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We have achieved a power conversion efficiency of 16.44% for the ternary polymer solar cell using a wide bandgap copolymer and two non-fullerene acceptors.

Summary The development of advanced catalyst materials capable of efficiently capturing solar energy to drive the beneficial conversion of chemicals is a key part of the blueprint for “liquid sunlight.” Here, highly dispersed ultrafine nano-Au (B/TPTH3@Au) was anchored in situ on B/TPTH3 formed by alternate cross-linking of closo-[B12H12]2− and protonated 2,4,6-tris(4-pyridyl)-1,3,5-triazine. B/TPTH3@Au is an outstanding heterogeneous photocatalyst that converts low-value-added nitroaromatics into high-value-added azoaromatics. Compared with the slow kinetics of previous catalysts, the time required for the conversion of nitroaromatics to azoaromatics driven by B/TPTH3@Au is reduced by at least 10 times. These improvements could be derived from the synergy between the carrier B/TPTH3 (as a stable radical pair) and the nano-gold, including continuous electron transport in the functional carrier B/TPTH3 and the anchoring of highly dispersed ultrafine nano-Au with a strong localized surface plasmon resonance effect.

A new wide-bandgap conjugated D-A polymer denoted as P106 with a medium acceptor dithieno [2,3-e;3'2'-g]isoindole-7,9 (8H) (DTID) unit and strong 2-dodecylbenzo[1,2-b:3,4-b':6,5-b"]trithiophene (3TB) donor units shows an optical bandgap of 2.04 and highest occupied molecular orbital energy level of -5.56 eV. P106 is used as the donor and two nonfullerene acceptors-medium bandgap DBTBT-IC and narrow band Y18-DMO-are used as acceptors for the construction of binary and ternary bulk heterojunction polymer solar cells. The optimized polymer solar cells based on P106 : DBTBT-IC and P106 : Y18-DMO exhibit power conversion efficiencies of 11.76 % and 14.07 %, respectively. The short-circuit current density (22.78 mA cm-2 ) for the P106 : Y18-DMO device is higher than that for P106 : DBTBT-IC (18.56 mA cm-2 ) one, which could be attributed to the more photon harvesting efficiency of the P106 : Y18-DMO active layer. In light of the high short-circuit current densities and fill factors for the Y18-DMO based device and the high value of open circuit voltage of the DBTBT-IC based device, ternary polymer solar cells are fabricated by using ternary active layer (P106 : DBTBT-IC : Y18-DMO) and achieve a power conversion efficiency of 16.49 % with low energy loss of 0.47 eV.

The system is described for the formation of the low-temperature starting plasma flow in the GOL-NB trap. The starting plasma is a target for capturing heating neutral beams. The plasma flow is formed in the arc plasma gun installed in a relatively weak magnetic field. Next, it is compressed in the increasing magnetic field and then transported to a distance of approximately 4 m. The design of the plasma gun is described. Optimization of the operating regimes and scenarios of the system for creating the starting plasma made it possible to reduce the gas load onto the vacuum system of the facility, which resulted in reducing the losses associated with the presence of gas dragged along together with the plasma. The plasma flow at the outlet from the high magnetic field section is increased approximately four times, as compared to the results of the first plasma campaign. It is discussed how the limiters and other intrachamber electrodes affect the plasma flow formation. The achieved plasma flow parameters will be sufficient to start the experiments on plasma heating with the help of neutral beams at the GOL-NB multi-mirror trap in its full-design configuration.

Abstract Nanocomposite networks of surfactant micellar chains and natural bentonite clay nanoplates are studied by rheometry, small-angle neutron scattering, and cryogenic transmission electron microscopy. It is shown that, in an aqueous medium in the presence of a small part of an anionic surfactant, sodium dodecyl sulfate, the molecules of a biodegradable zwitterionic surfactant, oleyl amidopropyl dimethyl carboxybetaine, form micron-length living micellar chains which entangle and form a network possessing well-defined viscoelastic properties. It is found that addition of negatively charged clay nanoplates leads to an increase in viscosity and relaxation time by an order of magnitude. This is explained by the incorporation of the nanoplates into the network as physical multifunctional crosslinks. The incorporation occurs via the attachment of semispherical end-caps of the micelles to the surface of the particles covered with a surfactant layer, as visualized by cryogenic transmission electron microscopy. As the amount of nanoplates is increased, the rheological properties reach plateau; this is associated with the attachment of all end parts of micelles to nanoplates. The developed nanocomposite soft networks based on safe and eco-friendly components are promising for various practical applications.

Data on the morphology of carbon allotrope nanoparticles in an isotactic polypropylene (IPP) matrix are analyzed. They are obtained using the small-angle neutron scattering method and a YuMO spectrometer at the IBR2 reactor of the Frank Laboratory for Neutron Physics, Joint Institute for Nuclear Physics (Dubna, Russian Federation). The fractal dimensionality is calculated, the form is reconstructed, and the geometric dimensions of the obtained particles and aggregates of single-wall carbon nanotubes (SWCNTs) in the IPP volume taken in concentrations of 1.2, 2.6, and 8 wt % are determined using ATSAS software. It is established that nanotubes form fractal nanoobjects with a rough surface in the IPP volume. Composite IPP/SWCNT systems are polydisperse to a significant degree; nanotubes twist into coils and knots and become more densely packed; in the polymer volume, the dimensions of the formed nanoparticles and their aggregates are several times larger than the initial ones used during synthesis. A model of knot formation in polymer materials based on calculating the asymptotic Hopf invariant and the lattice fractal dimensionality is used in this paper to interpret the results and predictions of the possible morphology forming in samples of such a type. The energies and probabilities of knot formation are estimated qualitatively using the Monte Carlo method.

Using scanning tunneling microscopy (STM) and density functional theory (DFT) calculations, we directly determine the spatial and energetic distributions of superatom molecular orbitals (SAMOs) of an Li@C60 monolayer adsorbed on a Cu(111) surface. Utilizing a weakly bonded [Li+@C60] NTf2- (NTf2-: bis(trifluoromethanesulfonyl)imide) salt makes it possible to produce a Li@C60 monolayer with high concentration of Li@C60 molecules. Because of the very uniform adsorption geometry of Li@C60 on Cu(111), the pz-SAMO, populated above the upper hemisphere of the molecule, exhibits an isotropic and delocalized nature, with an energy that is significantly lower compared to that of C60. The isotropic overlapping of pz-SAMOs in the condensed monolayer of Li@C60 results in a laterally homogeneous STM image contributing to the formation of a free-electron-like states. These findings make an important step toward further basic research and applicative utilization of Li@C60 SAMOs.

This work is devoted to studying the structural and morphological properties of a silver colloidal solution obtained by the method of electrical-spark discharge in distilled water. Silver nanoparticles are formed as a result of metal sputtering from the surfaces of silver electrodes, between which a high-voltage electric discharge is generated. The solution is stabilized by forming a layer of anions around the nanoparticles. The structural characteristics of the colloidal solution are studied by small-angle X-ray scattering and transmission electron microscopy. The ionic composition is determined qualitatively using electrospray ionization mass spectrometry, while silver concentration is measured by inductively coupled plasma atomic emission spectrometry.

A turbidimetric photometer with a pulsed mode of operation of a light source is analyzed. The device makes it possible to conduct sedimentation studies of nanoscale object in terms of laboratory background illumination with a study duration of more than 500 hours. The functional diagram of the laboratory device sample is described and experimental surveys of some characteristics are presented.

We study the aggregation of carbon allotrope nanofillers in the matrix of isotactic polypropylene with direct small-angle neutron scattering measurements. With the ATSAS software, we analyzed the d...

A method using a vapor phase approach to formation of a polymer shell on the surfaces of submicron particles (SP) has been investigated. The method is based on the condensation of monomer vapors and their subsequent polymerization on surfaces of charged and dispersed SP. This method makes it possible to vary the thickness of the polymer shell from a few to hundreds of nanometers. This is achieved by choosing the ratio of the flow rates of SP and monomer in two miscible two-phase flows. It is shown that the polymer shell possesses good adhesion to the surfaces of the SP. Apparently, this will make it possible to introduce encapsulated particles, while maintaining the polymer shell, into the polymer matrix of thermoplastics at their softening temperature.

Iron oxide-silica nanocomposites were prepared by sol-gel method using ammonia (NH3), acetic acid (CH3COOH) and hydrochloric acid (HCl) catalysts to generate different pH values for the reaction conditions. As starting precursors, for the silica, respectively, for the iron oxide, tetraethylorthosilicate (TEOS) and iron-III-acetylacetonate were used. The physico-chemical characterization of the materials revealed that the sample obtained with HCl catalyst displays the largest surface area (300 m2/g), the most compact network structure, highest surface roughness, biggest crystallite size (14 nm), magnetization (7 emu/g) and superparamagnetic behavior. These materials were tested for adsorption of Cr6+ and Zn2+ from aqueous solution. Sample M-HCl presented the highest surface area and was further used for adsorption of metal ions. Kinetic, thermodynamic and equilibrium adsorption measurements studies were made for Cr6+ and Zn2+. To establish the material behavior from a thermodynamic point of view, temperature and contact time of adsorption process, activation energy, free energy, of standard enthalpy and entropy were calculated. The kinetic behavior was modelled by pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models and the adsorption characteristics were determined by modelling the experimental data with Langmuir, Freundlich and Sips isotherms.

Hetero[8]circulenes have been shown to be potential charge transport materials in the field-effect devices. In particular, the hole mobility of the octathia[8]circulene thin-film can reach as much as 9 × 10−3 cm2 V−1 s−1 with on/off current ratio of 106 (E. S. Balenkova, R. M. Osuna, F. Rosei, V. G. Nenajdenko and D. F. Perepichka, Chem. Commun., 2008, 5354–5356). In the present paper we carry out a detailed computational study for sixteen crystals of hetero[8]circulenes to gain insight into the design principles of organic semiconductors based on relationships between the crystal packing and charge transport properties. The charge transport parameters and carrier mobilities for the hetero[8]circulenes are systematically explored using the Marcus–Hush electron transfer theory and the Einstein relation. The results show that the O/NH replacement and benzoannelation decreases the reorganization energy during the charge hopping process and increases the electronic coupling within the charge transport pathways, and that sequential replacements of the peripheral sulfur atoms by selenium atoms improve the charge transfer properties. Interestingly, the S/Se substitution induces a conduction inversion; i.e. octathia[8]circulene shows dominating hole transfer and is more suitable as a p-type material, while tetrathiatetraselena[8]circulene and octaselena[8]circulene demonstrate electron-dominated mobility and represent n-type materials. The transfer integrals are sensitive to the stacking organization of the molecules in the crystal, something that is especially clear for regioisomers of tetra-tert-butyl-substituted tetraoxa[8]circulene and azaoxa[8]circulenes. A general trend is that the charge transport within the π–π stacks plays a dominant role for the carrier mobility in the heterocirculene crystals due to the large transfer integrals within such stacking dimer models.

A series of new random terpolymers was synthesized by copolymerization of one electron-donor alkyl-substituted benzodithiophene unit and two electron-acceptor units, diketopyrrolopyrrole (DPP) and bis(4,5-dodecylthiophen-2-yl)-[1,2,5]thiadiazol[3,4-i]dithieno[3,2-a:2',3'-c]phenazine (DF). The influence of the DPP/DF ratio on the thermal, optoelectronic, and electrochemical properties of the terpolymers was investigated using thermogravimetric analysis, UV-Vis spectroscopy, and cyclic voltammetry. The optical properties of the synthesized terpolymers were controlled by varying the DPP/DF ratio. An increase in the DF mole fraction in the polymer chain caused an increase in absorption intensity in the 300‒600 and 600‒1100 nm ranges, while increasing mole fraction of DPP resulted in stronger absorption in the 600‒900 nm range and lower absorption intensity in the 350‒600 nm range. The terpolymers exhibited broad and intense absorption over the spectral range from 300 to 1100 nm. The results demonstrate that random terpolymers with complementary absorption spectra have a great potential for increasing the photocurrent and efficiency of polymer solar cells.

The development of conjugated polymers with wide absorption spectra is imperative to achieve high efficiency in polymer solar cells (PSCs), since most of these polymers usually absorb only a limited range of the solar spectrum. Random terpolymers consisting of three blocks (one electron-donor and two electron-acceptor blocks) are promising p-type polymers for PSCs, because the inclusion of a third block in the polymer macromolecules provides a synergistic effect of physical properties, such as absorption capacity, charge transfer, HOMO/LUMO energy levels, and photovoltaic characteristics. In this regard, we have developed and synthesized random terpolymers consisting of two different chromophores (DPP and BFCTP) with complementary absorption spectra as co-acceptor blocks in conjugated donor–acceptor (D–A) copolymers. Random copolymers exhibit both broad absorption and low HOMO levels favoring short-circuit current and idle voltage in PSCs. It is expected that new terpolymers consisting of one electron-donor unit and two electron-acceptor moieties will make a significant contribution to the development of highly efficient PSCs. It is expected that new ternary copolymers consisting of one electron-donor unit and two electron-acceptor fragments will make a significant contribution to the development of high-performance PSСs.

Temperatures have been identified in the corona hood and streamer of a plasma-chemical reactor during the formation of a polymer film with carbon nanosized particles. A semiempirical procedure has been proposed to estimate these temperatures. It has been shown that in the case where the temperature in the streamer volume is ~600°C and it is ~1400°C in the corona hood, polycrystalline carbon nanoparticles are formed in the plasma-chemical reactor whose agglomerates penetrate into the polymer film.

Currently, the development of stable electrochemical nitrogen reduction reaction (ENRR) catalysts with high N2 conversion activity and low cost to instead of the traditional Haber-Bosch ammonia pro...

For conjugated polymers of interest in photovoltaic applications, control of the bandgap as well as the energy levels of the molecules are of great importance to improve the efficiency and performance of the resulting polymer solar cells. A general tactic for adjusting these properties via modification of the conjugated polymer structure is by using different and chosen molecular groups for copolymerization. This communication presents the synthesis of conjugated donor–acceptor type polymers that have the same benzotrithiophene (BTT) donor and different acceptor units, i.e. DPP and fluoro-carbazole substituted thieno[3,4-b]pyrazine (FCTP) denoted as P(BTT-DPP) (P1) and P(BTT-FCTP) (P2), respectively, and their photovoltaic performance using as donor, and non-fullerene acceptor (PDIF) in the bulk heterojunction active layer. The bandgaps as well as the HOMO and LUMO energy levels are effectively tuned. The P(BTT-FCTPZ) structure exhibits a smaller bandgap as compared to P(BTT-DPP) that results from the lower LUMO energy and higher HOMO energy due to the FCTP unit. Having optimized the active layers, the PSCs that were based on P(BTT-DPP) and P(BTT-FCTPZ gave an overall power conversion efficiency of about 9.77% and 10.97%, respectively, using a wide bandgap PDIF non-fullerene acceptor, and 8.38% and 9.05, respectively, using PC71BM as electron acceptor.

A new oligomeric fluorophore, which combines the advantage of polycyclic aromatic compounds and fluorene structures has been synthesized. The new compound shows necessary film-forming properties, is readily soluble in the majority of organic solvents and emits in the blue range of solar light with maximum at 465 nm. The compound has a rather high quantum yield and can serve as both the electroluminescent dopant and the conducting light-emitting matrix for designing completely soluble blue and white OLEDs by both inkjet printing and spin coating. The new oligomeric fluorophore is a promising example of highly fluorescent oligomer, rarely used class of materials, in contrast to polymers and small molecules. Such oligomers can be useful for future completely soluble OLEDs.

The results of studies into the influence of the thickness of a polystyrene shell applied to surfaces of dispersed corundum (Al2O3) filler particles on the structure and mechanical properties of the composition of an acrylonitrile butadiene styrene plastic are presented. It is shown that the mechanical properties of the composition depend at least on two factors: the interaction between shell molecules and the polymer matrix, and the ratio of shell thickness to the average size of submicron particles of the filler. The change in the mechanical properties of the composition is explained by the decreasing mobility of polymer macromolecules near the encapsulated filler particles due to the increasing adhesion of macromolecules to the polymer shell. It was shown experimentally that the Martens hardness, elastic modulus, tensile strength, and rupture strain can be changed in some range by varying the thickness of the polymer shell on the surfaces of corundum particles.

A structural study of graphene oxide complexes with detonation nanodiamonds (particle size 4–5 nm, positive surface potential) in aqueous suspensions by small-angle neutron scattering is reported. While the pure graphene oxide suspension exhibits a completely planar structure, the grafting of detonation nanodiamond particles results in a slightly curved surface of the graphene oxide flakes. The complexes “graphene oxide–detonation nanodiamonds” washed out from free detonation nanodiamonds show that the effective curvature of the graphene oxide plane is the result of binding of detonation nanodiamonds in the form of planar aggregates.

The series of advanced nanocomposites consisting of Gd2O3 nanoparticles (NPs) embedded into periodic porous SiO2 matrix have been investigated with respect to their structural and magnetocaloric properties. By means of small angle neutron scattering and transmission electron microscopy, regular nanopores organized in the cubic or hexagonal superlattice have been documented. The pores are occupied by the NPs of progressive concentration within the nanocomposite series. All of the examined systems have exhibited extraordinarily high values of magnetic entropy change (up to 70 J kg−1 K−1) at low temperatures with the absence of thermal hysteresis, indicating their perspective utilization in cryogenic refrigeration. Profound analysis of magnetic entropy change data via scaling laws has been applied to the nanocomposite materials for the very first time. With the aid of scaling analysis, conclusions on magnetic properties and phase transition type have been made, even for the conditions unavailable in the laboratory.

Two-dimensional (2D) materials have gained a lot of attention being a new class of materials with unique properties that could influence future technologies. Concomitant computational design and discovery of new two-dimensional materials have therefore become a significant part of modern materials research. The stability of these predicted materials has emerged as the main issue due to drawbacks of the periodic boundary condition approximation that allow one to pass common criteria of stability. Here, based on first-principle calculations, we demonstrate structural stability and instability of several recently proposed 2D materials with pentagonal morphology including the experimentally exfoliated single-layer PdSe2. It is found that an appropriate orientation of the central Pd sublattice with respect to Se2 dimers effectively compensates all mechanical stress and preserves the planar structure of the PdSe2 nanoclusters, while the flakes of all other materials having pentagonal morphology exhibit non-zero curvature induced by excessive interatomic forces. The relative energies of the PdSe2 monolayer and nanotubes per formula unit also confirm that the planar monolayer is a global energy minimum. Like the monolayer, (n,0) PdSe2 tubes are indirect band gap semiconductors with similar band gaps, while (n,n) tubes reveal indirect–direct band gap transitions following the increase of the tube diameter. Small strain energies of large diameter tubes propose their possible experimental realization for various optoelectronic applications.

The electrochemical way of reducing nitrogen to ammonia presents green and economic advantages to dial down irreversible damage caused by the energy-intensive Haber–Bosch process. Here, we introduce an advanced catalyst CB[7]–K2[B12H12]@Au with highly dispersed and ultrafine nano-gold. The CB[7]–K2[B12H12]@Au electrochemically driven ammonia yield and Faraday efficiency is as high as 41.69 μg h−1 mgcat.−1 and 29.53% (at −0.4 V vs. RHE), respectively, reaching the US Department of Energy (DOE) utility index of ambient ammonia production along with excellent cycle stability and tolerance that indicates a high potential of industrial practical value. Experimental results and theoretical calculations show that the key to an excellent electrochemical nitrogen reduction performance lies in the smart design of the CB[7]–K2[B12H12]@Au catalyst combining the stable substrate anchored Au nanoparticles and K+ ions that effectively prevent the hydrogen evolution reaction and polarize *N2 leading to lowering of the rate determining step. This research will promote the further development of electrochemical ammonia production with low environmental impact.

Two donor–acceptor (D–A) conjugated polymers designed on same 8,10-bis(2-octyldodecyl)-8,10-dihydro-9H-bisthieno[2′,3′:7,8;3″,2″:5,6]naphtho[2,3- d]imidazole-9-one donor and dissimilar acceptor uni...

Structural characteristics of nanocomposite series consisting of iron oxide nanoparticles (NPs) embedded in the regular pores of amorphous silica matrix (SBA-15) were investigated by means of small angle neutron scattering (SANS). By virtue of unique neutron properties, insight into the inner structure and matter organization of this kind of systems was facilitated for the first time. Based on rigorous experimental support, fundamental model describing the neutron scattering intensity distribution was proposed by assuming general composite structural features. Model application to SANS data confirmed the presence of iron oxide NPs in the body of examined matrices, providing additional information on their shape, concentration and size distribution. Scattering superposition principle employed in the model conception allows for tailoring its fundamental characteristics, and renders it a potent and versatile tool for a wide range of applications.

Single- and few-layer black phosphorus possesses interesting properties suitable for various optoelectronic applications where graphene cannot be applied due to its vanishing band gap. As phosphorene tends to degrade in environments, various approaches including fluorination have been explored to passivate its surface. Several structures of fluorinated phosphorene have thus recently been reported to demonstrate this approach. On the basis of a combination of first-principles electronic structure calculations and ab initio molecular dynamics, we reconsider the structure of fluorinated phosphorene marking previously reported configurations as thermodynamically unstable with a tendency to decompose spontaneously. We reveal the mechanism of fluorination and propose novel thermodynamically and energetically stable structures containing double fluorine units with enhanced antioxidative stability caused by the fluorination-induced negative electrostatic potential on the surface of phosphorene. The partially fluorinated structure demonstrates almost the same band gap compared to bare phosphorene, making it possible to utilize them in nano-optoelectronic applications.

A new approach was applied to improve the proton conductivity mechanism in perfluorinated membranes for hydrogen fuel cells. The composite short-side chain membranes were modified with functionalized diamond nanoparticles. Carboxylated nanodiamonds embedded in the polymer matrix provide an increase in conductivity at a moderate nanodiamond content, while the mechanical strength of the membranes remains high. The casting method of membranes preparation from solutions in N,N-dimethylformamide allowed saving the general channel structure in membranes at the presence of nanodiamonds, in agreement with neutron scattering data. We propose the formation of additional areas of conductivity, formed controllably, due to nanodiamond particles associated with polymer chains, on the surface of which accelerated diffusion of protons through the hopping Grotthus mechanism from the centers of proton adsorption proceeds with the transition to proton-conducting channels of the matrix covered with sulfonic groups.

Cyclo[18]carbon (C18) is studied computationally at density functional theory (DFT) and ab initio levels to obtain insights into its electronic structure, aromaticity, and adsorption properties on the NaCl surface. DFT functionals with a small amount of Hartree-Fock exchange as well as XMC-QDPT2 calculations fail to determine the experimentally observed polyyne molecular structure revealing a cumulene-type geometry. Exchange-correlation functionals with a large amount of Hartree-Fock ex-change as well as ab initio CASSCF calculations yield the polyyne structure is a ground state while the cumulene structure corresponds to the transition state between the two inverted polyyne structures through the Kekule distortion. The polyyne and the cumulene structures are found to be doubly Hückel aromatic. The calculated adsorption energy of cyclo[18]carbon on the NaCl surface is small (37 meV/C) and almost the same for both structures implying that the surface does not stabilize a particular geometry.

Pyrolyzed derivatives of yttrium bis-phthalocyanine are studied by small-angle neutron scattering, atomic force microscopy and infrared spectroscopy. Completely destroying bis-phthalocyanine molecules, the pyrolysis process forms thermally stable structures, the intrinsic density and packing of which are determined by the temperature. According to neutron data, during low-temperature pyrolysis (below 1000°C), loose chain structures dominate which consist of small carbon clusters; however, during high-temperature pyrolysis (1000–1500°C), carbon globules, creating branched fractal-type aggregates, are formed. In addition to the data on neutron scattering, the surfaces of pyrolyzed films were visualized by atomic force microscopy to study the fractal properties of the surface as a function of the pyrolysis temperature.

Tunable electronic properties of low-dimensional materials have been the object of extensive research, as such properties are highly desirable in order to provide flexibility in the design and optimization of functional devices. In this study, we account for the fact that such properties can be tuned by embedding diverse metal atoms and theoretically study a series of new organometallic porous sheets based on two-dimensional tetraoxa[8]circulene (TOC) polymers doped with alkali or alkaline-earth metals. The results reveal that the metal-decorated sheets change their electronic structure from semiconducting to metallic behaviour due to n-doping. Complete active space self-consistent field (CASSCF) calculations reveal a unique open-shell singlet ground state in the TOC-Ca complex, which is formed by two closed-shell species. Moreover, Ca becomes a doublet state, which is promising for magnetic quantum bit applications due to the long spin coherence time. Ca-doped TOC also demonstrates a high density of states in the vicinity of the Fermi level and induced superconductivity. Using the ab initio Eliashberg formalism, we find that the TOC-Ca polymers are phonon-mediated superconductors with a critical temperature T-C = 14.5 K, which is within the range of typical carbon based superconducting materials. Therefore, combining the proved superconductivity and the long spin lifetime in doublet Ca, such materials could be an ideal platform for the realization of quantum bits.

Although the physicochemical properties of niobium carbide (Nb2C) have been widely investigated, their exploration in the field of photoelectronics is still at the infancy stage with many potential applications that remain to be exploited. Hence, it is demonstrated here that few-layer Nb2C MXene can serve as an excellent building block for both photoelectrochemical-type photodetectors (PDs) and mode-lockers. We show that the photoresponse performance can be readily adjusted by external conditions and that Nb2C NSs exhibit a great potential for narrow-band PDs. The demonstrated mechanism was further confirmed by work functions predicted by density functional theory calculations. In addition, as an optical switch for passively mode-locked fiber lasers, ultrastable pulses can be demonstrated in the telecommunication and mid-infrared regions for Nb2C MXene, and as high as the 69th harmonic order with 411 MHz at the center wavelength of 1882 nm can be achieved. These intriguing results indicate that few-layer Nb2C nanosheets can be used as building blocks for various photoelectronic devices, further broadening the application prospects of two-dimensional MXenes.

It is a challenge to acquire, realize, and comprehend highly emissive phosphorescent molecules. Herein, we report that, using persulfurated benzene compounds as models, phosphorescence can be strongly enhanced through the modification of molecular conformation and crystal growth conditions. By varying the peripheral groups in these compounds, we were able to control their molecular conformation and crystal growth mode, leading to one- (1D), two- (2D), and three-dimensional (3D) crystal morphologies. Two kinds of typical molecular conformations were separately obtained in these crystals through substituent group control or the solvent effect. Importantly, a symmetrical 3,3-conformer exhibits that a planar central benzene ring prefers a 3D-type crystal growth mode, demonstrating high phosphorescence efficiency. Such outcome is attributed to the strong crystal protection effect of the 3D crystal and the bright global minimum (GM) boat-like T1 state of the symmetrical 3,3-conformer. The conformation studies further reveal small deformation of the inner benzene ring in both singlet and triplet states. The GM boat-like T1 state is indicated by theoretical calculations, which is far away from the conical intersection (CI) point between the S0 and T1 potential energy surfaces. Meanwhile, the small energy gap between S1 and T1 states and the considerable spin–orbit coupling matrix elements allow an efficient population of the T1 state. Combined with the crystal protection and conformation effect, the 3,3-conformer crystal shows high phosphorescence efficiency. The unsymmetrical 2,4-conformer conformation with the twisted central benzene ring leads to 1D or 2D crystal growth mode, which has a weak crystal protection effect. In addition, the unsymmetrical conformation has a dark GM T1 state that is very close to the T1–S0 CI point, implying an efficient nonradiative T1–S0 quenching. Thus, weak phosphorescence was observed from the unsymmetrical conformation. This study provides an insight for the development of highly emissive phosphorescent materials. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) National Research Foundation (NRF) Accepted version The research is supported by the Singapore Academic Research Fund (No. RT12/19), the Singapore Agency for Science, Technology and Research (A*STAR) AME IRG grant (No. A1883c0005), the Singapore National Research Foundation Investigatorship (No. NRFNRFI2018- 03), and partially the National Key Research and Development Program of China (No. 2017YFA0207700).

We introduce a new family of 2D materials with unique structure and optoelectronic properties, namely, single-layer gold(I) halides (AuHals). We propose their stability as well as structural, electronic, and optical properties using first-principles calculations. The cleavage energy is found to be similar to that of graphene from graphite, indicating the possibility for mechanical exfoliation. We show that AuHals are stable and have tunable direct (AuBr) and indirect (AuI) band gaps depending on the number of layers. We discuss the possible origin of the giant spin-orbit coupling (SOC) induced conduction band splitting in terms of orbital-decomposed band structure to guide future investigations on the design of materials with highly effective SOC. Exceptionally high excitonic binding energy, high hole mobility, and tunable band gaps indicate that AuHals are promising candidates for optoelectronic devices with excellent performance.

In this work, a measurement setup was assembled to examine if it is possible to adapt a previously created device for measurements with soil samples (using the four-electrode method). Only insignificant modifications were needed for the existing measurement device to perform this kind of measurements. However, accuracy at lower frequencies still needs some improvements. Measurements have shown that for the soils with relatively low permittivity, the distance between the current electrodes should be less than half of the sample's width. Also, the small distance between the voltage electrodes (compared to the distance between the current electrodes) can increase measurement errors.

2D PbS nanoplatelets (NPLs) form an emerging class of photoactive materials and have been proposed as robust materials for high-performance optoelectronic devices. However, the main drawback of PbS NPLs is the large lateral size, which inhibits their further investigations and practical applications. In this work, ultra-small 2D PbS NPLs with uniform lateral size (11.2 ± 1.7 nm) and thickness (3.7 ± 0.9 nm, ≈6 layers) have been successfully fabricated by a facile liquid-phase exfoliation approach. Their transient optical response and photo-response behavior are evaluated by femtosecond-resolved transient absorption and photo-electrochemical (PEC) measurements. It is shown that the NPLs-based photodetectors (PDs) exhibit excellent photo-response performance from UV to the visible range, showing extremely high photo-responsivity (27.81 mA W-1 ) and remarkable detectivity (3.96 × 1010 Jones), which are figures of merit outperforming currently reported PEC-type PDs. The outstanding properties are further analyzed based on the results of first-principle calculations, including electronic band structure and free energies for the oxygen evolution reaction process. This work highlights promising applications of ultra-small 2D PbS NPLs with the potential for breakthrough developments also in other fields of optoelectronic devices.

We have investigated the structural properties, vibrational spectra, and electronic band structures of crystalline cellulose allomorphs and chemically modified cellulose with quantum chemical methods. The electronic band gaps of cellulose allomorphs I$_\alpha$, I$_\beta$, II, and III$_1$ lie in the range of 5.0 to 5.6 eV. We show that extra states can be created in the band gap of cellulose by chemical modification. Experimentally feasible amidation of cellulose I$_\beta$ with aniline or 4,4'- diaminoazobenzene creates narrow bands in the cellulose band gap, reducing the difference between the occupied and empty states to 4.0 or 1.8 eV, respectively. The predicted states 4,4'-diaminoazobenzene-modified cellulose I$_\beta$ fall in the visible spectrum, suggesting uses in optical applications., Comment: 15 pages + 11 pages of supporting information

Inspired by the unusual shapes of the titration curve observed for many surfactants and mixed colloidal systems, we decided to extend the analysis to isothermal titration calorimetric curves (ITC) by paying special attention to potential structural changes in micellar aggregates. In this paper, we used isothermal titration calorimetry in conjunction with Scanning Transmission Electron Microscopy (STEM), Small-Angle Neutron Scattering (SANS) and X-ray Scattering (SAXS) methods support by Monte Carlo and semiempirical quantum chemistry simulations to confirm if the isothermal calorimetric curve shape can reflect micelle transition phenomena. For that purpose, we analysed, from the thermodynamic point of view, a group of cationic gemini surfactants, alkanediyl-&alpha, &omega, bis(dimethylalkylammonium) bromides. We proposed the shape of aggregates created by surfactant molecules in aqueous solutions and changes thereof within a wide temperature range. The results provide evidence for the reorganization processes and the relationship (dependence) between the morphology of the created aggregates and the conditions such as temperature, surfactant concentration and spacer chain length which affect the processes.

—We study the formation mechanism of carbon nanoparticles with simultaneous formation of a polystyrene film in a AC barrier corona discharge at atmospheric pressure. The importance of the research stems from the need to control the allotropic form of carbon nanoparticles, which affects the physical and technical characteristics of polymer films obtained by this method. It is shown that nucleation of polycrystalline onion-like carbon nanoparticle agglomerates is the basis for graphene flake formation in the corona sheath. Graphene flakes form from these nucleation sites in gas discharge streamers owing to the destruction of monomer molecules remaining in the agglomerates of nucleation sites. It was revealed that the allotropic form of such particles is determined not only by the energy—in this case the barrier corona discharge—but also by the ratio of the duration of its exposure to the characteristic destruction and formation times of covalent bonds participating in the particle process.

The structure and mechanical properties of a composition on the basic of polycarbonate filled with three types of dispersed particles (submicron corundum, micron boron nitride, and glass fiber ones) were investigated. It is shown that the method of sample preparation proposed ensures a uniform distribution of filler particles in them. Slight changes in the supramolecular structure of polycarbonate were seen only in the case of introduction of submicron corundum particles. No such changes occurred in the case of micron boron nitride or glass fiber particles in amounts providing an optical transparency no less than 70%, which can be explained by insufficient interaction forces between filler particles and polycarbonate molecules. It is shown that filling polycarbonate with various fillers allowing the retention of its optical transparency does not make it possible to increase its wear resistance and softening temperature. The weight parts of dispersed filler at which the transparency does not decrease below 70 % are ~0.06, ~0.03, and ~1.0% for corundum, boron nitride, and glass fiber particles, respectively.

The electricity provided by solar or wind power can drive nitrogen in the atmosphere, combining with ubiquitous water to form ammonia, and distributed production methods can alleviate the irreversible damage to the environment caused by the energy-intensive Haber-Bosch process. Here, we have designed a novel Ni-doped BCN heterojunction (S/M-BOPs-1) as a catalyst for the electrochemical nitrogen reduction reaction (NRR). The ammonia yield rate and Faraday efficiency in NRR driven by S/M-BOPs-1 reach up to 16.72 μg

Since their discovery in 2011, MXenes (abbreviation for transition metal carbides, nitrides, and carbonitrides) have emerged as a rising star in the family of 2D materials owing to their unique properties. Although the primary research interest is still focused on pristine MXenes and their composites, much attention has in recent years been paid also to MXenes with diverse compositions. To this end, this work offers a comprehensive overview of the progress on compositional engineering of MXenes in terms of doping and substituting from theoretical predictions to experimental investigations. Synthesis and properties are briefly introduced for pristine MXenes and then reviewed for hetero-MXenes. Theoretical calculations regarding the doping/substituting at M, X, and T sites in MXenes and the role of vacancies are summarized. After discussing the synthesis of hetero-MXenes with metal/nonmetal (N, S, P) elements by in situ and ex situ strategies, the focus turns to their emerging applications in various fields such as energy storage, electrocatalysts, and sensors. Finally, challenges and prospects of hetero-MXenes are addressed. It is anticipated that this review will be beneficial to bridge the gap between predictions and experiments as well as to guide the future design of hetero-MXenes with high performance.

For the first time, lonsdaleite-rich impact diamonds from one of the largest Popigai impact crater (Northern Siberia) with a high concentration of structural defects are investigated under hydrostatic compression up to 25 GPa. It is found that, depending on the nature of a sample, the bulk modulus for lonsdaleite experimentally obtained by X-ray diffraction in diamond-anvil cells is systematically lower and equal to 93.3-100.5% of the average values of the bulk moduli of a diamond matrix. Density functional theory calculations reveal possible coexistence of a number of diamond/lonsdaleite and twin diamond biphases. Among the different mutual configurations, separate inclusions of one lonsdaleite (001) plane per four diamond (111) demonstrate the lowest energy per carbon atom, suggesting a favorable formation of single-layer lonsdaleite (001) fragments inserted in the diamond matrix. Calculated formation energies and experimental diamond (311) and lonsdaleite (331) powder X-ray diffraction patterns indicate that all biphases could be formed under high-temperature, high-pressure conditions. Following the equation of states, the bulk modulus of the diamond (111)/lonsdaleite (001) biphase is the largest one among all bulk moduli, including pristine diamond and lonsdaleite.

Oxide films play a significant role in a wide range of fields from catalysis to solar cell materials. CaO films are promising sorbents for many environmentally harmful molecules. Here, we report a systematic investigation of adsorption of CO2, SO2, and H2CO on bulk and Mo-supported CaO(100) films using density functional theory. Significant effects on adsorption energy, charge transfer to the molecules, and degree of the C–O bond activation were demonstrated on Mo-supported CaO films by changing the film thickness, composition, and the strength and direction of an applied external electric field. These findings are relevant for interpreting results from scanning tunneling microscopy of small molecules on metal–supported oxide films and may be useful for better control of the properties of metal oxides, enabling a wide range of potential applications.