Nicky Savjani

Tin(II) Sulfide (SnS) Nanosheets by Liquid-Phase Exfoliation of Herzenbergite: IV–VI Main Group Two-Dimensional Atomic Crystals

The liquid-phase exfoliation of tin(II) sulfide to produce SnS nanosheets in N-methyl-2-pyrrolidone is reported. The material is characterized by Raman spectroscopy, atomic force microscopy, lattice-resolution scanning transmission electron microscope imaging, and energy dispersive X-ray spectrum imaging. Quantum chemical calculations on the optoelectronic characteristics of bulk and 10-layer down to monolayer SnS have been performed using a quantum chemical density functional tight-binding approach. The optical properties of the SnS and centrifugally fractionated SnS nanosheet dispersions were compared to that predicted by theory. Through centrifugation, bilayer SnS nanosheets can be produced size-selectively. The scalable solution processing of semiconductor SnS nanosheets is the key to their commercial exploitation and is potentially an important step toward the realization of a future electronics industry based on two-dimensional materials.

Nanostructured Aptamer-Functionalized Black Phosphorus Sensing Platform for Label-Free Detection of Myoglobin, a Cardiovascular Disease Biomarker

We report the electrochemical detection of the redox active cardiac biomarker myoglobin (Mb) using aptamer-functionalized black phosphorus nanostructured electrodes by measuring direct electron transfer. The as-synthesized few-layer black phosphorus nanosheets have been functionalized with poly-l-lysine (PLL) to facilitate binding with generated anti-Mb DNA aptamers on nanostructured electrodes. This aptasensor platform has a record-low detection limit (∼0.524 pg mL(-1)) and sensitivity (36 μA pg(-1) mL cm(-2)) toward Mb with a dynamic response range from 1 pg mL(-1) to 16 μg mL(-1) for Mb in serum samples. This strategy opens up avenues to bedside technologies for multiplexed diagnosis of cardiovascular diseases in complex human samples.

Asymmetric MoS2/Graphene/Metal Sandwiches: Preparation, Characterization, and Application

The polarizable organic/water interface is used to construct MoS2 /graphene nanocomposites, and various asymmetrically dual-decorated graphene sandwiches are synthesized. High-resolution transmission electron microscopy and 3D electron tomography confirm their structure. These dual-decorated graphene-based hybrids show excellent hydrogen evolution activity and promising capacitance performance.

MoS2 nanosheet production by the direct exfoliation of molybdenite minerals from several type-localities

Samples of the mineral molybdenite from three classic molybdenum mining localities were examined as a potential source of molybdenum disulfide (MoS2) nanosheets. In all cases, ultrasonication-promoted exfoliation of these samples in N-methylpyrrolidone (NMP) was found to produce MoS2 as dispersed nanosheets with lateral sizes in the range of 200–600 nm and thicknesses between 1 and 10 atomic trilayers. The MoS2 nanosheets obtained were found to be highly crystalline and largely defect-free, but tend to contain small amounts of aggregates on their surfaces. The exfoliated MoS2 dispersions were characterised by UV-Vis spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), (scanning) transmission electron microscopy ((S)TEM) and energy dispersive X-ray (EDX) spectroscopy. This work raises the possibility that mined, unrefined minerals could be a source of low-dimensional MoS2.

The influence of precursor on rhenium incorporation into Re-doped MoS2 (Mo1-:XRexS2) thin films by aerosol-assisted chemical vapour deposition (AACVD)

The molecular precursors [Mo(S2CNEt2)4] (1), [Re(S2CC6H5)(S3CC6H5)2] (2), and [Re2(μ-S)2(S2CNEt2)4] (3) were used to deposit thin films of Re-doped MoS2 at 550 °C by aerosol assisted chemical vapour Deposition (AACVD). ICP-OES was used to quantify the amount of Re dopant in each film which range from ca. 2–17 at% Re, with greater incorporation of Re from films using precursor (3). In general, lightly doped films show evidence of elemental homogeneity and retention of structure from EDX spectroscopy mapping and p-XRD measurements. However, Raman spectroscopy suggests that the MoS2 structure is lost upon heavy doping (ca. >4–7 at% Re) by the disappearance of the E2g and A1g optical phonons of MoS2, which we attribute to the introduction of intralayer Re-Re bonding caused by the larger 5d orbitals of Re. Electron microscopy shows that inclusion of Re dopant atoms also dramatically influences the morphology of the films produced, ranging from lamellar structures to clusters and florets, though at similar doping level the morphologies are similar for films made from both Re precursors.