Integrating a plasmonic metal and a semiconductor at the nanoscale is of great importance for exploring their optical coupling properties. However, the synthesis and fine structural control of such nanostructures remain challenging. Herein we report the facile aqueous-phase Se-mediated overgrowth of metal selenides onto Au nanocrystals. Taking plasmonic Cu2–xSe as an example, the introduction of a Se template allows deposition of large Cu2–xSe crystalline grains onto Au nanocrystal seeds in various shapes, including spheres, rods, and plates. Moreover, the configuration of Au–Cu2–xSe hybrids can be tuned from core–shell to heterodimer structure by controlling the growth behavior of the Se template. Se overgrowth depends critically on the absorption strength of stabilizers on Au seeds: a strongly absorbing stabilizer inhibits isotropic overgrowth, which is in agreement with molecular dynamics simulations. The resultant Au–Cu2–xSe hybrid nanocrystals possess multiple surface plasmon resonance modes. Finally, our synthetic strategy can be extended to prepare other Au–metal selenide hybrids such as Au–Ag2Se and Au–CdSe with controllable morphologies.Keywords: copper chalcogenide nanocrystals; core−shell; doped semiconductor nanocrystals; geometry control; heteronanostructures; hybrid nanoparticles; metal−semiconductor; plasmon resonance;

Plasmonic Au–copper sulfides hybrid nanocrystals are of great interest for both fundamental research and application in optoelectronics, catalysis, and biomedicine, in which a precise and high-yield synthesis of the hybrid nanocrystals is required. Herein, we investigated colloidal synthesis of Au–CuS hybrid nanocrystals based on a seed-mediated method. Different from previously reported deposition of Cu-rich Cu chalcogenides, we found that decreasing the Cu–S reaction rate is critical for the deposition of relatively S-rich CuS on Au seeds in high yield, which can be achieved by using a chlorobenzene solution containing a small amount of oleylamine as the solvent. The influence of the S/Cu feed molar ratio and reaction temperature on the formation of Au–CuS hybrid nanocrystals has also been investigated. The obtained Au–CuS hybrids showed better photothermal transduction efficiency over CuS nanocrystals prepared under identical conditions. In addition, Au–CuS hybrids could be used as templates to synthesize Au–CuInS2 and Au–Cu2ZnSnS4 hybrid nanocrystals via subsequent reactions with In or Zn/Sn precursors at high temperature. These results provide insight into the critical parameters governing the growth of Au–copper sulfides hybrid nanostructures, which can be useful for the design of other noble metal–semiconductor hybrid nanostructures.

•Gd-doped CuInS2 quantum dots were synthesized through a simple heat-up reaction.•Gd-doping slowed down the growth of CuInS2 quantum dots.•Gd-doping reduced the photoluminescence intensity of quantum dots slightly.•Gd-doping endowed quantum dots with high relaxivity.Paramagnetic ions-doped quantum dots (QDs) are attractive dual-modal imaging agents for fluorescence and magnetic resonance imaging. In this work, we report the synthesis of water-soluble Gd-doped CuInS2 (CuInS2:Gd) QDs by incorporating paramagnetic Gd3+ ions into CuInS2 QDs in organic solvents and subsequent surfactant-assisted phase transfer. The Gd doping was realized through a simple heat-up reaction and the growth kinetics of Gd-doped CuInS2 QDs was discussed on the basis of the temporal evolution of the sizes and elemental compositions of the QDs. The effect of Gd doping on the photoluminescence properties of the QDs was also investigated. After encapsulation with polymer surfactants, the obtained water soluble CuInS2:Gd QDs exhibited excellent aqueous stability, ultra small size and a large longitudinal relaxivity (r1) of 12.84 mM−1 s−1, showing great promise as dual fluorescent-paramagnetic nanoprobes for bio-imaging applications.

Nanocomposites combining magnetic and plasmonic components have received widespread attention in recent years due to their potential applications in biomedical research. Herein, we describe a facile method for growing small iron oxide nanoparticles on various plasmonic core materials with different shapes and surfaces by utilizing a polypyrrole interlayer. By focusing on Au nanorod@polypyrrole@iron oxide (Au NR@PPy@FexO) nanocomposites, we show that these systems exhibit a low r2/r1 ratio of 4.8, making them efficient T1 positive contrast-enhancing agents for magnetic resonance imaging (MRI). Moreover, we show that the nanocomposites are excellent photothermal agents in the second near infrared region, with high photothermal conversion efficiency, reaching up to 46%. In addition, the Au NR@PPy@FexO nanocomposites show very low cytotoxicity. In summary, the present results highlight the great potential of the synthetic method and the nanocomposites developed in this study for T1 MRI and/or infrared thermal imaging-guided photothermal cancer therapeutic applications.

As one of the best materials for surface-enhanced Raman scattering (SERS), Ag suffers from its tendency to oxidation, posing serious limitations for its use as a reliable long-term SERS substrate. Graphene oxide (GO) is considered to be a promising SERS-active platform due to the observed chemical enhancement originating from the interaction between probe molecules and oxygen containing functional groups on its surface. Herein, we present the synthesis of core–shell GO wrapped individual Ag nanocomposites (NCs) by electrostatic assembly of GO on SiO2@Ag nanostructures. The SERS enhancement factor (EF) of probe molecules on SiO2@Ag@GO is 1.8 times that on SiO2@Ag, due to the chemical enhancement brought upon by GO. Moreover, the GO surrounding the SiO2@Ag nanoparticles (NPs) shields Ag from oxidation, making them remain stable and display highly retained SERS activities even after long-term storage, while the bare SiO2@Ag NPs would have lost ∼80% of the original activity after the same treatment. As the NCs have displayed enhanced and stable SERS activities, colloidal encapsulation by GO has been proven to be an efficient way to prepare a SERS substrate with long-term stability for practical applications.

Enhanced near-field at noble metal nanoparticle surfaces due to localized surface plasmon resonance (LSPR) has been researched in fields ranging from biomedical to photoelectrical applications. However, it is rarely explored on nonmetallic nanomaterials discovered in recent years, which can also support LSPR by doping-induced free charge carriers, let alone the investigation of an intricate system involving both. Here we construct a dual plasmonic hybrid nanosystem Au–Cu9S5 with well controlled interfaces to study the coupling effect of LSPR originating from the collective electron and hole oscillations. Cu9S5 LSPR is enhanced by 50% in the presence of Au, and the simulation results confirm the coupling effect and the enhanced local field as well as the optical power absorption on Cu9S5 surface. This enhanced optical absorption cross section, high photothermal transduction efficiency (37%), large light penetration depth at 1064 nm, excellent X-ray attenuation ability, and low cytotoxicity enable Au–Cu9S5 hybrids for robust photothermal therapy in the second near-infrared (NIR) window with low nanomaterial dose and laser flux, making them potential theranostic nanomaterials with X-ray CT imaging capability. This study will benefit future design and optimization of photoabsorbers and photothermal nanoheaters utilizing surface plasmon resonance enhancement phenomena for a broad range of applications.

•We synthesized phase pure CuSbS2 nanocrystals using dodecanethiol as ligand.•Reaction temperature and precursor molar ratio affected crystalline phase of the nanocrystals.•Growth mechanism of CuSbS2 nanocrystals was investigated, with Cu-rich nanocrystals nucleated preferentially.We report the colloidal synthesis of monodisperse phase pure chalcostibite CuSbS2 nanocrystals in high boiling point solvent. The use of dodecanethiol as ligands had an advantage over oleylamine on avoiding the hydrolysis of Sb precursor. The effect of reaction temperature and Cu/Sb feed molar ratio on the synthesis of copper antimony sulfide nanocrystals in dodecanethiol system was investigated. As a result of the reactivity difference between Cu and Sb precursors, the formation of CuSbS2 nanocrystals involves the preferential nucleation of Cu-rich nanocrystals and their subsequent reaction with remaining Sb precursors. The band gap of the resulting CuSbS2 nanocrystals was measured to be ~1.59 eV.

Cu2ZnSnS4 (CZTS) nanocrystals with different morphologies and phases have been synthesized in hot organic solvents such as dodecanethiol and oleylamine. The crystallographic phases could be controlled by the sulfur precursor and the ligand species of the metal salts used for the synthesis. When a highly reactive sulfur precursor and metal acetates were used, wurtzite CZTS nanocrystals were obtained. On the other hand, using a low-reactivity sulfur precursor or metal chlorides produced CZTS nanocrystals in a kesterite phase. The experimental results from systematic investigations indicated that the reaction rate between Zn and S precursors played a determining role for the growth of CZTS nanocrystals with different crystalline phases. A relatively faster reaction between Zn and S precursors in comparison to the Sn–S reaction favored the formation of a metastable wurtzite phase, which could be accelerated by increasing the reactivity of the S precursor. This work provided a safe and economical way to synthesize high-quality phase-controlled Cu2ZnSnS4 nanocrystals, especially wurtzite nanorods, for potential photovoltaic applications. Moreover, preliminary results show that the proposed mechanism also applies to the phase-controlled synthesis of other quaternary Cu2MSnS4 (M = Cd2+, Mn2+) nanocrystals.

Hybrid nanostructures can combine two or more functionalities in one unit and oftentimes exhibit synergistically enhanced properties compared to the simple sum of the constituents. Herein, we demonstrate the facile synthesis of Pt–CuS heterogeneous nanoparticle dimers based on the sulfidation of the corresponding bimetallic alloy templates. It begins with the preparation of CuPt alloy nanoparticles in an organic solvent, which are then converted into Pt–CuS heterodimers by reacting with elemental sulfur in octadecene at elevated temperatures. The Pt–CuS heterodimers display highly selective activity for catalyzing the methanol oxidation reaction at room temperature due to the strong electronic coupling effect between the different domains in the heterodimers. The structural transformation from alloy to heterogeneous nanomaterials may provide new opportunities to design and fabricate hybrid nanostructures with interesting physicochemical properties.

Silver has been utilized as a highly effective and broad-spectrum antibacterial agent in our daily life. However, low stability, poor long-term antibacterial efficiency, and potential environmental hazard of released Ag+ ions may limit its practical applications. Ag-graphene oxide (GO) nanocomposites have been reported to display highly enhanced antibacterial property, yet their stability and long-term antibacterial properties have not been carefully investigated. Herein, we report the synthesis of Ag@Fe2O3-GO nanocomposites with tunable loading density up to full monolayer coverage by adopting a simple phase transfer method. Compared to Ag@Fe2O3, its GO composite shows enhanced stability with Ag+ releasing rate decreased by more than two times under dialysis condition. We discover that the presence of GO not only slows down Ag nanoparticle oxidation process but also enables Ag+ ions recrystallization on GO surface. The Ag@Fe2O3-GO nanocomposites have shown better and long-term antibacterial property against both Gram-negative and Gram-positive bacteria than those of plain Ag and Ag@Fe2O3, displaying great potential as a promising long-term bactericide with suppressed environmental hazard.Keywords: antibacterial; core−shell nanoparticle; hybrid; nanocomposite; silver-graphene oxide; suppressed Ag release;

The synthesis of hybrid nanostructures has been of great interest to many material scientists, yet simple and facile routes to prepare these structures remain a difficult task with many reaction variables to tune. Herein, we report the synthesis of Au–Cu2S heterodimers from AuCu alloy nanoparticles by simply adding 1-dodecanethiol. Detailed characterization of this structural transformation process revealed that the crucial step of this synthetic approach was the alloy oxidization and subsequent formation of intermediate copper thiolate. Roles of surfactants and sulfur source have also been investigated. These observations provide critical insight into the understanding of the pathways of structure transitions from AuCu alloy to Au–Cu2S heterodimer nanoparticles, and will open up new ways of synthesizing heterodimer nanoparticles from metallic alloys.

The synthesis of hybrid nanostructures has been of great interest to many material scientists, yet simple and facile routes to prepare these structures remain a difficult task with many reaction variables to tune. Herein, we report the synthesis of Au–Cu2S heterodimers from AuCu alloy nanoparticles by simply adding 1-dodecanethiol. Detailed characterization of this structural transformation process revealed that the crucial step of this synthetic approach was the alloy oxidization and subsequent formation of intermediate copper thiolate. Roles of surfactants and sulfur source have also been investigated. These observations provide critical insight into the understanding of the pathways of structure transitions from AuCu alloy to Au–Cu2S heterodimer nanoparticles, and will open up new ways of synthesizing heterodimer nanoparticles from metallic alloys.

Hybrid nanostructures can combine two or more functionalities in one unit and oftentimes exhibit synergistically enhanced properties compared to the simple sum of the constituents. Herein, we demonstrate the facile synthesis of Pt–CuS heterogeneous nanoparticle dimers based on the sulfidation of the corresponding bimetallic alloy templates. It begins with the preparation of CuPt alloy nanoparticles in an organic solvent, which are then converted into Pt–CuS heterodimers by reacting with elemental sulfur in octadecene at elevated temperatures. The Pt–CuS heterodimers display highly selective activity for catalyzing the methanol oxidation reaction at room temperature due to the strong electronic coupling effect between the different domains in the heterodimers. The structural transformation from alloy to heterogeneous nanomaterials may provide new opportunities to design and fabricate hybrid nanostructures with interesting physicochemical properties.