Dr Sathish Clastinrusselraj Indirathankam

Thin film epitaxy is essential for state-of-the-art semiconductor applications. The combination of different substrates and deposition methods leads to various crystallographic orientation relationships between thin films and substrates, which have a decisive impact on thin film performance. By utilizing pulsed laser deposition, we discovered a very high-index (7 1 ¯ 4) ¿oriented NiO thin film when deposited on r-plane (10 1 ¯ 2) sapphire substrates. The in-plane epitaxial relations are [13 1 ¯] NiO||[1 2 ¯ 10] Sapphire and [1 ¯ 12] NiO||[10 11 ¯] Sapphire , and the lattice mismatch is 3.2% and 0.4% along two directions, respectively. Exchange bias studies by the deposition of Co on NiO (111) and NiO (7 1 ¯ 4) show different behaviors, which may be associated with the spin density and alignment on the surface. Graphical abstract: [Figure not available: see fulltext.].

Starting from sterically encumbered 2,6-di-tert-butylphenyl phosphate (dtbppH2) and co-ligand 3,5-dimethyl pyrazole (dmpz), it is possible to isolate either mono-, di- or tetranuclear copper phosphates by varying the copper source and making attendant changes in the reaction conditions. For example, reaction of copper nitrate with dtbppH2 and dmpz at 60 °C leads to the isolation of the mononuclear copper phosphate [Cu(dtbppH)2(dmpz)(MeOH)2] (1) as the only product. However, the use of copper acetate in place of copper nitrate and conducting the reaction at the room temperature leads to the formation of both dinuclear [Cu(dtbpp)(dmpz)2]2 (2) and tetranuclear [Cu2(dtbpp)(dmpz)2(OAc)(MeO)]2 (3) from the same reaction mixture. Compounds 2 and 3 could be isolated in pure form through fractional crystallization. Copper phosphates 1¿3 have been characterized by both analytical and spectroscopic methods including EPR and magnetic measurements. The molecular structures of all three compounds were established through single crystal diffraction studies. Dc magnetic measurements indicate antiferromagnetic interactions between the metal centres in all the compounds.

In this paper, biocomposites were prepared with carrageenan/fish scale/allopurinol collagen by solution method. Carrageenan fish scale collagen and allopurinol were used at different ratio and the effect of varying the component ratio was investigated by studying the shape, morphology, thermal behavior, and drug release ability of the biocomposites. By varying the carrageenan/collagen ratio, the shape of the biocomposites can be modified. When high amount of carrageenan was used, biocomposites were obtained in film whereas higher content of collagen produced powder form of biocomposites. The characteristics of the biocomposites were studied by Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction Analysis (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Thermal Gravimetric Analysis (TGA), and Differential Scanning Calorimetric (DSC) techniques. The drug (allopurinol) release ability of the biocomposites was evaluated with Ultraviolet¿Visible Spectroscopy (UV¿Vis). Biocomposites in the powder form are different from the biocomposites in the film form by having different shape, morphology, thermal behavior, and drug release ability. However, both are sensitive to pH of solution in drug release process. In addition, the cell toxicity of allopurinol and these biocomposites was evaluated with Vero cells by MTT method. The obtained results confirmed that the biocomposite materials in film shape are promising for the application in biomedicine.

We demonstrate a synthesis of copper nanoparticles decorated over nitrogen-doped mesoporous carbon with different N and Cu contents which exhibit conducting, redox, basic, adsorption, and excellent textural properties. These materials are prepared through a nanotemplating approach by simultaneously encapsulating sucrose, guanidine hydrochloride, and Cu(NO3)2 into the porous channels of mesoporous SBA-15 at a low carbonization temperature of 600 °C. The prepared materials exhibit an ordered mesoporous carbon framework with bimodal pores, decorated with nitrogen and Cu functionalities on the surface of the pores and in the wall structure. The presence of nitrogen functionalities in the porous carbon matrix not only helps to reduce the Cu ions but also stabilizes the nanoparticles and offers redox sites, which are beneficial for adsorption and electrochemical applications. The optimized sample exhibits the highest adsorption capacity of different gases such as CO2 ¿ 22.5 mmol/g at 273 K, H2 -13.5 mmol/g at 77 K at 30 bar and CH4 - 5 mmol/g at 298 K and 50 bar. We also demonstrate that the prepared material shows a high selectivity of adsorption towards CO2 in a mixture of CO2/H2 and CO2/CH4 and it also registers a high supercapacitance of 209 F g-1 at a current density of 1 A g-1 with excellent cyclic stability.

In order to overcome the current energy and environment crisis caused by fossil fuels depletion and greenhouse gas emission, it is indispensable to introduce new, eco-friendly, high-performance materials into energy conversion and storage applications. 2D transition metal oxides (TMOs) are regarded as the promising candidates due to their excellent electrochemical properties. However, their innate poor electronic conductivity greatly restricts their applications in energy conversion and storage. This review discusses and summarizes the developed strategies to overcome the limitation through surface modification including defect engineering, heteroatom incorporation and interlayer doping, as well as hybridization with conductive materials. In addition, a detailed summary of their synthesis and applications in supercapacitors, lithium ion batteries and electrocatalysis is included. Finally, future prospective such as opportunities and challenges is discussed for the successful implementation of 2D TMOs in the field of energy applications.

The isopropylation of naphthalene (NP) was carried out over a BEA zeolite (BEA38; SiO2/Al2O3 = 38) focused on the selectivities for diisopropylnaphthalene (DIPN) and triisopropylnaphthalene (TriIPN) isomers. The isopropylation gave possible eight DIPN isomers including ß,ß- (2,6- and 2,7-), a,ß- (1,3-, 1,6-, and 1,7-), and a,a- (1,4- and 1,5-). The catalysis over BEA works two types of controls: kinetic control operates to form predominantly bulky and unstable a,a-DIPN at low temperatures, and thermodynamic controls work for the predominant formation of the slim and stable ß,ß-DIPN at high temperatures, although the intermediately bulky and stable a,ß-DIPN are the major products through both controls. The enhanced selectivities for ß,ß-DIPN were observed at the early stages of the catalysis in the range of 200-300 °C, which operate under new type of thermodynamic control over fresh catalyst through thermodynamically preferred transition states; however, they decreased with the increase in the selectivities for a,a- and a,ß-DIPN, and converged after prolonged reaction period. The isopropylation of DIPN isomers gives TriIPN isomers: unstable and bulky 1,3,5- and 1,4,6-TriIPN with a,a,ß-substitution, and stable and slim 1,3,7- and 1,3,6-TriIPN with a,ß,ß-substitution. The low temperatures favor the former isomers, whereas the selectivity for the latter isomers increases with increasing reaction temperature. These results indicate that TriIPN isomers principally form under kinetic control at low temperatures, and thermodynamic controls participate in the catalysis at high temperatures. The selectivities for TriIPN isomers kept constant during the reaction at all temperatures: 200, 250, and 300 °C. The catalysis occurs inside the BEA channels and allow even the formation of bulky 1,3,5- and 1,4,6-TriIPN; however, all isomers cannot be isomerized to the others in the channels and on the external surfaces. Severe coke-deposition occurred during the catalysis, particularly in the early stages; however, the catalyst is recovered by the calcination with a small change in catalytic activity.

The isopropylation of naphthalene (NP) over USY zeolite (FAU06, SiO2/Al2O3 = 6) gave all eight possible diisopropylnaphthalene (DIPN) isomers: ß,ß- (2,6- and 2,7-), a,ß- (1,3-, 1,6-, and 1,7-), and a,a- (1,4- and 1,5-). The catalyses were operated under kinetic and/or thermodynamic controls depending on the reaction temperatures since the cavities of FAU topology are wide enough to form all DIPN isomers. Enhanced selectivities for ß,ß-DIPN were observed at the early stages at 200°C, 250°C, and 300°C although the selectivities decreased with the increasing periods, accompanying the increase in a,a- and a,ß-DIPN. The enhancement occurred under new types of thermodynamic controls through thermodynamically preferred transition states to ß,ß-DIPN. Triisopropylnaphthalene (TriIPN) isomers were also formed in the isopropylation. Unstable a,a,ß-TriIPN (1,4,6- and 1,3,5-) was predominantly formed at lower temperatures, however, decreased with the increased of stable a,ß,ß-TriIPN (1,3,6- and 1,3,7-) at higher temperatures. The predominant formation of 1,4,6-TriIPN was also observed in the initial stages in the range of 200°C, 250°C, and 300°C, as reaction period was increased, while the selectivity for the isomer was decreased with concomitant increase in the selectivities for the other isomers. These changes of the selectivities operated under kinetic and/or thermodynamic controls. Large cavities of the zeolite allowed the formation of all TriIPN isomers without steric restriction.

We report on the preparation of ordered mesoporous carbon nitrides (MCN) with a 3D porous structure, tuneable nitrogen contents and basicity and their basic catalytic activities on the Knoevenagel condensation of benzaldehyde with malononitrile. The chemical structure and the nitrogen contents of the materials are finely tuned with the simple adjustment of the calcination temperature from 350 to 550 °C. The samples prepared at 350 and 400 °C exhibit C3N5 structures with 1-amino/imino-1,2,4-triazole moieties, whereas the samples synthesised at 450, 500, and 550 °C possess C3N4 structures with 2-amino/imino-1,3,5-triazine moieties. The materials prepared at the temperature lower than 400 °C show much higher activity than those of the samples prepared at 450, 500 and 550 °C. The change in the catalytic activities of these materials is linked with the change of the structure, nitrogen contents and the functional groups on the surface of the materials prepared at different temperatures. CO2 temperature programme desorption study reveals that 1-amino/imino-1,2,4-triazole moieties in C3N5 samples provide high basicity due to the strain in 5-membered 1,2,4-triazole rings; however, the samples with 1,3,5-triazine moieties have limited basicity which significantly affects the catalytic activity of the material. The optimised C3N5 catalyst shows an enhanced catalytic activity when compared to other mesoporous basic catalysts and C3N4. It is also found that the optimised catalysts are highly stable and can be recycled several times and no major change in the activity is observed.

Current and potential beneficial applications of engineered nanomaterials (ENM) are outweighed by the potential concern of their environmental implications. Understanding the impact of ENM release in the aquatic systems is complicated by the transport of the nanoparticles (NPs) especially in presence of various biotic and abiotic factors. Several attempts have been made to understand the aggregation and sedimentation of ENM in presence of individual factors such as natural organic matter and clay and in presence of salts to address their transportation and fate. The objective of the current study is to compare the effect of abiotic factors on the pH dependent stability and aggregation of TiO2 and CuO NP in a relevant fish embryo (E3) medium as a function of time. The aggregation and the sedimentation are compared in presence of humic acid (HA) alone, montmorillonite clay alone, and their combination. It is observed that in presence of HA, the aggregation of TiO2 NP and CuO NP decreases at pH 6, 8, and 10 and heteroagglomeration of TiO2 NP and CuO NP occurs with clay minerals at pH 2 and 4. It is also found that CuO NP are more stable than TiO2 NP in E3 medium and are perturbed to a lesser extent by the abiotic factors as compared to TiO2. Clay and HA are interesting naturally occurring matter in the aqueous environment that can affect the size, charge, and sedimentation behavior of ENM and thus affect their bioavailability and eventual toxicological fate.

In this article, boundary element method simulations are used to optimise the geometry of silver and gold nanocone probes to maximise the localised electric field enhancement and tune the near-field resonance wavelength. These objectives are expected to maximise the sensitivity of tip-enhanced Raman microscopes. Similar studies have used limited parameter sets or used a performance metric other than localised electric field enhancement. In this article, the optical responses for a range of nanocone geometries are simulated for excitation wavelengths ranging from 400 to 1000 nm. Performance is evaluated by measuring the electric field enhancement at the sample surface with a resonant illumination wavelength. These results are then used to determine empirical models and derive optimal nanocone geometries for a particular illumination wavelength and tip material. This article concludes that gold nanocones are expected to provide similar performance to silver nanocones at red and near-infrared wavelengths, which is consistent with other results in the literature. In this article, 633 nm is determined to be the shortest usable illumination wavelength for gold nanocones. Below this limit, silver nanocones will provide superior enhancement. The use of gold nanocone probes is expected to dramatically improve probe lifetime, which is currently measured in hours for silver coated probes. Furthermore, the elimination of passivation coatings is expected to enable smaller probe radii and improved topographical resolution.