Facile one-step synthesis and transformation of Cu(I)-doped zinc sulfide nanocrystals to Cu(1.94)S-ZnS heterostructured nanocrystals

Influence of zinc doping on the molecular biocompatibility of cadmium-based quantum dots: Insights from the interaction with trypsin

Doping quantum dots (QDs) with extra element presents a promising future for their applications in the fields of environmental monitoring, commercial products and biomedical sciences. However, it remains unknown for the influence of doping on the molecular biocompatibility of QDs and the underlying mechanisms of the interaction between doped-QDs and protein molecules. Using the "one-pot" method, we synthesized N-acetyl-l-cysteine capped CdTe: Zn²⁺ QDs with higher fluorescence quantum yield, improved stability and better molecular biocompatibility compared with undoped CdTe QDs. Using digestive enzyme trypsin (TRY) as the protein model, the interactions of undoped QDs and Zn-doped QDs with TRY as well as the underlying mechanisms were investigated using multi-spectroscopy, isothermal titration calorimetry and dialysis techniques. Van der Waals forces and hydrogen bonds are the major driving forces in the interaction of both QDs with TRY, which leading to the loosening of protein skeleton and tertiary structural changes. Compared with undoped QDs, Zn-doped QDs bind less amount of TRY with a higher affinity and then release higher amount of Cd. Zn-doped QDs have a less stimulating impact on TRY activity by decreasing TRY binding and reducing Cd binding to TRY. Taken all together, Zn-doped QDs offer a safer alternative for the applications of QDs by reducing unwanted interactions with proteins and improving biocompatibility at the molecular level.

Efficient electrochemical reduction of CO2 promoted by the electrospun Cu1.96S/Cu tandem catalyst

Coupled with renewable electricity, electrochemical reduction of CO₂ (CO₂RR) is one of the sustainable strategies for the production of value-added carbon-containing chemicals. Cu-based catalysts are by far the most widely studied electrocatalytic materials for CO₂RR, although they exhibit poor performance in CO selectivity. In this work, we have designed a Cu_1.96S/Cu tandem structure via a combined electrospinning and calcination method. The catalyst enables CO₂ reduction to CO with high selectivity >80% with a production rate of 34.6 μmol h^-1 cm^-2 at -0.68 V vs. RHE, which is superior to most of the Cu-based catalysts under the same operation conditions. Theoretical simulations show that the improved CO₂RR performance stems from the Cu_1.96S/Cu tandem structure in which Cu acts as a *CO-producing site and the neighboring Cu_1.96S facilitates the following *CO desorption step. This work opens new possibilities for exploiting tandem catalysis mechanisms.

Synthesis and Formation Mechanism of Colloidal Janus-Type Cu2-xS/CuInS2 Heteronanorods via Seeded Injection

Colloidal heteronanocrystals allow for the synergistic combination of properties of different materials. For example, spatial separation of the photogenerated electron and hole can be achieved by coupling different semiconductors with suitable band offsets in one single nanocrystal, which is beneficial for improving the efficiency of photocatalysts and photovoltaic devices. From this perspective, axially segmented semiconductor heteronanorods with a type-II band alignment are particularly attractive since they ensure the accessibility of both photogenerated charge carriers. Here, a two-step synthesis route to Cu_2-xS/CuInS₂ Janus-type heteronanorods is presented. The heteronanorods are formed by injection of a solution of preformed Cu_2-xS seed nanocrystals in 1-dodecanethiol into a solution of indium oleate in oleic acid at 240 °C. By varying the reaction time, Janus-type heteronanocrystals with different sizes, shapes, and compositions are obtained. A mechanism for the formation of the heteronanocrystals is proposed. The first step of this mechanism consists of a thiolate-mediated topotactic, partial Cu⁺ for In³⁺ cation exchange that converts one of the facets of the seed nanocrystals into CuInS₂. This is followed by homoepitaxial anisotropic growth of wurtzite CuInS₂. The Cu_2-xS seed nanocrystals also act as sacrificial Cu⁺ sources, and therefore, single composition CuInS₂ nanorods are eventually obtained if the reaction is allowed to proceed to completion. The two-stage seeded growth method developed in this work contributes to the rational synthesis of Cu_2-xS/CuInS₂ heteronanocrystals with targeted architectures by allowing one to exploit the size and faceting of premade Cu_2-xS seed nanocrystals to direct the growth of the CuInS₂ segment.

Seeded Growth Combined with Cation Exchange for the Synthesis of Anisotropic Cu2-x S/ZnS, Cu2-x S, and CuInS2 Nanorods

Colloidal copper(I) sulfide (Cu_2-x S) nanocrystals (NCs) have attracted much attention for a wide range of applications because of their unique optoelectronic properties, driving scientists to explore the potential of using Cu_2-x S NCs as seeds in the synthesis of heteronanocrystals to achieve new multifunctional materials. Herein, we developed a multistep synthesis strategy toward Cu_2-x S/ZnS heteronanorods. The Janus-type Cu_2-x S/ZnS heteronanorods are obtained by the injection of hexagonal high-chalcocite Cu_2-x S seed NCs in a hot zinc oleate solution in the presence of suitable surfactants, 20 s after the injection of sulfur precursors. The Cu_2-x S seed NCs undergo rapid aggregation and coalescence in the first few seconds after the injection, forming larger NCs that act as the effective seeds for heteronucleation and growth of ZnS. The ZnS heteronucleation occurs on a single (100) facet of the Cu_2-x S seed NCs and is followed by fast anisotropic growth along a direction that is perpendicular to the c-axis, thus leading to Cu_2-x S/ZnS Janus-type heteronanorods with a sharp heterointerface. Interestingly, the high-chalcocite crystal structure of the injected Cu_2-x S seed NCs is preserved in the Cu_2-x S segments of the heteronanorods because of the high-thermodynamic stability of this Cu_2-x S phase. The Cu_2-x S/ZnS heteronanorods are subsequently converted into single-component Cu_2-x S and CuInS₂ nanorods by postsynthetic topotactic cation exchange. This work expands the possibilities for the rational synthesis of colloidal multicomponent heteronanorods by allowing the design principles of postsynthetic heteroepitaxial seeded growth and nanoscale cation exchange to be combined, yielding access to a plethora of multicomponent heteronanorods with diameters in the quantum confinement regime.

A General One-Pot Approach to Synthesize Binary and Ternary Metal Sulfide Nanocrystals

A general one-pot approach is developed to synthesize a series of binary metal sulfide nanocrystals (NCs) including PbS, Cu₂S, ZnS, CdS, Ag₂S, and ternary CuInS₂ and CdS:Cu(I) NCs. This synthetic approach involves thermal decomposition of the mixture of inorganic metal salts and n-dodecanethiol (DDT) without pre-synthesis of any organometallic precursors. In this method, layered metal-thiolate compound is formed at the beginning of the reaction and then this intermediate compound is decomposed into small particles, leading to further growth as the reaction time increases. The as-obtained CdS NCs exhibits a broad but weak surface-state emission, and the Cu(I) doping leads to a red-shift of the emission band due to the Cu(I)-related emission. It is expected that this one-pot approach can be extended to prepare multinary metal sulfide NCs.

Insight into the crystal phase and shape evolution from monoclinic Cu1.94S to wurtzite Cu2ZnSnS4 nanocrystals

The Sn content greatly influences the morphology of CZTS NCs when using Cu_1.94S nanoplates as starting materials.

Formation of uniform carrot-like Cu31S16-CuInS2 heteronanostructures assisted by citric acid at the oil/aqueous interface

A simple two-phase strategy was developed to prepare Cu₃₁S₁₆-CuInS₂ heterostructures (HNS) at the oil/aqueous interface, in which the In(OH)₃ phase was often obtained in the products due to the reaction between indium ions and hydroxyl ions in the aqueous phase. To prevent the formation of the In(OH)₃ phase, citric acid was incorporated into the aqueous phase to assist in the synthesis of uniform carrot-like Cu₃₁S₁₆-CuInS₂ semiconductor HNS at the oil/aqueous interface for the first time. By manipulating the dosage of citric acid and Cu/In precursor ratios, the morphology of the Cu₃₁S₁₆-CuInS₂ HNS could be tailored from mushroom to carrot-like, and the presence of citric acid played a critical role in the synthesis of high-quality Cu₃₁S₁₆-CuInS₂ HNS, which inhibited the formation of the In(OH)₃ phase due to the formation of the indium(iii)-citric acid complex. The formation mechanism was studied by monitoring the morphology and phase evolution of the Cu₃₁S₁₆-CuInS₂ HNS with reaction time, which revealed that the Cu₃₁S₁₆ seeds were first formed and then the cation-exchange reaction directed the subsequent anisotropic growth of the Cu₃₁S₁₆-CuInS₂ HNS.

Diversified copper sulfide (Cu2-xS) micro-/nanostructures: a comprehensive review on synthesis, modifications and applications

As a significant metal chalcogenide, copper sulfide (Cu_2-xS, 0 < x < 1), with a unique semiconducting and nontoxic nature, has received significant attention over the past few decades. Extensive investigations have been employed to the various Cu_2-xS micro-/nanostructures owing to their excellent optoelectronic behavior, potential thermoelectric properties, and promising biomedical applications. As a result, micro-/nanostructured Cu_2-xS with well-controlled morphologies, sizes, crystalline phases, and compositions have been rationally synthesized and applied in the fields of photocatalysis, energy conversion, in vitro biosensing, and in vivo imaging and therapy. However, a comprehensive review on diversified Cu_2-xS micro-/nanostructures is still lacking; therefore, there is an imperative need to thoroughly highlight the new advances made in function-directed Cu_2-xS-based nanocomposites. In this review, we have summarized the important progress made in the diversified Cu_2-xS micro-/nanostructures, including that in the synthetic strategies for the preparation of 0D, 1D, 2D, and 3D micro-/nanostructures (including polyhedral, hierarchical, hollow architectures, and superlattices) and in the development of modified Cu_2-xS-based composites for enhanced performance, as well as their various applications. Furthermore, the present issues and promising research directions are briefly discussed.

Shape-controlled synthesis of Cu31S16-metal sulfide heteronanostructures via a two-phase approach

A series of different-shaped Cu31S16-metal sulfide (ZnS, CdS and CuInS2) heteronanostructures have been synthesized using a simple two-phase approach for the first time. This two-phase approach may shed light on the synthesis of Cu31S16-based heteronanostructures.

Tuning emission and Stokes shift of CdS quantum dots via copper and indium co-doping

Cu and In co-doped CdS QDs are synthesized and exhibit large Stokes shifts and tunable emission from green to near-infrared.

One-pot synthesis of CuInS2 nanocrystals using different anions to engineer their morphology and crystal phase

The effects of anions on the phases and morphologies of ternary CuInS₂ nanocrystals have been described.

Understanding the roles of metal sources and dodecanethiols in the formation of metal sulfide nanocrystals via a two-phase approach

We present a two-phase approach for controllable synthesis of metal sulfide nanocrystals, such as Cu_2−xS, Ag₂S and Ni₉S₈, in which the reaction takes place at the water/oil interface.

Synthesis and characterization of bis (acetylacetonato κ-O, O′) [zinc(ii)/copper(ii)] hybrid organic–inorganic complexes as solid metal organic precursors

We have synthesized novel metal organic hybrid mixed compounds of bis (acetylacetonato κ-O, O′) [zinc(ii)/copper(ii)].

Phase-selective synthesis and formation mechanism of CZTS nanocrystals

In this paper, we present a simple and feasible phase-selective synthetic approach to kesterite-phase and wurtzite-phase CZTS nanocrystals by controlling the concentration of sulfur and DDT.

Synthesis and photo-darkening/photo-brightening of blue emitting doped semiconductor nanocrystals

By programming the synthetic reaction chemistry, stable blue emitting Cu(i) or Ag(i) doped Al(iii) co-doped ZnS (Al,Cu:ZnS or Al,Ag:ZnS) semiconductor nanocrystals are designed. Further, the photostability of the obtained intense blue-violet emission is studied, and the effects of doping/co-doping are correlated. Finally, it is revealed that the strong binding surface ligand 1-dodecanethiol and Al(iii) co-doping play pivotal roles in achieving such stable blue emitting doped nanocrystals.

Solution-phase catalytic synthesis, characterization and growth kinetics of Ag2S–CdS matchstick-like heteronanostructures

Ag₂S nanocrystals are catalytically active in the growth of CdS nanorods in oleylamine, and the reaction yields Ag₂S–CdS matchstick-like heteronanostructures.

Effects of alkanethiols chain length on the synthesis of Cu2−xS nanocrystals: phase, morphology, plasmonic properties and electrical conductivity

We synthesized Cu_2−xS nanocrystals with different shapes and phases by using alkanethiols with varying chain length as sulfur sources.

Synthesis of Cu2−xS nanocrystals induced by foreign metal ions: phase and morphology transformation and localized surface plasmon resonance

Phase and morphology transformation of Cu_2−xS nanocrystals takes place by the addition of foreign metal ions (such as Zn²⁺ and Cd²⁺) into the precursor solution, and the LSPR behavior exhibits a strong dependence on the amount of foreign ions.