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Metakaolin-based geopolymers (MKGP) were optimised by varying the operating conditions using the central composite design (CCD) and the response surface method (RSM) to optimise the operating variables affecting MKGP formation and their adsorption efficiency. The MKGP was characterised and tested for the removal of methylene blue (MB) from an aqueous environment. Results show that the MKGP5 with the most organised structure exhibits the highest MB removal efficiency. Parameters like the adsorbent dose, the pH, the contact time, the initial dye concentration, and the temperature were optimised to improve the adsorption efficiency of MB. The results also demonstrated the accuracy and feasibility of CCD simulation to develop a well-converted geopolymer adsorbent for water treatment. [ABSTRACT FROM AUTHOR]

Single crystals of strontium tetra­cobalt tris­(orthophosphate) hydroxide, SrCo4(OH)(PO4)3, were grown serendipitously under hydro­thermal conditions at 473 K. The crystal structure consists of undulating chains of edge-sharing [CoO6] octa­hedra that are linked into (010) layers by common vertices between chains. Adjacent layers are linked along [010] into a framework structure by tetra­hedral [CoO4] units and by PO4 tetra­hedra. The framework delimits channels extending along [100] in which the eleven-coordinate strontium cations are situated. Bifurcated O—H···O hydrogen bonds of weak strengths consolidate the crystal packing. The title compound was also characterized by infrared spectroscopy. [ABSTRACT FROM AUTHOR]

Quaternary compound Cu2CoSnS4 (CCTS) is a potential candidate absorber layer in thin film solar cells to produce clean and inexhaustible energy. In this work the Cu2CoSnS4 (CCTS) thin film was synthesized for the first time by co-electrodeposition of Cu–Co–Sn–S precursors on Molybdenum substrate, followed by a high temperature (500 °C) sulfurization under Argon atmosphere. The potential deposition (−0.95 V/SCE) was determined from cyclic voltammetry. The structure, composition and morphology of the CCTS thin film is characterized in detail by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and energy dispersion spectroscopy. The p-type conductivity of CCTS thin film was confirmed using Mott–Schottky analysis and the band gap value was evaluated to be 1.56 eV, which makes CCTS a promising material for solar cell applications. [ABSTRACT FROM AUTHOR]

CZTS thin films are deposited onto glass and Mo-coated glass substrates by ultrasonic spray technique, followed by a sulfurization under argon atmosphere at 500 °C during 1 h. We have investigated how the addition of the alkali can influence Cu2ZnSnS4 thin films properties. X-ray diffraction and Raman spectroscopy proved that CZTS has the kesterite structure with a preferential orientation along 112. The values of Cu/(Zn+Sn) and (Zn/Sn) ratios, determined by energy dispersive spectroscopy, for undoped CZTS and alkali-doped CZTS are observed to be affected by the alkali doping. The electrical resistivity, for CZTS films deposited on glass substrates, decreased after alkali doping from 9.2 10−1 Ω · cm for undoped CZTS to reach 1.8 10−1 and 4.2 10−1 Ω · cm for 15% content of Na and K, respectively. [ABSTRACT FROM AUTHOR]

Kesterite Cu2ZnSnS4 (CZTS) is a very promising absorber material for low cost and high efficiency thin film photovoltaic cells due to its direct band gap and to its high absorption coefficient. In this work, CZTS layers were deposited onto Mo-coated glass substrates using a single step electrodeposition process. Sulfurization treatment was performed under Argon atmosphere at 500°C. The effect of the deposition time in the range of 10 min-40 min was investigated. X-ray diffraction and Raman spectroscopy have confirmed the Kesterite structure of all deposited films. The surface morphology of the samples was examined using scanning electron microscopy. Cu/(Zn+Sn) of about 0.80, determined by energy dispersive X-ray spectroscopy, was reached for CZTS films electrodeposited during 30 min. Photoluminescence Spectroscopy showed a broad PL band centered around 1.45 eV. [ABSTRACT FROM AUTHOR]

Delafossite materials are considered to be a promising range of transparent conductive oxides for optoelectronic applications. The complications that have held back their implementation in practical devices lie in the complex growth methods that are required and in the formation of undesirable secondary phases. Herein, a fast, simple, and low-cost deposition method allowing the deposition of high-quality 2H-CuFeO 2 nanostructured thin films is employed. The effect of Sr doping on the properties of spray-coated CuFeO 2 thin film annealed at 850 °C is reported. X-ray diffraction (XRD) analysis revealed the delafossite structures of all the samples corresponding to the 2H-CuFeO 2 phase. The lattice spacing decreased with increasing substitution of Sr at the Cu site. Raman analysis further authenticated the structural results collected via XRD analysis. Surface scanning using field-emission scanning electron microscopy revealed the formation of nanostructured CuFeO 2 thin film possessing high crystalline quality, with the nanocrystal size increasing as the dopant content was increased. Energy-dispersive X-ray analysis allowed the quantification of the elements content via determining the ratios of the main elements as well as the dopant content in each sample. The optical properties of the samples showed strong light absorption in the visible region with a decrease in the band gap values with Sr insertion. First-principles calculations using density functional theory (DFT) were conducted to strengthen the experimental findings regarding the nature of the bonds in the hexagonal lattice of the CuFeO 2 compound and the effect of Sr doping on its characteristics. The electrical properties measured at room temperature revealed p-type conductivity with tunable resistivity, while the samples displayed increased electron mobility as a function of the dopant content. Consequently, our work introduced an efficient and cost-effective synthesis route for the preparation of high-quality nanostructured 2H-CuFeO 2 thin films, paving the way to facilitate further device applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Single crystals of strontium tetra-cobalt tris-(orthophosphate) hydroxide, SrCo 4 (OH)(PO 4 ) 3 , were grown serendipitously under hydro-thermal conditions at 473 K. The crystal structure consists of undulating chains of edge-sharing [CoO 6 ] octa-hedra that are linked into (010) layers by common vertices between chains. Adjacent layers are linked along [010] into a framework structure by tetra-hedral [CoO 4 ] units and by PO 4 tetra-hedra. The framework delimits channels extending along [100] in which the eleven-coordinate strontium cations are situated. Bifurcated O-H⋯O hydrogen bonds of weak strengths consolidate the crystal packing. The title compound was also characterized by infrared spectroscopy., (© Cherif et al. 2020.)