A green, regenerative and highly active Cu(0) catalyst derived from waste fibre-based cellulose-supported poly(hydroxamic acid) was synthesized. The surface of the hydrolyzed cellulose was undergone chemical modification through graft co-polymerization using methyl acrylate. Then the poly(methyl acrylate) was further converted into poly(hydroxamic acid) bidentate chelating ligand via Wilhelm Lossen rearrangement in an alkaline hydroxylamine aqueous solution. Finally, the copper was impregnated onto the poly(hydroxamic acid) via the adsorption process forming stable five-member ring complex; Cu(II)NPs@PHA. The Cu(II)NPs@PHA is reduces into Cu(0)NPs@PHA using hydrazine hydride as a reducing agent. The Cu(0)NPs@PHA was fully characterized by FT-IR, FE-SEM & EDX, TEM, ICP-OES, TGA, XRD and XPS analyses. The cellulose-supported Cu(0)NPs@PHA was successfully applied to the Aza-Michael addition reaction with several Michael acceptors and various substituted aryl/heterocyclic/alky amine to afford the corresponding C-N product with excellent yield [aryl amine (50-95%); heterocyclic amine (50-96%); alkyl amine (80-98%)]. The Cu(0)NPs@PHA showed extraordinary stability and it was easy to recover from the reaction mixture and could be reused up to five times without loss of its original catalytic activity.

Semiconductor sol-gel films containing plasmonic nanoparticles are increasingly used in wet analytics (µ-TAS systems) as functional substrates for SERS, as optical elements, photovoltaic and photocatalytic devices. A local change in the structure of such materials with predictable properties of the modified region opens up new possibilities for the creation of integrated circuits and multifunctional systems. Here we considered the mechanism of local modification of TiO₂ thin films structure containing plasmon nanoparticles as a result of laser annealing. The material processing was carried out by scanning with a CW semiconductor laser at a wavelength of 405 nm and at radiation intensity from 35 kW/cm² to 85 kW/cm². The modification region differed in optical characteristics and structural features from the original film. As a result of the laser processing, a heat source was formed that ensured the crystal nucleation and growth of brookite up to an intensity of 55.4 kW/cm². A subsequent increase in intensity led to the transformation of brookite into anatase. The crystal phase formation in the obtained track was accompanied by a change in the relief in its cross section and a decrease of the plasmon resonance peak. The density of the film in the modified region increased, which was accompanied by a decrease in its thickness by 20% from the original film thickness. The disappearance of plasmon resonance in the modified region contributed to a decrease in the absorption capacity and, as a consequence, to a sharp decrease in temperature at the central part of the heat source.

The interaction of quantum emitters with photonic antennas created by nanoscale structures may lead to several interesting phenomena with many important potential applications in current and future technology. There are two distinct regimes of light-matter interaction between a quantum emitter and its modified photonic environment, the weak coupling regime and the strong coupling regime, where the quantum emitter has completely different spontaneous emission response. In the weak coupling regime, an initially excited quantum emitter shows an exponential spontaneous emission dynamics (Markovian response), but the spontaneous decay rate can be markedly different from free-space vacuum, and can be either enhanced or suppressed due to the Purcell effect. In the strong coupling regime, there is a coherent exchange of energy between the quantum emitter and its modified nanophotonic environment, which manifest itself in non-exponential spontaneous emission dynamics (non-Markovian response). We investigate the spontaneous emission dynamics of a two-level quantum emitter in proximity to an atomically thin tungsten diselenide (WSe₂) layer at various distances of the emitter from the layer and various free-space decay rates of the emitter. Depending on the distance and the decay rate value, our studies cover the range of weak to strong coupling regime of the light-matter interaction between the quantum emitter and the electromagnetic continuum modified by the WSe₂ layer. We find that the decay dynamics is Markovian under weak coupling conditions, and it becomes strongly non-Markovian, characterized by oscillatory population emitter dynamics, on the top of the overall population decay, as well as population trapping in the emitter. Besides population evolution, we also discuss the non-Markovian spontaneous emission dynamics using a widely used non-Markovianity measure.

The last three decades, Stimulated Raman Adiabatic Passage (STIRAP) has been proven a robust and high-efficient technique for population transfer in a three-level quantum system and beyond that. As coupled quantum-plasmonic nanostructures are widely used in recent nanophotonics for the superior properties that the coupled structures have over their constituents, a series of studies have analyzed the influence of a spherical metallic nanoparticle, which is a basic plasmonic nanosystem, on coherent population transfer methods in nearby quantum systems. For several recent proposals, it is important to understand the behavior of STIRAP near metallic nanoparticles. Therefore, in this work we present numerical results on the influence of a spherical metallic nanoparticle to the population transfer in a Λ-type quantum system under conditions of STIRAP. For the study of the system’s dynamics, we use the density matrix approach for the quantum system, where the parameters for the electric field amplitudes and the spontaneous decay rates have been calculated using ab initio electromagnetic calculations for the plasmonic nanoparticle. We then present results for the evolution of the populations of the different levels of the quantum system as a function of different parameters, in the presence and the absence of the plasmonic nanoparticle. We find that the presence of the plasmonic nanoparticle and the polarization of the pump and Stokes fields with respect to the surface of the nanoparticle, affect the efficiency of the population transfer inside the three-level quantum system. For the right combination of the values of the free space spontaneous decay rates and the fields intensities, high efficiency population transfer is obtained in the quantum system near a plasmonic nanoparticle using STIRAP process.

The study of nonlinear optical properties of quantum systems, like quantum dots and molecules, near plasmonic nanostructures has attracted significant interest in the past decade. Several nonlinear phenomena have been studied in quantum systems next to plasmonic nanostructures, like second and third harmonic generation, Kerr nonlinearity, four-wave mixing, optical bistability, and nonlinear optical rectification. The latter occurs in asymmetric quantum systems and it can be strongly influenced, enhanced or suppressed, depending on the particular plasmonic nanostructure used. In this work, we theoretically study the nonlinear optical rectification of a polar two-level quantum system, a specific molecule, the Zinc-phalocyanine molecular complex, interacting with an optical field near a gold nanoparticle. Initially, we use the steady-state solution of the density matrix equations for determining the correct form of the nonlinear optical rectification coefficient. We then use ab initio electronic structure calculations for determining the electronic structure of the molecule under study, i.e. the necessary energy differences and the induced and permanent electric dipole moments. We also use ab initio classical electromagnetic calculations for calculating the influence of the metallic nanoparticle on the decay rates of the molecule due to the Purcell effect and on the electric field applied in the molecule in the presence of the metallic nanoparticle. We then use the above to investigate the form of the corresponding nonlinear coefficient in the absence and the presence of the plasmonic nanoparticle for various parameters. We find that the nonlinear optical rectification coefficient can be quite enhanced for specific field polarization and for suitable distance between the molecule and the plasmonic nanoparticle. Also, we observe that high efficiency of this process is obtained for weak field intensity, zero pure dephasing rate and for small value of the transition dipole moment.

The modification of the optical properties of semiconductor quantum dots near plasmonic nanostructures have attracted significant attention in recent years due to the several potential applications of the coupled nanostructures in optoelectronics, biophotonics and quantum technologies, including sensors, light harvesting, quantum information processing and quantum communication, imaging, photocatalysis, solar cells, and others. One of the methods for modifying the nonlinear optical susceptibilities in quantum dots near plasmonic nanostructures uses the change of the spontaneous decay rates of quantum emitters due to the Purcell effect in a tailored nanophotonic environment. In this work, using this idea, we study the modification of the third-order nonlinear optical susceptibilities and specifically the phenomena of degenerate four-wave mixing and third-harmonic generation in a quantum dot that is coupled to a spherical metallic nanoparticle. We find that the strong alteration of the quantum dot’s spontaneous decay rate near the metallic nanoparticle gives strong variation, either enhancement or suppression, of the phenomena of degenerate four-wave mixing and third-harmonic generation for different distances of the quantum dot from the surface of the metallic nanoparticle, depending on the electric dipole direction of the quantum dot. We also show that the degree of enhancement or suppression of the nonlinear optical susceptibilities differs for the studied phenomena and it is stronger for degenerate four-wave mixing than for third-harmonic generation. This work may have important potential applications in the creation of nanoscale photonic devices for various technological applications.

A relatively new area of ​​active research combining nanophotonics, quantum optics and quantum technology is studying the optical properties of complex structures containing plasmonic nanostructures and quantum systems, such as molecules and semiconductor quantum dots. Coherently controlled quantum systems coupled to plasmonic nanostructures are considered active nanophotonic structures and are expected to have important applications in many fields, such as nanotechnology and quantum computing. An important problem studied in these systems is the effect of plasmonic nanostructure on controlled population transfer in the exciton state of the quantum dot, starting from the ground state of the quantum dot. The studies to date on the controlled population dynamics of quantum dots coupled to plasmonic nanostructures have dealt mainly with the preparation of the exciton state by resonant methods, while more recently there has been work on optimal pulses as well. The resonant methods give excitonic population with very high efficiency, but only for a specific combination of pulse width and electric field value. Also, the performance of the resonance methods is quite sensitive to variations in the parameters of the laser fields used. Alternatively, there are very important methods of population transfer and quantum control that are adiabatic that are not sensitive to changes in the parameters of the laser fields. One of these methods is rapid adiabatic passage. This method has been used extensively in isolated quantum dots, both theoretically and experimentally. In the present work, we apply the method of rapid adiabatic passage to a quantum dot coupled to a plasmonic nanostructure, specifically a metal nanoparticle, and examine the excitonic state preparation efficiency for different distances between the quantum dot and the metal nanoparticle. In particular, results for the interaction of the coupled quantum dot – metal nanoparticle structure with linearly chirped Gaussian laser pulses are presented.

Nerve agents (phosphate esters and related phosphorus(V) materials) are among the most noxious chemical compounds known to mankind. Although procedures for their destruction as bulk stockpiles are well known, still the research is open for catalysts for the deactivation of limited amounts of such chemicals, particularly for the use when civilians or military personnel are affected. Surface-passivated gold nanoparticles (AuNPs) have been shown to be among the most powerful catalysts for the cleavage of phosphate diesters (including DNA), nevertheless they have never been used for the hydrolysis of nerve agents. In this work, we report our results on the hydrolysis of simulants p-nitrophenyl diphenyl phosphate (PNPDPP) and dimethyl p-nitrophenyl phosphate (DMNP, methyl paraoxon) by 2-nm AuNPs passivated with metal complexes of ligands bearing 1,4,7 triazanonane and 1,4,7,10 tetraazadodecane macrocycles. PNPDPP was used for a quick screening of a small 28-member library constituted by these AuNP in the presence of metal ions Zn(II), Cu(II), Co(II), Co(III), Eu(III), Yb(III) and Zr(IV). We show that the presence of the amide connecting the cyclic polyamine to the tether is detrimental for catalysis. From the screening of this small library we selected the five best performing catalysts and tested them in the hydrolysis of DMNP which is more similar to the real nerve agents. The results indicate that 2 nm gold nanoparticles passivated with a monolayer of thiols functionalized with macrocyclic ligands cleave quite efficiently nerve agent simulants PNPDPP and DMPN as Zn(II) and Cu(II) complexes at room temperature and physiological pH. The half-lives determined for the hydrolytic process are of the order of a few minutes. The mild conditions employed, and the use of metal ions present in many enzymes make them rather appealing nerve agent detoxification catalysts.

MoS₂ has been demonstrated to be a very promising material in wide variety of applications including nano-electronics, optoelectronics, solar cells, sensors, catalytic applications and so on. However, Controlled growth orientation of MoS₂ thin films is the key requirement to realize their vast number of applications, as material has strong anisotropic properties, in addition chemically active edge sites over inert in-plane MoS₂ flakes is more important for catalytic activities. Thermodynamically, growth of inert in-plane MoS2 is preferred due to less number of active sites on its surface over the edge-sites MoS₂ and that making vertical growth difficult task. Here, we demonstrate for first time the chemical vapor deposition (CVD) of vertically standing molybdenum disulfide (MoS₂) dendrites, with an combination of Molybdenum hexacarbonyl (Mo(CO)₆) and Dimethyl disulfide (C₂H₆S₂) as the novel kind of Mo and S precursors, respectively.

MoS₂ dendrites is a new type of MoS₂ material, SEM and TEM results demonstrated the vertically oriented growth and structure has a tree-like crystal structure with high density of edge terminated MoS₂. Moreover, leaves of those trees has sizes as small as10 nm and consist of MoS₂ few atomics layers . While Raman confirm MoS₂ quality of sheets with 3-4 layers. On optical properties side of dendrites , structure has high absorption cover all visible range of light and strong photoluminescence with wide peak centered around green light due to quantum confinement .

These dendrites usually have unique physical and chemical properties, making them promising for range wide applications in many fields.

Dye removal from manufacturing and textile industry wastewater is one of biggest challenges in plants. The improper disposal of water with residual dyes can contaminate effluents and fresh water sources. In this work, filtration membranes based on reduced graphene oxide (rGO) were fabricated by spray coating method, and its capability to remove dyes from water was evaluated. Graphene oxide was prepared by modified Hummers method and posteriorly reduced with ascorbic acid; a simple and fast spray coating fabrication method was employed to produce stable membranes, which were analyzed in a home-made permeation cell. Raman spectroscopy and scanning electron microscopy (SEM) was able to prove that rGO dispersion was formed by graphene flakes with about 45.9 μm of lateral dimension; X-ray diffraction, SEM and Raman analyses indicate that spray method was efficient in producing stable and uniform filtration membranes; UV-vis absorption spectra of feed and permeation solution indicate that rGO membranes was capable in removing dye from water. By the main results, it is possible to affirm that rGO filtration membranes are an efficient, low-cost, scalable and fast way to treat dyes from wastewater.