Suo Hon Lim

One-Pot Synthesis of Cu1.94S−CdS and Cu1.94S−ZnxCd1−xS Nanodisk Heterostructures

Nanodisk heterostructures consisting of monoclinic Cu(1.94)S and wurtzite CdS have been colloidally synthesized for the first time. Initially, hexagonal-shaped nanodisks of Cu(1.94)S were produced upon thermolysis of a copper complex in a solvent mixture of HDA and TOA at 250 °C. Rapid addition of Cd precursor to the reaction mixture resulted in the partial conversion of Cu(1.94)S into CdS, yielding Cu(1.94)S-CdS nanoheterostructures. The original morphology of the Cu(1.94)S nanodisks was conserved during the transformation. When Zn precursor was added together with the Cd precursor, Cu(1.94)S-Zn(x)Cd(1-x)S nanodisks were generated. These two-component nanostructures are potentially useful in the fabrication of heterojunction solar cells.

Alloyed (ZnS)x(CuInS2)(1-x) semiconductor nanorods: synthesis, bandgap tuning and photocatalytic properties.

Rod-like nanocrystals of the semiconductor alloy (ZnS)(x)(CuInS(2))(1-x) (ZCIS) have been colloidally prepared by using a one-pot non-injection-based synthetic strategy. The ZCIS nanorods crystallize in the hexagonal wurtzite structure and display preferential growth in the direction of the c axis. The bandgap of these quarternary alloyed nanorods can be conveniently tuned by varying the ratio of ZnS to CuInS(2). A non-linear relationship between the bandgap and the alloy composition is observed. The ZCIS nanorods are found to exhibit promising photocatalytic behaviour in visible-light-driven degradation of Rhodamine B.

Facile noninjection synthesis and photocatalytic properties of wurtzite-phase CuGaS2 nanocrystals with elongated morphologies

In this communication, we present the colloidal preparation of ternary CuGaS2 (CGS) nanocrystals that exhibit elongated morphologies and possess the metastable wurtzite crystal structure. A facile noninjection-based synthetic strategy was utilized wherein dithiocarbamate complexes of copper and gallium were thermally decomposed in the presence of dodecanethiol. The anisotropic CGS nanocrystals were found to display promising photocatalytic behaviour under visible-light illumination.

Temperature and chemical bonding-directed self-assembly of cobalt phosphide nanowires in reaction solutions into vertical and horizontal alignments.

The preparation of vertically or horizontally aligned self-assemblies of CoP nanowires is demonstrated for the first time by aging them in the reaction solution for a sufficient time at 20 or 0 °C. This strategy opens up a way for exploring the controlled self-assembly of various highly anisotropic nanostructures into long-range ordered structures with collective properties.

Ternary cobalt-iron phosphide nanocrystals with controlled compositions, properties, and morphologies from nanorods and nanorice to split nanostructures.

Structural phase-controlled formation of binary Co(2)P and CoP nanocrystals is achieved by reacting cobalt(II) oleate with trioctylphosphine. In the absence of oleylamine, Co(2)P nanowires are formed at both 290 and 320 °C. In the presence of oleylamine, Co(2)P nanorods are formed at 290 °C, and CoP nanorods are formed at 320 °C. With the simultaneous reaction of iron(III) oleate and cobalt(II) oleate with trioctylphosphine in the presence of oleylamine, ternary Co(2)P-type cobalt-iron phosphide nanostructures are produced at both 290 and 320 °C, corresponding to rice-shaped Co(1.5)Fe(0.5)P nanorods and split Co(1.7)Fe(0.3)P nanostructures, respectively. The controlled incorporation of iron into cobalt phosphide can alter the magnetic properties from paramagnetic binary Co(2)P to ferromagnetic Co(2)P-type ternary cobalt-iron phosphide nanostructures. Meanwhile, the time-dependent morphological evolution from small nanodots/nanorods, through seeded growth to unique split nanostructures is demonstrated in one-pot reaction at 320 °C.

Alloyed ZnS-CuInS2 Semiconductor Nanorods and Their Nanoscale Heterostructures for Visible-Light-Driven Photocatalytic Hydrogen Generation.

A promising photocatalytic system in the form of heterostructured nanocrystals (HNCs) is presented wherein alloyed ZnS-CuInS2 (ZCIS) semiconductor nanorods are decorated with Pt and Pd4 S nanoparticles. This is apparently the first report on the colloidal preparation and photocatalytic behavior of ZCIS-Pt and ZCIS-Pd4 S nanoscale heterostructures. Incorporation of Pt and Pd4 S cocatalysts leads to considerable enhancement of the photocatalytic activity of ZCIS for visible-light-driven hydrogen production.

Optimized production of copper nanostructures with high yields for efficient use as thermal conductivity-enhancing PCM dopant

Copper nanostructures with a high yield are synthesized by a controlled disproportionation of CuCl in oleylamine reaction medium without the involvement of strong reducing agents adopted in conventional approaches. The highest copper yield (50%), a maximum theoretical value, is obtained by optimizing both the initial amount of CuCl added to the reaction medium and the reaction temperature. A potential use of the copper nanostructures in greatly enhancing thermal conductivity of a hydrated CaCl2·6H2O salt phase change material (PCM) is further demonstrated. A high thermal conductivity enhancement of the PCM (>50%) is achieved by doping a small amount (<0.2 wt%) of the copper nanostructures. The great enhancement with the use of a very small amount of the copper nanostructures makes the doping cost-effective for practical thermal energy storage applications.

Selective Formation of Ternary Cu-Ge-S Nanostructures in Solution

In this paper, special attention is given to ternary copper germanium sulfides (Cu–Ge–S), which belong to an important class of mixed-metal chalcogenide materials called the copper-based multinary sulfides (CMSs). Like most members of the CMS family, the Cu–Ge–S compounds display enormous potential in energy-related applications especially in their nanostructured forms, but there exists very little research on the preparation of Cu–Ge–S materials in the nanometer size range. Herein, we report a simple noninjection protocol for the selective synthesis of Cu–Ge–S nanomaterials. We show that variations in the solvent environment can lead to different types of Cu–Ge–S nanostructures (i.e., from large, faceted Cu8GeS6 to smaller, irregularly-shaped Cu2GeS3). Our investigation of the growth process revealed interesting formation pathways, which could help advance our understanding of the selective formation of compositionally and structurally diverse multinary materials in solution.