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A facile, two-step procedure was developed to prepare a pure CZTSe (Cu2ZnSnSe4) phase from elemental Cu, Zn, Sn, and Se with the addition of a KI–KCl mixture. During the first step, the mixture charge was reacted at 1000 °C to convert all the metals to selenides. Next, the extracted charge was powdered and again heated to 750 °C to obtain homogeneous grains of CZTSe with a size of 30–100 microns. The main intermediate phase during the synthesis of Cu2SnSe3 was found to dissolve Zn up to 11.5 at% and, without Raman spectroscopy data, this phase could be easily confused with CZTSe because they are not optically distinguishable. On the other hand, the deviation of the Zn content in CZTSe does not exceed ±0.5 at%. [ABSTRACT FROM AUTHOR]

Tin selenide (SnSe), a highly promising layered material, has been garnering particular interest in recent times due to its significant promise for future energy devices. Herein we report a simple solution-phase approach for growing highly crystalline layered SnSe nanoribbons. Polyvinylpyrrolidone (PVP) was used as a templating agent to selectively passivates the (100) and (001) facets of the SnSe nanoribbons resulting in the unique growth of nanoribbons along their b -axis with a defined zigzag edge state along the sidewalls. The SnSe nanoribbons are few layers thick (∼20 layers), with mean widths of ∼40 nm, and achievable length of >1 μ m. Nanoribbons could be produced in relatively high quantities (>150 mg) in a single batch experiment. The PVP coating also offers some resistance to oxidation, with the removal of the PVP seen to lead to the formation of a SnSe/SnO x core-shell structure. The use of non-toxic PVP to replace toxic amines that are typically employed for other 1D forms of SnSe is a significant advantage for sustainable and environmentally friendly applications. Heat transport properties of the SnSe nanoribbons, derived from power-dependent Raman spectroscopy, demonstrate the potential of SnSe nanoribbons as thermoelectric material. [ABSTRACT FROM AUTHOR]

Hybrid capacitors exhibit promise to bridge the gap between rechargeable high‐energy density batteries and high‐power density supercapacitors. This separation is due to sluggish ion/electron diffusion and inferior structural stability of battery‐type materials. Here, a topochemistry‐driven method for constructing expanded 2D rhenium selenide intercalated by nitrogen‐doped carbon hybrid (E‐ReSe2@INC) with a strong‐coupled interface and weak van der Waals forces, is proposed. X‐ray absorption spectroscopy analysis dynamically tracks the transformation from ReO into ReC bonds. The bridging bonds act as electron transport channels to enable improved conductivity and accelerated reaction kinetics. The expanded interlayer‐spacing of ReSe2 layer by INC facilitates ion diffusion and ensures structural stability. As expected, the E‐ReSe2@INC achieves an improved rate capability (252.5 mAh g−1 at 20 A g−1) and long‐term cyclability (89.6% over 3500 cycles). Moreover, theoretical simulations reveal the favorable Na+ storage kinetics can be ascribed to its low bonding energy of −0.06 eV and diffusion barrier of 0.08 eV for sodium ions. Additionally, it is demonstrated that 3D printed sodium‐ion hybrid capacitors deliver high energies/power densities of 81.4 Wh kg−1/0.32 mWh cm−2 and 9992.1 W kg−1/38.76 mW cm−2, as well as applicability in a wide temperature range. [ABSTRACT FROM AUTHOR]

A new method of deborylative selanylation using arylboronic acids and arylseleninic acids gave diaryl selenoethers and diarylselenoxide. The present approach requires only equimolar arylseleninic acid and led selectively to selenoethers or selenoxides depending on the solvent. The method is metal-free, base- or oxidant-free, efficient, and environmentally friendly. [ABSTRACT FROM AUTHOR]

Summary: In this study, 490 nm thin tin selenide thin films were deposited by facile co‐evaporation techniques using Sn and Se sources on a clean glass substrate. The thin films were annealed at moderate annealing temperature followed by characterization and analysis. The thin annealed films possess polycrystalline nature and orthorhombic structure with an average grain size of 130 nm. The band gap assessed from absorption spectra for the highly annealed sample was 1.52 eV. The resistivity and sheet resistance were measured with four‐probe techniques and the sheet resistance was =1.362 × 104 ohm for the highly annealed film. [ABSTRACT FROM AUTHOR]

Nanostructurization-driven reamorphization pathways in glassy arsenic monoselenide g-AsSe originated from both realgar- and pararealgar-type As4Se4 molecules are refined employing ab initio quantum-chemical modeling with atomic cluster-simulation code CINCA. At the basis of calculated cluster-forming energies, most possible molecular-to-network disproportionality scenarios are identified in g-AsSe and parameterized in terms of potential energy landscape. The global equilibrium in melt-quenched g-AsSe is shown to be shifted to under-constrained molecular entities of realgar- and pararealgar-type, supplemented by some network-forming derivatives like optimally-constrained single-broken realgar-type clusters. As a result, the glassy network of melt-quenched g-AsSe tends to be more topologically perfect keeping as many as possible small-ring entities. On the contrary, under externally induced nanostructurization activated by nanomilling, the global equilibrium is shifted to over-constrained reamorphized network built of chain-like entities without small rings stabilized with nearly the same molecular-to-network disproportionality barrier approaching ~ 0.30 kcal/mol. [ABSTRACT FROM AUTHOR]

Abstract The present research is a comparative study that reports an economical and accessible method to synthesize niobium (Nb) and Tantalum (Ta) selenides and tellurides with useful application in the removal of pollutants in textile, paper, and dyeing industries as well as in medical field. In this study, solid-state process was used to generate nanocomposites and various characterization techniques were employed to compare two groups of materials under investigation. Structure, morphology, elemental constitution, and functional groups of synthesized materials were analyzed with XRD, FESEM coupled with EDS, FTIR, and Raman spectroscopy, respectively. HR-TEM images displayed nanoscale particles with tetragonal and monoclinic crystal structures. The optical properties were evaluated in terms of cut-off wavelength and optical band gap using UV-visible spectroscopy. A comparative behavior of both groups of compounds was assessed with regards to their catalytic and microcidal properties. Extracted nanocomposites when used as catalysts, though isomorphs of each other, showed markedly different behavior in catalytic degradation of MB dye in the presence of NaBH4 that was employed as a reducing agent. This peculiar deviation might be attributed to slight structural differences between them. Escherichia coli and Staphylococcus aureus (G –ve and + ve bacteria, respectively) were designated as model strains for in vitro antibacterial tests of both clusters by employing disk diffusion method. Superior antibacterial efficacy was observed for telluride system (significant inhibition zones of 26-35 mm) compared with selenide system (diameter of inhibition zone ranged from 0.8 mm to 1.9 mm). In addition, molecular docking study was undertaken to ascertain the binding interaction pattern between NPs and active sites in targeted cell protein. The findings were in agreement with antimicrobial test results suggesting NbTe4 to be the best inhibitor against FabH and FabI enzymes.

Developing stable and active electrocatalysts is crucial for enhancing the oxygen evolution reaction (OER) efficiency, which sluggish kinetics hinder sustainable hydrogen production. High entropy selenides (HESes) feature with random distribution of multiple metals cations and unique electronic and size effect of Se anion, allowing for precious regulation of their catalytic properties towards high OER activity. In this work, we report a series of high-entropy selenides catalysts with tunable lattice strain for electrocatalytic oxygen evolution. Electrochemical measurements show that the quinary (NiCoMnMoFe)Se x requires only 291 mV to reach 10 mA cm -2 and exhibits a superior stability with negligible current decay during 100 h's continuous operation. By combining experimental measurements and theoretical calculation, the study reveals that the lattice distortion, reflected by the local microstrain near the active site, plays a vital role in boosting the OER activity of HESes., (© 2024 Wiley-VCH GmbH.)

Selenium-containing molecules represent a valuable class of compounds with a variety of applications in chemical and biological fields. Selenated reagents are used as intermediates to introduce functional groups (e.g., double bonds) onto different substrates or in the synthesis of various selenated derivatives. Among the variety of selenium-containing reagents, silyl selenides are frequently used to transfer a selenated moiety due to the smooth functionalization of the Se-Si bond, which allows for the generation of selenium nucleophilic species under mild conditions. While the use of the analogous sulfur nucleophiles, namely silyl sulfides, has been widely explored, a relatively limited number of reports on selenosilanes have been provided. This contribution will focus on the application of selenosilanes as nucleophiles in a variety of organic transformations, as well as under radical and redox conditions. The use of silyl selenides to prepare metal complexes and as selenium precursors of materials for atomic layer deposition will also be discussed.

Predissociation thresholds have been observed in the resonant two-photon ionization spectra of TiSe, ZrSe, HfSe, VSe, NbSe, and TaSe. It is argued that the sharp onset of predissociation corresponds to the bond dissociation energy in each of these molecules due to their high density of states as the ground separated atom limit is approached. The bond dissociation energies obtained are D0(TiSe) = 3.998(6) eV, D0(ZrSe) = 4.902(3)eV, D0(HfSe) = 5.154(4)eV, D0(VSe) = 3.884(3)eV, D0(NbSe) = 4.834(3)eV, and D0(TaSe)= 4.705(3)eV. Using these dissociation energies, the enthalpies of formation were found to be Δf,0KHo(TiSe(g)) = 320.6±16.8 kJ mol-1, Δf,0KHo(ZrSe(g)) = 371.1±8.5 kJ mol-1, Δf,0KHo(HfSe(g)) = 356.1 ± 6.5 kJ mol-1, Δf,0KHo(VSe(g)) = 372.9 ± 8.1 kJ mol-1, Δf,0KHo(NbSe(g)) = 498.9 ±8.1 kJ mol-1, and Δf,0KHo(TaSe(g)) = 562.9±1.5 kJ mol-1. Comparisons are made to previous work, when available. Also reported are calculated ground state electronic configurations and terms, dipole moments, vibrational frequencies, bond lengths, and bond dissociation energies for each molecule. A strong correlation of the measured bond dissociation energy with the radial expectation value, ⟨r⟩nd, for the metal atom is found. [ABSTRACT FROM AUTHOR]

Bismuth oxygen selenide, Bi2O2Se, is a promising thermoelectric material because of its reduced thermal conductivity. In this study, we perform the first-principles calculation and utilize the solution of Boltzmann transport equation in a constant relaxation-time approximation to compute the electronic and thermoelectric properties of Bi2O2Se with O and Se defects. Oxygen vacancies trap bands located inside the band gap of Bi2O2Se, and the compound becomes a conductor. These bands lead to drastic reduction in the Seebeck coefficient. When vacancies are filled by selenide atoms (selenide point defect), the materials return to be a semiconductor and the Seebeck coefficient increases. The increase of S is also found in the system with defects formed by the substitution of oxygen atoms into selenide sites (oxygen point defect) in the pristine compound. The power factor significantly increases during p-type doping compared with that during n-type doping for the selenide point defect. However, differences in the two doping cases are less distinguished for the oxygen point defect. Hence, the selenide point defect, Bi2O2-δSe1+δ with p-type doping, is an effective way to increase the power factor and eventually the thermoelectric efficiency of Bi2O2Se. [ABSTRACT FROM AUTHOR]

The construction of cluster-based crystalline chalcogenide structures through the traditional solvothermal method relies on synergistic control of precursors, template cations and auxiliary solvents. Generally, the combination of metal precursors plays a crucial role in controlling the size of clusters, while organic templates and auxiliary solvents usually contribute to the type of clusters and architecture of the framework. Decades of synthetic efforts have been mainly devoted to expanding organic amine templates for constructing new structures. However, the important role of auxiliary solvents in enriching the chalcogenide family is usually disregarded. Reported here are several new crystalline In–Se compounds (ISP-1 to 4) with different dimensions, obtained by elaborately regulating auxiliary solvents under the direction of the same organic template, piperidine. Of these four structures, ISP-1 is constructed by irregular supertetrahedral clusters, giving a novel 2D structure with a corner-shared single Se atom and In2Se3 five-member ring as linkers; ISP-2 has a 1D structure composed by interlinked In2Se3 five-member rings; ISP-4 is constructed by supertetrahedral T2 clusters exhibiting an uncommon zeolite-like mog network. [ABSTRACT FROM AUTHOR]

Indium selenides (InSe and In2Se3) have garnered enormous interest owing to their favourable carrier mobility and high photoresponsivities, exhibiting great application potential in high performance photovoltaic and optoelectronic devices. Selective synthesis of InSe and In2Se3 materials from the same molecular precursor is a challenging task. In this study, we prepared and characterized an air and moisture stable tris(4,6-dimethyl-2-pyrimidylselenolato)indium(III) complex, as a single source molecular precursor, to synthesize stoichiometric indium selenides (InSe and In2Se3) in the nano-regime with precise control, through proper choice of the reaction solvents. The crystal structure, phase purity and composition of the materials were determined by pXRD and EDS analysis, whereas the electron microscopic studies revealed that the reaction conditions have a profound effect on the morphology of the nanostructures. The UV-DRS analysis showed a blue shift relative to the bulk band gap and falls in the range suitable for solar cell applications. Finally, efficient photoresponsitivity was achieved in the as-prepared cubic InSe and hexagonal In2Se3 nanocrystal-based prototype devices. [ABSTRACT FROM AUTHOR]

Engineering of structure and composition is essential but still challenging for electrocatalytic activity modulation. Herein, hybrid nanostructured arrays (HNA) with branched and aligned structures constructed by cobalt selenide (CoSe2) nanotube arrays vertically oriented on carbon cloth with CoNi layered double hydroxide (CoSe2@CoNi LDH HNA) are synthesized by a hydrothermal‐selenization‐hybridization strategy. The branched and hollow structure, as well as the heterointerface between CoSe2 and CoNi LDH guarantee structural stability and sufficient exposure of the surface active sites. More importantly, the strong interaction at the interface can effectively modulate the electronic structure of hybrids through the charge transfer and then improves the reaction kinetics. The resulting branched CoSe2@CoNi LDH HNA as trifunctional catalyst exhibits enhanced electrocatalytic performance toward oxygen evolution/reduction and hydrogen evolution reaction. Consequently, the branched CoSe2@CoNi LDH HNA exhibits low overpotential of 1.58 V at 10 mA cm−2 for water splitting and superior cycling stability (70 h) for rechargeable flexible Zn‐air battery. Theoretical calculations reveal that the construction of heterostructure can effectively lower the reaction barrier as well as improve electrical conductivity, consequently favoring the enhanced electrochemical performance. This work concerning engineering heterostructure and topography‐performance relationship can provide new guidance for the development of multifunctional electrocatalysts. [ABSTRACT FROM AUTHOR]

WSeCl4 was obtained in good yield by heating WCl6 and Sb2Se3in vacuo. Green crystals grown by sublimation were shown by single crystal X-ray structure analysis to contain square pyramidal monomers with apical W＝Se, and powder X-ray diffraction (PXRD) analysis confirmed this to be the only form present in the bulk sample. Density functional theory (DFT) calculations using the B3LYP-D3 functional replicated the structure, identified the key bonding orbitals, and were used to aid assignment of the IR spectrum of WSeCl4. Reaction of WSeCl4 with ligands L gave [WSeCl4(L)] (L = MeCN, DMF, thf, py, OPPh3, 2,2′-bipy, SeMe2, SenBu2), whilst the dimers [(WSeCl4)2(μ-L–L)] were formed with L–L = Ph2P(O)CH2P(O)Ph2, 1,4-dioxane and 4,4′-bipyridyl. The complexes were characterised by microanalysis, IR and 1H NMR spectroscopy, and single crystal X-ray structures determined for [WSeCl4(L)] (L = OPPh3, MeCN, DMF) and [(WSeCl4)2(μ-L–L)] (L–L = 1,4-dioxane, 4,4′-bipyridyl). All except the 2,2′-bipy complex, which is probably seven-coordinate, contain six-coordinate tungsten with the neutral donor trans to W＝Se. Alkylphosphines, including PMe3 and PEt3, decompose WSeCl4 upon contact, forming phosphine selenides (SePR3). In contrast, the selenoether complexes [WSeCl4(SeMe2)] and [WSeCl4(SenBu2)] were isolated and characterised. The crystal structure of the minor W(VI) by-product, [(WSeCl4)2(μ-SeMe2)], was determined and using SMe2, a few crystals of the W(V) species, [{WCl3(SMe2)}2(μ-Se)(μ-Se2)], were obtained and structurally characterised. The isolated W(VI) complexes are compared with those of WOCl4 and WSCl4 and the combination of experimental and computational data are consistent with WSeCl4 being a weaker Lewis acid and its complexes significantly less stable than those of the lighter analogues, especially in solution. Low pressure chemical vapour deposition (LPCVD) using [WSeCl4(SenBu2)] in the range 660–700 °C (0.1 mmHg) produced highly reflective thin films, which were identified to be WSe2 by grazing incidence X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. XRD analysis of the thinner films revealed them to be highly oriented in the <00l> direction. [ABSTRACT FROM AUTHOR]

Selenides are important structural motifs with a broad range of biological activities and versatile transformational abilities. In this study, a novel and mild method was developed for the facile synthesis of asymmetric selenides under metal-free conditions. The key features of this reaction include good functional-group tolerance, the use of readily available reagents and cheap, low-toxicity solvent, and amenability to gram-scale synthesis. The results of preliminary radical-trapping experiments and a kinetic isotope effect study support a radical process. [ABSTRACT FROM AUTHOR]

The realization of carbon‐neutral energy is regarded a prime challenge as the environment and energy have become two key issues facing modern society. Here, synergistically interfaced transition metal selenides are studied for hydrogen production via urea electrolysis with concurrent environmental treatment. Extremely low overpotentials of 210 mV, 250 mV, and 1.41 V vs. RHE were observed at 100 mA cm−2 for HER, OER and UOR, respectively with a 98.3 % faradaic efficiency. A notably low cell voltage of 1.6 and 1.84 V was required at 200 mA cm−2 for urea and water electrolysis, respectively along with a remarkably stable performance for 4 days. Additionally, A 1.45‐fold increase in H2 production rate was observed for urea electrolysis [26.6 μmol min−1] when compared with water electrolysis [18 μmol min−1] decreasing the power consumption by 37 %. Real human urine electrolysis was conducted with excellent performance requiring a cell voltage of only 1.9 V at 200 mA cm−2, attributed to the synergistic intermediate‐active site interaction, improved charge transfer capability, and slow surface transformation‐induced activation. [ABSTRACT FROM AUTHOR]

Metal-free C–Se cross-couplings via the formation of electron-donor–acceptor (EDA) complexes have been developed. The visible-light induced reactions can be applied for the synthesis of a series of unsymmetrical diaryl selenides employing aryl bromides, aryl iodides as well as aryl chlorides under mild reaction conditions. The scale-up was readily achieved. UV-Vis spectroscopy measurements provide insight into the reaction mechanism. [ABSTRACT FROM AUTHOR]

Nanotechnology has become one of the most widely used technologies in translational research and may significantly impact the future of healthcare. Because of their distinctive physicochemical characteristics, nanoparticles (NPs) have diverse applications in all areas of science including biomedicine, agriculture, biolabeling, catalysis, electronics, sensors, and fiber optics. Recently, green synthesis technology, as a reliable and eco-friendly method, has been taken into consideration for synthesizing a wide range of nanomaterials of desired sizes, shape, and functionalities. In this regard, zinc selenide nanoparticles (ZnSe- NPs) as a semiconductor nanostructure with low toxicity and high luminescence features have potential applications in different research fields like optoelectronic devices, laser solar cells, and, particularly in medical and biological sciences. ZnSe NPs can be synthesized by various chemical methods, including solgel, solvothermal, hydrothermal, wet chemical, and green and biological synthesis approaches. In this study, we have reviewed the green chemical or biological ZnSe nanoparticles synthesis as eco-friendly methods. Also, we have discussed the biological applications of ZnSe nanoparticles, including antibacterial activity, cytotoxicity effect, biomedical imaging and, drug delivery. [ABSTRACT FROM AUTHOR]

Coating systems for titanium implants comprising TiO2 nanotubes and Se alloys (Cu2Se-pTNT and Ag2Se-pTNT) were developed in our previous work to prevent bacterial infections at the bone-implant interface. TiO2 nanotubes were grown on a Ti-based material by anodization and Cu2Se or Ag2Se alloys were incorporated by pulse electrodeposition. Preliminary in vitro investigations identified promising antibacterial properties. Two possible mechanisms of antibacterial activity are the release of bactericide metal ions and/or the formation of reactive oxygen species (ROS). In this work, the activity of the Se alloys for both effects was investigated by electrochemical measurements. Cu2Se and Ag2Se alloys were characterized by rotating disk electrode (RDE) measurements to investigate the reaction pathway for the oxygen reduction reaction (ORR) which may lead to peroxide species. RDE measurements, performed at potentials between 0 and − 0.8 V versus Ag/AgCl (sat. KCl) in an isotonic electrolyte (9 g L−1 NaCl, pH 7) at different oxygen partial pressures, showed that both, Cu2Se and Ag2Se, catalyze the two-electron transfer indicative of an indirect ORR with formation of H2O2 as an intermediate product. For comparison, bare Cu and Ag electrodes were also investigated. Under anodic conditions, selenide alloys slowly release antibacterial metal ions in a controllable and healthy amount for the body. The results demonstrate that these coatings can trigger antibacterial activity by two different mechanisms under both reducing and oxidizing conditions. [ABSTRACT FROM AUTHOR]

• Low cost and stable solution-processed inorganic VOx hole transport layer for Sb 2 Se 3 solar cells for the first time. • Close space sublimation deposition of a thickness of 500 nm Sb 2 Se 3 absorber material. • Sb 2 Se 3 with VOx hole transport layer achieve a power conversion efficiency ∼6.3%. • VOx could improve the open-circuit voltage of Sb 2 Se 3 solar cells. Antimony selenide (Sb 2 Se 3) is a promising light absorber material for solar cells because of its superior photovoltaic properties. However, the current performance of the Sb 2 Se 3 solar cell is much lower than its theoretical value (∼32%) due to its low open-circuit voltage (V OC). In this paper, we have demonstrated inorganic vanadium oxides (VO x) as a hole transport layer (HTL) for Sb 2 Se 3 solar cells to enhance efficiency through the V OC improvement. Here, a solution-processed VO x through the decomposition of the triisopropoxyvanadium (V) oxide is deposited on the Sb 2 Se 3 absorber layer prepared by close-spaced sublimation (CSS). With VO x HTL, the built-in voltage (V bi) is significantly increased, leading to improved V OC for the Sb 2 Se 3 solar cell devices. As a result, the efficiency of the device increases from an average efficiency of 5.5% to 6.3% with the VO x. [ABSTRACT FROM AUTHOR]

The reaction between Oxone® and various di(hetero)aryl or alkyl diselenides enables the formation of an electrophilic selenium species in situ capable to induce the oxyselenocyclization of 2‐allylphenols. This versatile and safe protocol was explored to combine two privileged scaffolds into the structure of products: the 2,3‐dihydrobenzofuran core and an organoselenium moiety. Fifteen 2‐[(organoselanyl)methyl]‐2,3‐dihydrobenzofurans were produced, broadening considerably the number of known examples of this hybrid compound. Moreover, preparation of sulfur and tellurium 2,3‐dihydrobenzofurans derivatives was also successfully demonstrated. [ABSTRACT FROM AUTHOR]

The synthesis and the study of organoselenium compounds have received much attention over the past decades. Selenium‐containing organic molecules are widely used in organic synthesis, materials science, and medicinal chemistry. Selenium – and more specifically the amino acid selenocysteine, bearing a selenol (SeH) moiety – is present in at least 25 human protein families, whose biological functions have not been completely identified. Amongst the variety of organoselenium compounds, selenols are a versatile class of molecules easily undergoing a broad array of useful transformations. Because of the unique properties of the SeH group, selenol chemistry has important applications in chemical sciences, spanning from organic synthesis to materials chemistry and biology. This review summarises currently available methodologies for the synthesis of selenols and highlights applications of selenols in chemical sciences and biology. [ABSTRACT FROM AUTHOR]

The development of hydrogen production via environment-friendly and efficient electrochemical water splitting technology leans heavily on the exploitation of highly active and durable oxygen evolution reaction (OER) electrocatalysts. Herein, nanocoral-like cerium-activated cobalt selenide (Ce-CoSe2) nanocomposites to enhance the OER catalytic activity have been successfully prepared by one-pot hydrothermal route via simply altering the cerium content. Owing to the ingenious introduction of cerium, as-prepared Ce-CoSe2 electrode displays remarkable OER performance in comparison with CoSe2. The nanocoral-like Ce-CoSe2 catalyst prepared under optimal condition just needs low overpotential of 276 and 398 mV at 10 and 50 mA cm−2, respectively. Additionally, it attains the current density of 255 mA cm−2 at the potential of 2.0 V vs. RHE, and shows long-term stability during OER. This work offers a simple and feasible pathway for the design and construct of metal dichalcogenides for green and renewable hydrogen production by electrocatalytic water splitting. [ABSTRACT FROM AUTHOR]

The results of this study show that disilathiane is an effective mediator in the synthesis of alkyl aryl sulfides with disulfides and alkyl carboxylates. Mechanistic studies suggest that disilathiane promotes cleavage of the sulfur–sulfur bond of disulfides to generate thiosilane as a key intermediate. Diselenides were also applicable to this transformation to produce the corresponding selenides. [ABSTRACT FROM AUTHOR]

A mild copper-catalyzed four-component selenosulfonylation of alkynes, cycloketone oxime esters, DABCO (SO2)2 and diselenides has been developed. This method enables the rapid assembly of β-cyanoalkylsulfonylated vinyl selenides in moderate to good yields. Advantages of this protocol include a broad substrate scope, good functional group tolerance and the late-stage functionalization of complex molecules. Moreover, the potential utility of this methodology is demonstrated through simple oxidation of the products to access synthetically important alkynyl sulfones. Mechanistic studies suggest that a cyanoalkylsulfonyl radical intermediate is involved in this process. [ABSTRACT FROM AUTHOR]

We have developed novel hydrothermal (HT) and hydrothermal microwave (HTMW) processes for the synthesis of nanocrystalline cadmium selenide via reduction using glucose and sodium sulfite. The materials thus obtained have been characterized by X-ray diffraction, CHNS analysis, and electron microscopy. The results demonstrate that they crystallize with a cubic and/or hexagonal symmetry and are nanocomposites containing 14 to 60 wt % organics. Varying synthesis conditions (temperature, composition of the starting mixture, and reaction time) allows one to obtain samples with sizes of coherent scattering regions from 6 to 80 nm. The use of the HTMW process reduces the synthesis time to 15 min in comparison with HT synthesis. The electrical resistance of nanocomposites, measured by the microwave loss method is 10–4 to 10–3 Ω cm, which is considerably lower than the resistivity of corresponding CdSe crystals. The data obtained in this work can be accounted for by the presence of carbon-containing components of the composite, which constitute a shell of particles. The increase in the cross-sectional area of "carbon channels" with decreasing nanoparticle size leads to an increase in the electrical conductivity of the material. [ABSTRACT FROM AUTHOR]

Epitaxial growth of SnSe was studied using pulsed laser deposition on three kinds of singlecrystalline substrates, MgO (100), NaCl (100), and SrF2 (100), along with silica glass. For polycrystalline SnSe grown on glass, we found that a 20% Se-rich polycrystalline target is effective for obtaining stoichiometric SnSe films. The crystal structure of all the obtained films was the same as that of bulk SnSe, and the optimum temperatures for epitaxial growth were 400-500 °C, where the highest temperature was limited by re-evaporation. All the epitaxial films exhibited an a-axis orientation. For in-plane epitaxial structures, a quasi cube-on-cube heteroepitaxy was observed for MgO, whereas a 45°-rotated heteroepitaxy was observed for NaCl and SrF2, which can be explained by in-plane lattice matching. The anisotropic lattice mismatching and thermal expansion explain the compressive strain induced along the in-plane c-axis and the tensile strains along the in-plane b-axis and the out-of-plane a-axis. The epitaxial films on NaCl exhibited the best crystallinity, but the highest hole mobility of 60 cm2/(V s) was obtained on MgO. The indirect optical gap of the best films was determined to be 0.8 eV. Plausible interface models were proposed based on density functional calculations. [ABSTRACT FROM AUTHOR]

This paper reports on the antibacterial properties of bismuth selenide prepared by cost effective methods; sol–gel and hydrothermal method for which 2:3 of bismuth nitrate pentahydrate and elemental selenide are used. X-ray diffraction (XRD), ultraviolet–visible absorption (UV–Vis.) and Fourier-transform infrared spectroscopy (FTIR) were carried out to characterize the synthesized samples. Structural analysis of synthesized samples using XRD revealed that the grain size of samples is nanosized and possess crystalline nature showing orthorhombic structure (sol–gel) with average grain size of particles to be 24.05 nm (standard deviation 4.55 nm), and rhombohedral (hydrothermal) with average grain size of particles to be 12.20 nm (standard deviation 3.3 nm). UV–Vis analysis revealed the absorption region for Bi2Se3 nanoparticles and their corresponding energy bandgap between 1.47eV and 1.74 eV range. FTIR spectrum shows the region of vibrational stretching between 600cm-1 and 1000 cm−1 that corresponds to Bi and Se bonding. Disk diffusion method was used to check the antibacterial activity successfully against gram-positive bacteria S. aureus and gram-negative bacteria E. coli. [ABSTRACT FROM AUTHOR]

Bis[(E)-2-bromovinyl] selenide enters cross coupling with terminal acetylenes in the presence of a Pd/CuI catalyst at room temperature. The reaction involves both the bromine atom and the selanyl function and leads to both substituted bis(but-1-en-3-ynyl) selenides and enediynes with complete retention of the configuration of the parent selenide. [ABSTRACT FROM AUTHOR]

Electrocatalytic overall water splitting with renewable energy input has been recognized as one of the most promising approaches to produce clean H2. While expensive catalysts and low energy conversion efficiency limited industrial application of this method. Herein, we reported a cost-effective and efficient water splitting electrocatalyst prepared by one-step thermo-selenation from readily available stainless steel foam. The activity of the synergistic multi-metal catalyst has been greatly improved, showing overpotentials of 237 mV and 263 mV for HER and OER, respectively, to achieve catalytic current density of 10 mA·cm−2 in 1.0 M KOH. And the overall water splitting was achieved at 1.73 V. The stability of the composite catalyst is very high. These results showed that selenation of stainless steel was an promising method for large-scale preparation of overall water splitting electrocatalyst. [ABSTRACT FROM AUTHOR]

Using elemental selenium as an electrode, the redox-active Cu2+/Cu+ ion is reversibly hosted via the sequential conversion reactions of Se → CuSe → Cu3Se2 → Cu2Se. The four-electron redox process from Se to Cu2Se produces a high initial specific capacity of 1233 mA h g−1 based on the mass of selenium alone or 472 mA h g−1 based on the mass of Cu2Se, the fully discharged product. [ABSTRACT FROM AUTHOR]

A scalable in-situ electrodeposition technique is developed to synthesize cobalt selenide (Co 0.85 Se) nano-arrays with remarkable conductivity and high catalytic activity on carbon-modified separator targeted advanced Li–S batteries. Our devised in-situ electrodeposition technique might pave a new way to the controllable design of highly active electrocatalysts for high-performance Li–S batteries. [Display omitted] Lithium–sulfur batteries (LSBs) have attracted much attention due to their high theoretical specific capacity, energy density and low cost. However, the commercial application of LSBs is hindered due to the lithium polysulfide (LiPS) shuttle as well as the sluggish reaction kinetics. Herein, cobalt selenide (Co 0.85 Se) nanowire arrays have been constructed on a carbon-modified separator by an in-situ electrodeposition technique without any other post-treatments such as coating with other ancillary materials. The introduced three-dimensional (3D) conductive carbon layer comprising of carbon nanotube (CNT) and acetylene black (AB) not only serves as the effective support for Co 0.85 Se (CS) but also builds a hierarchical structure to promote the e− transfer. The as-obtained CS-CNT/AB presents a strong anchoring effect on LiPSs and high electrocatalytic activity for sulfur reaction kinetics. As a result, the LSBs inserted with electrodeposition-enabled CS modified separator exhibit an outstanding rate capability (1560.4 mAh g−1 at 0.1 C) and relatively low capacity decay of only 0.068% per cycle over 500 cycles at 2.0 C. This study provides a promising strategy to realize the rational construction of high-efficiency and long-life LSBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe-doped Cu 3 Se 2 nanoparticles synthesized using the sonochemical route. • Effect of Fe concentrations investigated on the physical features of Cu 3 Se 2 nanoparticles. • The optoelectronic performance was enhanced by Fe concentrations due to improvements in the carrier concentration. • A correlation between physical properties and optoelectronic performance was presented. This research presents the effect of different concentrations of iron (Fe) as dopants on the physical properties of the copper selenide (Cu 3 Se 2) nanoparticle (NPs). The physical properties of the Cu 3 Se 2 NPs were investigated using structural, morphological, and optical analysis. The results revealed that the Fe concentrations change the crystallite size (from ∼8 to 44 nm) and strain (from ∼0.0007 to 0.0030). Fe-doped Cu 3 Se 2 NPs showed a higher optical energy band gap in comparison to the un-doped sample (1.80 eV). The films prepared by green binder (ethyl cellulose) indicated that the sample with minimum Fe concentration presents the highest carrier concentration (9.56e+18 cm−3) and lowest ideality factor (2.02) amounts. The electrical study shows space charge limited current (SCLC) mechanism in Fe-doped Cu 3 Se 2 NPs that is not observed in un-doped sample. Using this mechanism, the highest carrier mobility (16.22 cm+2V−1s−1) obtained for sample with the lowest amount of Fe concentrations. [ABSTRACT FROM AUTHOR]

Heptamethine cyanine dyes (HCDs) feature a large molar extinction coefficient, a high fluorescence quantum yield, and an adjustable structure, with maximum absorption and emission wavelengths located in the near-infrared region. Thanks to these excellent features, the HCDs have been widely used in biological imaging, ion detection, new energy, and many other fields. However, the unique structure of the HCDs brings some defects, such as poor hydrophilicity and low photostability. Many scholars have been striving to expand the application of the HCDs in biological analysis by improving properties like spectral properties, hydrophilicity, photostability, and fluorescence quantum yield. This paper thoroughly reviews the advances of structural modification in the sites of terminal heterocycles (indole, benzothiazole, benzoxazole and benzoselenide) and polymethine chains (straight chain or rigid bridged ring), and introduces the influences of functional materials over the features of the HCDs. Finally, the authors predicted the development trend of the HCDs. [ABSTRACT FROM AUTHOR]

An efficient protocol for the construction of valuable β-hydroxy aryl selenides from easily available arylamines, elemental selenium, and epoxides through a transition-metal-free radical process is described. A wide variety of β-hydroxy aryl selenides were obtained in good to excellent yields with excellent stereo- and regioselectivity. In this reaction, two C–Se bonds can be built along with the cleavage of a C–N and C–O bond, demonstrating the high step economy and efficiency of this approach. [ABSTRACT FROM AUTHOR]

Herein, we report on the rhodium‐catalyzed reaction of triazoles with acyl selenides. Under thermal reaction conditions and in the presence of a rhodium catalyst, a rapid 1,3‐difunctionalization reaction occurs to provide valuable α‐seleno enamides with high stereoselectivity and broad functional group tolerance, which was demonstrated in 35 examples with up to 95% yield. Computational calculations suggest a reaction pathway that gives a direct access to the 1,3‐difunctionalization without intermittent formation of ylide intermediates. [ABSTRACT FROM AUTHOR]

We report a layered ternary selenide BaPt4Se6 featuring sesqui-selenide Pt2Se3 layers sandwiched by Ba atoms. The Pt2Se3 layers in this compound can be derived from the Dirac-semimetal PtSe2 phase with Se vacancies that form a honeycomb structure. This structure results in a Pt (VI) and Pt (II) mixed-valence compound with both PtSe6 octahedra and PtSe4 square net coordination configurations. Temperature-dependent electrical transport measurements suggest two distinct anomalies: a resistivity crossover, mimic to the metal-insulator (M-I) transition at ~150 K, and a resistivity plateau at temperatures below 10 K. The resistivity crossover is not associated with any structural, magnetic, or charge order modulated phase transitions. Magnetoresistivity, Hall, and heat capacity measurements concurrently suggest an existing hidden state below 5 K in this system. Angle-resolved photoemission spectroscopy measurements reveal a metallic state and no dramatic reconstruction of the electronic structure up to 200 K. [ABSTRACT FROM AUTHOR]

Pressure-induced charge density wave (CDW) state can overcome the low-temperature limitation for practical application, thus seeking its traces in experiments is of great importance. Herein, we provide spectroscopic evidence for the emergence of room temperature CDW order in the narrow pressure range of 10–15 GPa in bulk VSe2. Moreover, we discovered an 8-coordination structure of VSe2 with C2/m symmetry in the pressure range of 35–65 GPa by combining the X-ray absorption spectroscopy, X-ray diffraction experiments, and the first-principles calculations. These findings are beneficial for furthering our understanding of the charge modulated structure and its behavior under high pressure. [ABSTRACT FROM AUTHOR]

[Display omitted] Antimony tin oxide (ATO)/lead selenide (PbSe) composite was rationally designed and fabricated on fluorine doped tin oxide glass (FTO) for using as counter electrode (CE) of quantum dot sensitized solar cells (QDSSCs). The electrocatalytic activity of the CE is deeply investigated in the polysulfide electrolyte by employing the Tafel, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) of the symmetrical cells. The results confirm that the ATO/PbSe CE has better electrocatalytic activity and stability than that of PbSe CE obtained by pulse voltage electrodeposition (PVD). The enhanced electrocatalytic performance of ATO/PbSe CE can be attributed to its high specific surface area, excellent permeability, conductivity and interface connectivity, which provide more electrocatalytic active sites for the reduction of polysulfide species, as well as fast channels for ions diffusion and electron transport. As a result, the CdS QDSSCs and CdS/CdSe co-sensitized QDSSCs assembled by the ATO/PbSe CE exhibits better power conversion efficiency (η) of 1.72% and 5.59%, respectively than that of PbSe CE obtained by PVD. Furthermore, photovoltaic property of the ATO/PbSe CE in CdS/CdSe co-sensitized QDSSCs keeps stable for over 200 min. This present work provides a simple and effective strategy for the construction of high-performance CE materials of QDSSCs. [ABSTRACT FROM AUTHOR]

[Display omitted] An innovative electrochemical nanocomposite for the detection of guanosine (Gua) was proposed by in situ encapsulation of nickel–iron bimetallic selenides confined into honeycomb-like nitrogen doped porous carbon nanosheets, denoted as (Ni,Fe)Se 2 / N -PCNs. The porous carbon nanosheets were prepared by utilizing nickel–iron layered double hydroxide (Ni-Fe LDH) as the substrate and zeolitic imidazolate frameworks (ZIF-67) nanocrystals as the sacrificial templates via hydrothermal synthesis, followed by a process of acid etching and pyrolysis selenylation. Interestingly, the nickel-ferric bimetallic selenides material (Ni,Fe)Se 2 , is rarely fabricated successfully using selenylation treatment, which is a highly conductive and robust support to promote the electron transport. Meanwhile, the obtained (Ni,Fe)Se 2 / N -PCNs have the favorable architectural features of both unique three-dimensional (3D) porous structural and hierarchical connectivity, which are expected to provide more active sites for electrochemical reactions and ease of electron, ion, and biomolecule penetration. Benefiting from the inherent virtues of its composition, together with unique structural advantages, the (Ni,Fe)Se 2 / N -PCNs possess ideal sensing properties for guanosine detection with a low detection limit of 1.20 × 10-8 M, a wide linear range of 5.30 × 10-8 ~ 2.27 × 10-4 M and a good stability. Superb selectivity for potential interfering species and superb recoveries in serum suggests its feasibility for practical applications. [ABSTRACT FROM AUTHOR]

Flexible photodetectors have attracted great attention in fields such as display screens, aerospace, and civil engineering due to their wearable and large-area foldable advantages. Therefore, the hybrid structure of Bismuth oxyselenide(Bi 2 O 2 Se)/Graphene was successfully synthesized in this work through mechanical compound method. In addition, we constructed a photodetector based on solid-state electrolyte, which has the advantage of small size, light weight, and portability. Photoelectrochemical tests show that the Bi 2 O 2 Se/graphene photodetector based on solid-state electrolyte has excellent photoresponse characteristics under 0 V, and its photocurrent density is 400 nA/cm2 when the optical power is 120 mW/cm2. In addition, the Bi 2 O 2 Se/graphene photodetector exhibits superb flexibility. After different bending angles and bending times, the photocurrent slightly decreases, which may be due to small cracks in the bending process. Finally, the tested Bi 2 O 2 Se/graphene solid-state photodetector showed excellent stability. The photocurrent was only slightly reduced after 1000 s, which was 81% of the original value. The result shows that the hybrid structure of Bi 2 O 2 Se/Graphene has potential in the field of photodetectors with exceptional performance, excellent stability and mechanical properties. [ABSTRACT FROM AUTHOR]

Pressure-induced charge density wave (CDW) state can overcome the low-temperature limitation for practical application, thus seeking its traces in experiments is of great importance. Herein, we provide spectroscopic evidence for the emergence of room temperature CDW order in the narrow pressure range of 10–15 GPa in bulk VSe2. Moreover, we discovered an 8-coordination structure of VSe2 with C2/m symmetry in the pressure range of 35–65 GPa by combining the X-ray absorption spectroscopy, X-ray diffraction experiments, and the first-principles calculations. These findings are beneficial for furthering our understanding of the charge modulated structure and its behavior under high pressure. [ABSTRACT FROM AUTHOR]

We report a layered ternary selenide BaPt4Se6 featuring sesqui-selenide Pt2Se3 layers sandwiched by Ba atoms. The Pt2Se3 layers in this compound can be derived from the Dirac-semimetal PtSe2 phase with Se vacancies that form a honeycomb structure. This structure results in a Pt (VI) and Pt (II) mixed-valence compound with both PtSe6 octahedra and PtSe4 square net coordination configurations. Temperature-dependent electrical transport measurements suggest two distinct anomalies: a resistivity crossover, mimic to the metal-insulator (M-I) transition at ~150 K, and a resistivity plateau at temperatures below 10 K. The resistivity crossover is not associated with any structural, magnetic, or charge order modulated phase transitions. Magnetoresistivity, Hall, and heat capacity measurements concurrently suggest an existing hidden state below 5 K in this system. Angle-resolved photoemission spectroscopy measurements reveal a metallic state and no dramatic reconstruction of the electronic structure up to 200 K. [ABSTRACT FROM AUTHOR]