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Silver indium selenide (AgInSe2) has been proposed as an efficient absorber material for sustainable solar cells. Phase pure preparation of this exotic material in the nano regime is highly desirable. This report describes the design and synthesis of a new heterobimetallic complex [(Ph3P)2Ag(μ-SeCH2Ph)2In(SeCH2Ph)2] along with its structural characterization. This complex acts as an air enduring, normal temperature and pressure (NTP) stable versatile single source precursor for synthesizing bulk, nanocrystalline and thin film of AgInSe2. The crystal structure, phase purity, morphology, elemental composition and band gap of the synthesized materials were determined from powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and diffuse reflectance spectroscopy (DRS-UV), respectively. The band gap of the nanocrystalline AgInSe2 lies in the range suitable for solar cell applications. A prototype photoelectrochemical cell fabricated with the pristine AgInSe2 nanoparticles exhibits high photoresponsivity, which makes them a suitable candidate for clean energy applications. [ABSTRACT FROM AUTHOR]

Bismuthinite (Bi2S3) nanostructures have garnered significant interest due to their appealing photoresponsivity which has positioned them as an attractive choice for energy conversion applications. However, to utilize their full potential, a simple and economically viable method of preparation is highly desirable. Herein, we present the synthesis and characterization including structural elucidation of a new air- and moisture-stable bismuth-pyrimidylthiolate complex. This complex serves as an efficient single-source molecular precursor for the facile preparation of phase-pure Bi2S3 nanostructures. Powder X-ray diffraction (PXRD), Raman spectroscopy, electron dispersive spectroscopy (EDS) and electron microscopy techniques were used to assess the crystal structure, phase purity, elemental composition and morphology of the as-prepared nanostructures. This study also revealed the profound effects of temperature and growth duration on the crystallinity, phase formation and morphology of nanostructures. The optical band gap of the nanostructures was tuned within the range of 1.9–2.3 eV, which is blue shifted with respect to the bulk bandgap and suitable for photovoltaic applications. Liquid junction photo-electrochemical cells fabricated from the as-prepared Bi2S3 nanostructure exhibit efficient photoresponsivity and good photo-stability, which project them as promising candidates for alternative low-cost photon absorber materials. [ABSTRACT FROM AUTHOR]

Copper selenide nanostructures have attracted growing attention due to their potential application in cost effective and sustainable solar cells and photocatalysis. This study describes the facile conversion of a new one dimensional copper(II) coordination polymer constructed from 4,4′-dipyridyldiselenide (1D-CupySe) into copper selenide nanostructures. The structure of 1D-CupySe elucidated from single crystal XRD revealed the formation of a one-dimensional zig-zag chain of the [{Cu2(μ(O,O′)-OAc)4}(μ(N,N′)-4,4′-py2Se2)] repeating unit. Interestingly, the diselenide linkage remains intact in the polymer which can be readily cleaved under mild thermolytic conditions, thereby facilitating intra-molecular selenium transfer to the Cu(II) center. The solvent assisted breakdown of 1D-CupySe revealed the formation of Cu2−xSe nanostructures. Importantly, different compositions of Cu2−xSe (Cu1.75Se and Cu2Se) could be isolated by the choice of solvent. The as-prepared nanostructures have been thoroughly characterized by pXRD, EDS, electron microscopy and DRS for assessing their phase purity, crystal structure, elemental composition, morphology and optical properties. The nanostructures exhibit a narrow band gap in the range of 2.3–2.45 eV. Prototype photoelectrochemical cells fabricated using the nanostructures exhibit high current generation which makes them suitable alternatives for non-toxic and low-cost photon absorber materials. [ABSTRACT FROM AUTHOR]

Copper and copper oxide nanostructures are ubiquitous in materials science owing to their high potential in energy and environment applications. This article describes the utility of a 2D Cu(II) coordination polymer (2D-CuPDC) derived from 2,5-pyridinedicarboxylic acid linker, as a precursor for selective isolation of Cu and CuO nanostructures. The structure of the coordination polymer has been elucidated from single crystal XRD. The Cu center in 2D-CuPDC is in a distorted square pyramidal geometry with the polymeric unit propagating along the ac-plane when viewed along the a-axis. The thermogravimetric analysis of 2D-CuPDC indicates that it can be an efficient molecular precursor for copper oxide nanoparticles. The solvent assisted and solvent free breakdown of the 2D-CuPDC network revealed the formation of Cu nano-flowers and porous CuO nanostructures, respectively. The crystal structure, phase purity, morphology, elemental composition and band gap of these nanostructures were evaluated from pXRD, electron microscopy, EDS and DRS-UV, respectively. The band gap of these nanostructures lies in the range suitable for photocatalytic applications. This coordination polymer driven synthesis of Cu and CuO nanostructures can be expanded for other technologically important metal and metal oxide nanostructures. [ABSTRACT FROM AUTHOR]

Indium selenides (InSe and In2Se3) have earned a special place among the 2D layered metal chalcogenides owing to their nontoxic nature and favourable carrier mobility. Additionally, they are also being projected as next generation battery anodes with high theoretical lithium-ion storage capacities. While the development of indium selenide-based batteries is still in its embryonic stage, a simple and easily scalable synthetic pathway to access these materials is highly desirable for energy storage applications. This study reports a controlled synthetic route to nanometric cubic InSe and hexagonal In2Se3 materials through proper choice of coordinating solvents from a structurally characterized air and moisture stable single source molecular precursor: tris(4,6-dimethyl-2-pyrimidylselenolato)indium(III). The crystal structure, phase purity, composition, morphology and band gap of the nanomaterials were thoroughly evaluated by pXRD, energy dispersive X-ray spectroscopy (EDS), electron microscopy (SEM and TEM), and diffuse reflectance spectroscopy (DRS), respectively. The pristine InSe and In2Se3 nanostructures have been employed as anode materials in lithium-ion batteries (LIBs). Both the cells deliver reasonably high initial discharge capacities with a cyclability of 200 and 620 cycles for cubic InSe and hexagonal In2Se3 respectively with ∼100% coulombic efficiency. [ABSTRACT FROM AUTHOR]

Copper sulfides have gained significant attention as alternative electrodes for rechargeable batteries. A simple and easily scalable synthetic pathway to access these materials is highly desirable. This paper describes the facile synthesis of metal-rich digenite Cu1.8S nanocrystals from a structurally characterized new single-source molecular precursor in various high boiling solvents of varied polarity. The as-prepared nanostructures were thoroughly characterized by PXRD, Raman spectroscopy, EDS, XPS, electron microscopy techniques and diffuse reflectance spectroscopy to understand the crystal structure, phase purity, elemental composition, morphology and band gap. It was found that the reaction solvent has a profound role on their crystallite size, morphology and band gap, however the crystal structure and phase purity remained unaffected. Pristine Cu1.8S nanostructures have been employed as an anode material in lithium-ion batteries (LIBs). The cell delivers a high initial charge capacity of ∼462 mA h g−1 and retains a capacity of 240 mA h g−1 even after 300 cycles at 0.1 A g−1. DFT calculations revealed that multi-size polyhedron layers in the direction perpendicular to the two Li movement channels aid in the sustainable uptake of Li atoms with controlled volume expansion. The structure-mediated flexibility of the metal-rich Cu1.8S lattice during lithiation permits high cyclability with reasonable retention of capacity. [ABSTRACT FROM AUTHOR]

Copper germanium sulfides (CGSs), a class of ternary I–IV–VI semiconductor metal chalcogenides, are considered quite desirable when it comes to efficient light harvesting materials for cost-effective and sustainable solar cells. Producing phase-pure CGS materials, free from binary impurities at the nanoscale is highly desirable. This report outlines a simple and easily scalable pathway toward phase-pure cubic Cu2GeS3 nanostructures via the thermolysis of copper and germanium isopropylxanthates in oleylamine (OAm). The crystal structure, phase purity, morphology, elemental composition and band gap of the as-synthesized Cu2GeS3 nanostructures were thoroughly evaluated via powder X-ray diffraction (PXRD), Raman spectroscopy, scanning and transmission electron microscopy (SEM and TEM), energy dispersive X-ray spectroscopy (EDS), and UV-Vis and diffuse reflectance spectroscopy (DRS), respectively. The band gap of these nanomaterials lies in an optimum range for solar cell applications. Finally, the pristine Cu2GeS3 nanocrystal-based prototype photoelectrochemical cells exhibit photovoltaic activity along with high photoresponsivity and stability under alternating light and dark conditions, which make them promising candidates for alternative low-cost photon absorber materials. [ABSTRACT FROM AUTHOR]

A paucity of red emitting phosphors efficiently excitable in the soft UV region has been a huge barrier in solid state lighting applications from the combination of a near-UV LED exciting chip and down conversion phosphors. The present work unveils the competence of an Eu-doped yttrium pyrogermanate phosphor (Y2Ge2O7:Eu) efficiently excitable in the soft-UV region. Single phase Y2Ge2O7:Eu with 2–10% Eu content was prepared by conventional solid-state reaction and thoroughly characterized using XRD, FTIR, RAMAN and XPS techniques. To examine the potential of the Y2Ge2O7:Eu phosphor, its photoluminescence behavior was compared with standard commercial red phosphor Y2O3:Eu. Remarkably, the results reveal that Y2Ge2O7:Eu retains the pros of the commercial phosphor and compensates for its cons. Whilst the emission profile, decay lifetime and internal quantum efficiency of Y2Ge2O7:Eu are almost identical to those of Y2O3:Eu, its Eu-incorporation capacity without concentration quenching is as high as 10% contrary to 5–6% of Y2O3:Eu owing to the less dense distribution of Y-sites in the Y2Ge2O7 host. High loading of Eu-content makes Y2Ge2O7:Eu suitable for high contrast displays. Whereas the Y2O3:Eu phosphor has negligible absorption efficiency in the soft UV region, the Y2Ge2O7:Eu phosphor has its maximum absorption efficiency around 390 nm nicely aligned with the emission of near UV LED chips. DFT calculations revealed that relatively deeper positioning of the Y2Ge2O7 valence electron energy states and associated covalency are decisive for its demonstration of competing performance. Successful dispersion of Y2Ge2O7:Eu inside a polymer matrix further endorses its potential towards future flexible device applications. [ABSTRACT FROM AUTHOR]

Copper selenide (Cu1.8Se) and silver selenide (Ag2Se) have garnered unprecedented attention as efficient absorber materials for cost-effective and sustainable solar cells. Phase pure preparation of these exotic materials in a nano-regime is highly desirable. This account outlines a simple and easily scalable pathway to Cu1.8Se and Ag2Se nanocrystals using novel complexes [Cu{2-SeC5H2(Me-4,6)2N}]4 (1), [Ag{2-SeC5H2(Me-4,6)2N}]6 (2) and [Ag{2-SeC5H3(Me-5)N}]6·2C6H5CH3 (3·2C6H5CH3) as single source molecular precursors (SSPs). Structural studies revealed that the Cu and Ag complexes crystallize into tetrameric and hexameric forms, respectively. This observed structural diversity in the complexes has been rationalized via DFT calculations and attributed to metal–metal bond endorsed energetics. The thermolysis at relatively lower temperature in oleylamine of complex 1 afforded cubic berzelianite Cu1.8Se and complexes 2 and 3 produced orthorhombic naumannite Ag2Se nanocrystals. The low temperature synthesis of these nanocrystals seems to be driven by the observed preformed Cu4Se4 and Ag6Se6 core in the complexes which have close resemblance with the bulk structure of the final materials (Cu1.8Se and Ag2Se). The crystal structure, phase purity, morphology, elemental composition and band gap of these nanocrystals were determined from pXRD, electron microscopy (SEM and TEM), EDS and DRS-UV, respectively. The band gap of these nanocrystals lies in the range suitable for solar cell applications. Finally, these nanocrystal-based prototype photo-electrochemical cells exhibit high photoresponsivity and stability under alternating light and dark conditions. [ABSTRACT FROM AUTHOR]

Stibnite Sb2S3 and tetrahedrite Cu12Sb4S13 nanostructures being economical, environmentally benign and having a high absorption coefficient are highly promising materials for energy conversion applications. However, producing these materials especially tetrahedrite in the phase pure form is a challenging task. In this report we present a structurally characterized single source molecular precursor [Sb(4,6-Me2pymS)3] for the facile synthesis of binary Sb2S3 as well as ternary Cu12Sb4S13 in oleylamine (OAm) at a relatively lower temperature. The as-prepared Sb2S3 and Cu12Sb4S13 nanostructures were thoroughly checked for their phase purity, elemental composition and morphology by powder X-ray diffraction (pXRD), electron dispersive spectroscopy (EDS) and electron microscopy techniques. pXRD and EDS studies confirm the formation of phase pure, crystalline orthorhombic Sb2S3 and cubic Cu12Sb4S13. The SEM, TEM and HRTEM images depict the formation of well-defined nanorods and nearly spherical nanocrystals for Sb2S3 and Cu12Sb4S13, respectively. The Sb2S3 nanorods and Cu12Sb4S13 nanocrystals exhibit an optical bandgap of ∼1.88 and 2.07 eV, respectively, which are slightly blue-shifted relative to their bulk bandgap, indicating the quantum confinement effect. Finally, efficient photoresponsivity and good photo-stability were achieved in the as-prepared Sb2S3 and Cu12Sb4S13 nanostructure-based prototype photo-electrochemical cell, which make them promising candidates for alternative low-cost photon absorber materials. [ABSTRACT FROM AUTHOR]

Due to the ongoing industrial revolution, solar-driven water splitting and pesticide degradation are highly sought to cope with catastrophes such as depleting fossil reservoirs, global warming, and environmental degradation. The development of stable and efficient photocatalysts has been extensively attempted for past several decades. Herein, SnO2-based nanomaterials (NMs) have been extensively explored due to their higher stability and wide band gap semiconducting properties. Thus, this review summarizes the recent innovations made on SnO2-based NMs/electrodes/scaffolds for highly efficient photocatalytic water splitting and pesticide degradation based on the type of dopants, their nature, concentration, sensitizers, chemical additives, scavengers, etc., with the corresponding mechanistic aspects. The theoretical aspects of SnO2-based NMs have also been elaborated. Various trend-setting modifications such as band gap engineering, enhanced charge separation, and electron transfer with various SnO2-based NMs are discussed in light of the search for real-life photocatalysts. [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]