Direct fabrication of functional ultrathin single-crystal nanowires from quasi-one-dimensional van der Waals crystals

Micromechanical exfoliation of two-dimensional (2D) van der Waals materials has triggered an explosive interest in 2D material research. The extension of this idea to 1D van der Waals materials, possibly opening a new arena for 1D material research, has not yet been realized. In this paper, we demonstrate that 1D nanowire with sizes as small as six molecular ribbons, can be readily achieved in the Ta2(Pd or Pt)3Se8 system by simple micromechanical exfoliation. Exfoliated Ta2Pd3Se8 nanowires are n-type semiconductors, whereas isostructural Ta2Pt3Se8 nanowires are p-type semiconductors. Both types of nanowires show excellent electrical switching performance as the channel material for a field-effect transistor. Low-temperature transport measurement reveals a defect level inherent to Ta2Pd3Se8 nanowires, which enables the observed electrical switching behavior at high temperature (above 140 K). A functional logic gate consisting of both n-type Ta2Pd3Se8 and p-type Ta2Pt3Se8 field-effect transistors has also been successfully achieved. By taking advantage of the high crystal quality derived from the parent van der Waals bulk compound, our findings about the exfoliated Ta2(Pd or Pt)3Se8 nanowires demonstrate a new pathway to access single-crystal 1D nanostructures for the study of their fundamental properties and the exploration of their applications in electronics, optoelectronics, and energy harvesting

Converting Chemically Functionalized Few-Layer Graphene to Diamond Films: A Computational Study

We propose a new way to produce high-quality films of diamond from chemically functionalized few-layer graphene. Our ab initio calculations show that depending on functionalization few-layer graphene may convert spontaneously in a well-defined way to either cubic or hexagonal diamond films with a specific surface and well-defined properties. We provide specific results for the converting process using H, H₂, F, F₂, H₂O, and NH₃ as adsorbates at different temperatures and pressures

Efficient and Reusable Sorbents Based on Nanostructured BN Coatings for Water Treatment from Antibiotics

Increasing contamination of wastewater with antibiotics used in agriculture, animal husbandry, and medicine is a serious problem for all living things. To address this important issue, we have developed an efficient platform based on a high specific surface area hexagonal boron nitride (BN) coating formed by numerous nanopetals and nanoneedles. The maximum sorption capacity of 1 × 1 cm2 BN coatings is 502.78 µg/g (tetracycline, TET), 315.75 µg/g (ciprofloxacin, CIP), 400.17 µg/g (amoxicillin, AMOX), and 269.7 µg/g (amphotericin B, AMP), which exceeds the sorption capacity of many known materials. Unlike nanoparticles, BN-coated Si wafers are easy to place in and remove from antibiotic-contaminated aqueous solutions, and are easy to clean. When reusing the adsorbents, 100% efficiency was observed at the same time intervals as in the first cleaning cycle: 7 days (TET) and 14 days (CIP, AMOX, AMP) at 10 µg/mL, 14 days (TET, CIP, and AMOX) and 28 days (AMP) at 50 µg/mL, and 14 days (TET) and 28 days (CIP, AMOX and AMP) at 100 µg/mL. The results obtained showed that TET and CIP are best adsorbed on the surface of BN, so TET was chosen as an example for further theoretical modeling of the sorption process. It was found that adsorption is the main mechanism, and this process is spontaneous and endothermic. This highlights the importance of a high specific surface area for the efficient removal of antibiotics from aqueous solutions

Theoretical aspects of WS2 nanotube chemical unzipping

Theoretical analysis of experimental data on unzipping multilayered WS(2) nanotubes by consequent intercalation of lithium atoms and 1-octanethiol molecules [C. Nethravathi, et al., ACS Nano, 2013, 7, 7311] is presented. The radial expansion of the tube was described using continuum thin-walled cylinder approximation with parameters evaluated from ab initio calculations. Assuming that the attractive driving force of the 1-octanethiol molecule is its reaction with the intercalated Li ions ab initio calculations of a 1-octanethiol molecule bonding with Li(+) were carried out. In addition, the non-chemical interactions of the 1-octanethiol dipole with an array of positive point charges representing Li(+) were taken into account. Comparing between the energy gain from these interactions and the elastic strain energy of the nanotube allows us to evaluate a value for the tube wall deformation after the implantation of 1-octanethiol molecules. The ab initio molecular dynamics simulation confirmed our estimates and demonstrated that a strained WS(2) nanotube, with a decent concentration of 1-octanethiol molecules, should indeed be unzipped into the WS(2) nanoribbon

Synthesis and characterization of folate conjugated boron nitride nanocarriers for targeted drug delivery

We have developed advanced folate bonded to boron nitride (BN) nanocarriers with a high potential for targeted drug-delivery. The folic acid (FA) molecules were successfully conjugated to BN nanoparticles (BNNPs) in three consecutive stages: (i) FA pre-activation by N,N'- dicyclohexylcarbodiimide (DCC), (ii) BNNP modification by AgNPs and their further NH2-functionalization with L-Cysteine, and (iii) final conjugation of activated FA to modified BNNPs. To shed a light on the FA-BNNPs binding mechanism, detailed energetic analysis of the atomic structure and stability of the FA-BNNPs system using Density Functional Theory (DFT) calculations was carried out.The results indicated that the FA was successfully bonded with the BNNPs by a condensation reaction between amino groups of Cyst-Ag/BNNPs and carboxyl groups of FA using DCC. Theoretical analysis also demonstrated that the grafting of FA to the surface of BNNP does not affect FA targeting properties