a facile one-pot strategy. The PtAl nanocrystals exhibited enhanced activity in formic acid electrooxidation compared to commercial Pt/C, which could be ascribed to the large density of defects on the surface as well as the synergy between Pt and Al.

Perovskite nanocrystals (NCs), which are a good fluorescence candidate with excellent photoelectric properties, have opened new avenues in the fabrication of highly efficient solar cells, light-emitting diodes (LEDs), and other optoelectronic devices. Further advances will rely on the multitude of compositional, structural variants that enable the formation of lower-dimensionality layered and three-dimensional (3D) perovskites with architectural innovations. In this work, the perovskite film was fabricated on a flexible substrate using simple dip-coating technology and 3D assemblies of perovskite NCs were obtained through an attachment process. Original perovskite NCs had a rectangular or square morphology with high particle uniformity and the narrow and symmetric fluorescence emission peak was adjustable at 515-527 nm. The controllable self-assembly of the micron size cuboid-like 3D assembly had an apparent enhancement on peak (111) in the x-ray diffraction (XRD) pattern. Surface ligands not only play a role in the attachment process but also keep the independence of each NC in 3D assemblies. Such assembly of the perovskite film maintained the original perovskite NCs fluorescence emission peak and narrow full width at the half-maximum (FWHM), which is of great importance for the investigation of future devices.

Liquid phase one-pot synthesis of semiconductor nanocrystals, by direct nucleation-growth crystallization, is unsuccessful for synthesis of some kinds of semiconductors. Using ZnTe as an example here, highly disperse ZnTe nanoclusters with diameters of 2-3 nm were first synthesized by a facile solvothermal method. Then the ZnTe nanoclusters were chosen as starting crystallization seeds to mediate the synthesis of flexible semiconductor nanostructures. Three-dimensional (3D) oriented assembly of ZnTe nanoclusters to monodisperse dendrimer-like nanocrystals (DLNCs), and one-dimensional (1D) ZnTe nanobelts with cubic phase, have been achieved successfully. Supported by TEM characterization of time-dependent morphology evolution, the oriented attachment assisted seed growth, based on ZnTe nanoclusters, enabled the 1D flexible ZnTe nanobelts formation, which could reach to ≈10 micrometers length.

Ag nanoparticle-catalyzed aerobic oxidation of benzyl alcohols in basic DMSO gave efficient formation of styryl ethers, featuring single carbon transfer and C═C and C–O bond formation. A deuterium labeling experiment established that DMSO was the carbon source. Further experiments showed the reaction proceeded through a styryl sulfoxide intermediate originating from basic DMSO and transient benzaldehyde. Control reactions in the absence of the Ag NPs or air indicated that oxidation of the styryl sulfoxide was required for the final C–O bond formation. This work demonstrated that metal nanoparticles could be applied to tandem heterogeneous catalysis in organic chemistry.

Ag–Pd bimetallic nanocrystals (NCs) with tunable compositions and narrow size distributions were produced by a one-pot synthesis. The NC growth process was investigated by time-dependent TEM, XRD, and UV–vis studies. In the hydrodechlorination of 4-chlorophenol, the AgPdx (x = 2, 4, 6, 9, 19) showed pronounced composition-dependent catalytic activities, leading to the AgPd9 catalyst with excellent activity.

Because of the requirements of sustainable development as well as the desirability of using molecular hydrogen as a chemical reagent, it is of paramount importance and great challenge to develop highly active and selective catalysts for the hydrogenation of organic molecules, including substituted nitroarenes. We approach this question by probing unsupported bimetallic nanoparticles. A series of novel bimetallic RhxNiy (x, y = 1, 2, 3) nanoparticles were successfully prepared using our “noble metal-induced reduction” strategy. Unsupported Rh3Ni1 nanoparticles were subsequently identified to be a highly active and exceedingly selective catalyst for the hydrogenation of nitroarenes under ambient conditions, underscoring a remarkable synergistic effect of the two metals. Further experiments showed that the Rh3Ni1 catalyst could be a highly efficient, selective, and recyclable catalyst for a range of nitroarene substrates. This work showcased the value of bimetallic nanoparticles in catalysts development for ...

It is highly challenging but desirable to develop efficient catalysts for the activation of oxygen under mild conditions. Here, we report that various monodispersed metal nanoparticles (Ag, Pt, Co, Cu, Ni, Pd, and Au) efficiently activated molecular oxygen under mild conditions, illustrated by the aerobic oxidation of anilines to form either symmetric or asymmetric aromatic azo compounds. This discovery indicates that exploiting the catalytic power of nanoparticles could enable sustainable chemistry suitable for important oxidation reactions.