Substrate-induced strain in molybdenum disulfide grown by aerosol-assisted chemical vapor deposition.

Transition metal dichalcogenides have been extensively studied in recent years because of their fascinating optical, electrical, and catalytic properties. However, low-cost, scalable production remains a challenge. Aerosol-assisted chemical vapor deposition (AACVD) provides a new method for scalable thin film growth. In this study, we demonstrate the growth of molybdenum disulfide (MoS2) thin films using AACVD method. This method proves its suitability for low-temperature growth of MoS2thin films on various substrates, such as glass, silicon dioxide, quartz, silicon, hexagonal boron nitride, and highly ordered pyrolytic graphite. The as-grown MoS2shows evidence of substrate-induced strain. The type of strain and the morphology of the as-grown MoS2highly depend on the growth substrate's surface roughness, crystallinity, and chemical reactivity. Moreover, the as-grown MoS2shows the presence of both direct and indirect band gaps, suitable for exploitation in future electronics and optoelectronics.

Juggling Optoelectronics and Catalysis: The Dual Talents of Bench Stable 1,4-Azaborinines.

Boron- and nitrogen-doped polycyclic aromatic hydrocarbons (B-PAHs) have established a strong foothold in the realm of organic electronics. However, their catalytic potential remains largely untapped. In this study, we synthesise and characterise two bench stable B,N-doped PAH derivatives based on a 1,4-azaborinine motif. Most importantly, the anthracene derived structure is an efficient catalyst in the reduction of various carbonyls and imines. These results underscore the potential of B,N-PAHs in catalytic transformations, setting the stage for deeper exploration in this chemical space.

Reeling them in: Ph2PSiMe3 in the sequential formation of InP magic-sized clusters.

Indium phosphide magic-sized clusters (MSCs) have been identified as a key step in the growth of InP quantum dots (QDs). However, the need for elevated temperatures to form QDs from MSCs has limited our understanding of this transformation. Herein, we utilize Ph2PSiMe3 to identify additional MSC intermediate species, which absorb from 365 nm to 490 nm. Excitingly, particle growth was carried out at 100 °C without the use of acidic surfactants. We show that despite being discrete, stable, and isolable sizes of MSCs, they form a reaction continuum, thus providing further insight into the growth mechanism of InP.

Correction: Synthesis of Ca(PF6)2, formed via nitrosonium oxidation of calcium.

Correction for 'Synthesis of Ca(PF6)2, formed via nitrosonium oxidation of calcium' by Evan N. Keyzer et al., Chem. Commun., 2017, 53, 4573-4576.

Energy transfer and photoluminescence properties of lanthanide-containing polyoxotitanate cages coordinated by salicylate ligands.

Polyoxotitanate (POT) cages have attracted considerable attention recently; much of this from the fact that they can be considered to be structural models for the technologically important semiconductor TiO2. Among the reported POT cages, lanthanide-containing (Ln-POT) cages are of particular interest owing to the fascinating luminescence properties of Ln3+ ions and the versatile coordination environments that they can adopt. In the present study, we report the energy transfer mechanism and photoluminescence properties of a series of isostructural Ln-POT cages coordinated by salicylate ligands, of general formula [LnTi6O3(OiPr)9(salicylate)6] (Ln-1, Ln = La to Er excluding Pm). Both visible (for Pr-1, Sm-1, Eu-1, Ho-1 and Er-1) and near-infrared (for Nd-1 and Er-1) Ln3+-centred photoluminescence can be sensitised in solution, and most importantly, their excitation bands all extend well into the visible region up to 475 nm. With the assistance of steady-state and time-resolved photoluminescence spectroscopy, an energy-transfer mechanism involving the salicylate-to-Ti4+ charge-transfer state is proposed to account for the largely red-shifted excitation wavelengths of these Ln-1 cages. The photoluminescence quantum yield of Nd-1 upon excitation via the charge-transfer state reaches 0.30 ± 0.01% in solution, making it among the highest reported values for Nd3+-complexes in the literature.

Black phosphorus with near-superhydrophobic properties and long-term stability in aqueous media.

Black phosphorus is a two-dimensional material that has potential applications in energy storage, high frequency electronics and sensing, yet it suffers from instability in oxygenated and/or aqueous systems. Here we present the use of a polymeric stabilizer which prevents the degradation of nearly 68% of the material in aqueous media over the course of ca. 1 month.

On the phase control of CuInS2 nanoparticles from Cu-/In-xanthates.

In this paper we report the synthesis and single-crystal X-ray characterisation of six novel indium(iii) xanthate complexes. These xanthates have been used as an In-source for the synthesis of highly crystalline CuInS2 nanoparticles in conjunction with a Cu(i)-xanthate. In synthesising the nanoparticles we have also demonstrated an ability to control the phase of the material through choice of solvent.

A simple route to complex materials: the synthesis of alkaline earth - transition metal sulfides.

A simple, low-temperature synthesis of a family of alkaline earth metal chalcogenide thin films is reported. These materials have previously only been produced from demanding, high temperature, high pressure reactions. The decomposition of calcium, barium and copper xanthates leads to the clean formation of CaS, BaS, CaCu2S2, ß-BaCu2S2 and ß-BaCu4S3.

Novel Xanthate Complexes for the Size-Controlled Synthesis of Copper Sulfide Nanorods.

We present a simple, easily scalable route to monodisperse copper sulfide nanocrystals by the hot injection of a series of novel copper(I) xanthate single-source precursors [(PPh3)2Cu(S2COR)] (R = isobutyl, 2-methoxyethyl, 2-ethoxyethyl, 1-methoxy-2-propyl, 3-methoxy-1-butyl, and 3-methoxy-3-methyl-1-butyl), whose crystal structures are also reported. We show that the width of the obtained rods is dependent on the length of the xanthate chain, which we rationalize through a computational study, where we show that there is a relationship between the ground-state energy of the precursor and the copper sulfide rod width.

Shining a light on transition metal chalcogenides for sustainable photovoltaics.

Transition metal chalcogenides are an important family of materials that have received significant interest in recent years as they have the potential for diverse applications ranging from use in electronics to industrial lubricants. One of their most exciting properties is the ability to generate electricity from incident light. In this perspective we will summarise and highlight the key results and challenges in this area and explain how transition metal chalcogenides are a good choice for future sustainable photovoltaics.

A Modular Approach to Inorganic Phosphazane Macrocycles.

Inorganic macrocycles, based on non-carbon backbones, present exciting synthetic challenges in the systematic assembly of inorganic molecules, as well as new avenues in host-guest and supramolecular chemistry. Here we demonstrate a new high-yielding modular approach to a broad range of trimeric and hexameric S- and Se-bridged inorganic macrocycles based on cyclophosphazane frameworks, using the building blocks [S=(H)P(µ-NR)]2 . The method involves the in situ generation of the key intermediate [E....._ (S....._ )P(µ-NR)]22- (E=S, Se) dianion, which can be reacted with electrophilic [ClP(µ-NR)]2 to give PIII /PV hexameric rings or reacted with I2 to give trimeric PV variants. Important issues which are highlighted in this work are the competitive bridging ability of S versus Se in these systems and the synthesis of the first air-stable and chiral inorganic macrocycles.

Synthesis of Ca(PF6)2, formed via nitrosonium oxidation of calcium.

The development of rechargeable Ca-ion batteries as an alternative to Li systems has been limited by the availability of suitable electrolyte salts. We present the synthesis of complexes of Ca(PF6)2 (a key potential Ca battery electrolyte salt) via the treatment of Ca metal with NOPF6, and explore their conversion to species containing PO2F2- under the reaction conditions.

Synthesis, structure and paramagnetic NMR analysis of a series of lanthanide-containing [LnTi6O3(OiPr)9(salicylate)6] cages.

The influence of paramagnetic Ln3+ ions on the NMR behaviour is investigated via a series of new isostructural lanthanide-containing cages with the general formula [LnTi6O3(OiPr)9(salicylate)6] (Ln-1, Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho and Er). Compared to conventional coordination compounds containing Ln3+ ions, the peripheral ligands in Ln-1 are separated from the paramagnetic lanthanide centres by oxo-Ti4+ linkages, and therefore experience a weaker paramagnetic influence. As a result, all of the 1H and 13C NMR signals of these Ln-1 cages (except for Gd-1) are observed and can be unambiguously assigned, which provides an excellent platform for the in-depth study of the NMR behaviour of paramagnetic Ln3+ ions. Further analysis of the fully assigned paramagnetic signals suggests that the pseudo-contact component dominates the 1H NMR shifts, whereas both the pseudo-contact and Fermi-contact contributions affect the 13C shifts, although the majority of the resonance environments are at least four bonds distant from the central Ln3+ ion. Our results also show that the use of Bleaney's factors to describe the pseudo-contact shift is inadequate for this Ln-1 cage series.

The synthesis and characterization of Cu2ZnSnS4 thin films from melt reactions using xanthate precursors.

Kesterite, Cu2ZnSnS4 (CZTS), is a promising absorber layer for use in photovoltaic cells. We report the use of copper, zinc and tin xanthates in melt reactions to produce Cu2ZnSnS4 (CZTS) thin films. The phase of the as-produced CZTS is dependent on decomposition temperature. X-ray diffraction patterns and Raman spectra show that films annealed between 375 and 475 °C are tetragonal, while at temperatures <375 °C hexagonal material was obtained. The electrical parameters of the CZTS films have also been determined. The conduction of all films was p-type, while the other parameters differ for the hexagonal and tetragonal materials: resistivity (27.1 vs 1.23 Ω cm), carrier concentration (2.65 × 10+15 vs 4.55 × 10+17 cm-3) and mobility (87.1 vs 11.1 cm2 V-1 s-1). The Hall coefficients were 2.36 × 103 versus 13.7 cm3 C-1.

The influence of halides in polyoxotitanate cages; dipole moment, splitting and expansion of d-orbitals and electron-electron repulsion.

Metal-doped polyoxotitanate (M-POT) cages have been shown to be efficient single-source precursors to metal-doped titania [TiO2(M)] (state-of-the-art photocatalytic materials) as well as molecular models for the behaviour of dopant metal ions in bulk titania. Here we report the influence halide ions have on the optical and electronic properties of a series of halide-only, and cobalt halide-'doped' POT cages. In this combined experimental and computational study we show that halide ions can have several effects on the band gaps of halide-containing POT cages, influencing the dipole moment (hole-electron separation) and the structure of the valance band edge. Overall, the band gap behaviour stems from the effects of increasing orbital energy moving from F to I down Group 17, as well as crystal-field splitting of the d-orbitals, the potential effects of the Nephelauxetic influence of the halides and electron-electron repulsion.

Synthetic routes to iron chalcogenide nanoparticles and thin films.

Iron chalcogenides are earth abundant, cheap and environmentally benign materials that have seen extensive research directed toward a range of applications, most notably for photovoltaics. The most common forms of materials for these applications are either nanoparticles or thin films. This perspective seeks to summarise the key synthetic routes to these materials by highlighting the key aspects that lead to control over phase and morphology.

Novel properties and potential applications of functional ligand-modified polyoxotitanate cages.

Functional ligand-modified polyoxotitanate (L-POT) cages of the general type [TixOy(OR)z(L)m] (OR = alkoxide, L = functional ligand) can be regarded as molecular fragments of surface-sensitized solid-state TiO2, and are of value as models for studying the interfacial charge and energy transfer between the bound functional ligands and a bulk semiconductor surface. These L-POTs have also had a marked impact in many other research fields, such as single-source precursors for TiO2 deposition, inorganic-organic hybrid material construction, photocatalysis, photoluminescence, asymmetric catalysis and gas adsorption. Their atomically well-defined structures provide the basis for the understanding of structure/property relationships and ultimately for the rational design of new cages targeting specific uses. This highlight focuses on recent advances in L-POTs research, with emphasis on their novel properties and potential applications.

How Does Substitutional Doping Affect Visible Light Absorption in a Series of Homodisperse Ti11 Polyoxotitanate Nanoparticles--A Comment on the Band Gap Determination of the Fe(II) Cages (Chem. Eur. J. 2015, 21, 11538).

There is no experimental support for the conclusion by Coppens and Chen in a recent paper that the (HOMO-LUMO) band gaps in a series of Fe(II) polyoxotitanate cages are in the range 1.43-1.59 eV.

Synthesis, structure and properties of the manganese-doped polyoxotitanate cage [Ti18MnO30(OEt)20(MnPhen)3] (Phen = 1,10-phenanthroline).

The novel heterometallic polyoxotitanate cage [Ti18MnO30(OEt)20(MnPhen)3] (1), obtained by solvothermal reaction of Ti(OEt)4 with Mn(AcO)3·(H2O)2 and 1,10-phenanthroline (Phen) in EtOH, has a C3 symmetric core structure containing an interstitial tetrahedral Mn(II) ion and is surrounded by three Mn(II)(Phen) fragments. The molecular structure is retained in thin film electrodes of 1 deposited by solution drop-casting onto fluorinated tin oxide (FTO). Both solid state and solution phase electrochemical measurements show dual redox couples, consistent with the two distinct Mn coordination environments in the cage structure. Sintering of 1 in air at 600 °C produces a black crystalline solid which consists of Mn-doped TiO2 (mainly in the rutile phase) together with α-Mn2O3. Such a composite semiconductor has an optical band gap of ca. 1.80 eV, similar to that of α-Mn2O3.

Theory and practice: bulk synthesis of C3B and its H2- and Li-storage capacity.

Previous theoretical studies of C3B have suggested that boron-doped graphite is a promising H2- and Li-storage material, with large maximum capacities. These characteristics could lead to exciting applications as a lightweight H2-storage material for automotive engines and as an anode in a new generation of batteries. However, for these applications to be realized a synthetic route to bulk C3B must be developed. Here we show the thermolysis of a single-source precursor (1,3-(BBr2)2C6H4) to produce graphitic C3B, thus allowing the characteristics of this elusive material to be tested for the first time. C3B was found to be compositionally uniform but turbostratically disordered. Contrary to theoretical expectations, the H2- and Li-storage capacities are lower than anticipated, results that can partially be explained by the disordered nature of the material. This work suggests that to model the properties of graphitic materials more realistically, the possibility of disorder must be considered.