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Cobalt coordinated covalent organic frameworks have attracted increasing interest in the field of CO2 photoreduction to CO, owing to their high electron affinity and predesigned structures. However, achieving high conversion efficiency is challenging since most Co related coordination environments facilitate fast recombination of photogenerated electron-hole pairs. Here, we design two kinds of Co-COF catalysts with oxygen coordinated Co atoms and find that after tuning of coordination environment, the reported Co framework catalyst with Co-O4 sites exhibits a high CO production rate of 18000 µmol g−1 h−1 with selectivity as high as 95.7% under visible light irradiation. From in/ex-situ spectral characterizations and theoretical calculations, it is revealed that the predesigned Co-O4 sites significantly facilitate the carrier migration in framework matrixes and inhibit the recombination of photogenerated electron-hole pairs in the photocatalytic process. This work opens a way for the design of high-performance catalysts for CO2 photoreduction. A class of inexpensive aminoanthraquinone organic dyes are shown to facilitate visible-light-driven CO2 reduction. Overall reaction efficiencies were found to be optimal when both electron donating and accepting groups were on a single dye molecule. [ABSTRACT FROM AUTHOR]

Abstract: The dependences of the absorption spectra of chrome azurol S (CAS) and Al3+–CAS complexes on the concentration of ionic liquids (ILs), 1-alkyl-3-methylimidazolium bromide ([C n Mim]Br, with n =8, 10, 12), were measured at 298.15K in aqueous solutions with pH=5.6. It is found that ILs can induce the significant red-shifts of the wavelength at the absorption maximum (λ max) of Al3+–CAS complex from 545 to 646nm for [C8Mim]Br, and to 642nm for [C12Mim]Br and [C16Mim]Br, respectively. Accompanying the red-shifts, the absorbance at λ max, and thereby molar absorptivity (ɛ), changes markedly with the IL concentration, and consequently the effect of ILs on the absorbance at λ max is systematically investigated in this work. Along with the experimental results of resonance light scattering, the sensitization mechanism is analyzed from the aggregation of the ILs and the interactions of ILs with CAS and Al3+–CAS complexes. It is shown that the hydrophobic interactions of IL subaggregates with CAS in Al3+–CAS complex are the crucial factor for the sensitization. [Copyright &y& Elsevier]

Temperature dependence of the physiochemical characteristics of a room-temperature ionic liquid consisting of trimethylhexylammonium (TMHA) cation and bis(trifluoromethane) sulfonylimide (TFSI) anion containing different concentrations of LiTFSI salt was examined. Electrochemical properties of a spinel LiMn2O4 electrode in 1 M LiTFSI/TMHA-TFSI ionic electrolyte were investigated at different temperatures by using cyclic voltammetry, galvanostatic measurements, and electrochemical impedance spectroscopy. The Li/ionic electrolyte/LiMn2O4 cell exhibited satisfactory electrochemical properties with a discharge capacity of 108.2 mA h/g and 91.4% coulombic efficiency in the first cycle under room temperature. At decreased temperature, reversible capacity of the cell could not attain a satisfactory value due to the high internal resistance of the cell and the large activation energy for lithium ion transfer through the electrode/electrolyte interface. Anodic electrolyte oxidation results in the decrease of coulombic efficiency with increasing temperature. Irreversible structural conversion of the spinel LiMn2O4 in the ionic electrolyte, possibly associated with the formation of TMHA intercalated compounds and/or Jahn−Teller distortion, was considered to be responsible for the electrochemical decay with increasing cycles. [ABSTRACT FROM AUTHOR]

Biomineralization induced by microorganisms has become a hot spot in the field of carbonate sedimentology; however, the mechanisms involved still need to be explored. In this study, the bacterium Bacillus subtilis J2 (GenBank MG575432) was used to induce the precipitation of calcium carbonate minerals at Mg/Ca molar ratios of 0, 3, 6, 9, and 12. Bacillus subtilis J2 bacteria released ammonia to increase pH, but the ammonia released only made the pH increase to 8.25. Carbonic anhydrase was also produced to catalyze the hydration of carbon dioxide, and this process released carbonate and bicarbonate ions that not only increased pH but also elevated carbonate supersaturation. The biominerals formed at a Mg/Ca molar ratio of 0 were spherulitic, elongated, dumbbell-shaped, and irregularly rhombohedral calcite; at a Mg/Ca molar ratio of 3, the biominerals were calcite and aragonite, the weight ratio of calcite decreased from 26.7% to 15.6%, and that of aragonite increased from 73.3% to 84.4% with increasing incubation time. At higher Mg/Ca molar ratios, the biominerals were aragonite, and the crystallinity and thermal stability of aragonite decreased with increasing Mg/Ca molar ratios. FTIR results showed that many organic functional groups were present on/within the biominerals, such as C–O–C, N–H, C=O, O–H, and C–H. HRTEM-SAED examination of the ultra-thin slices of B. subtilis J2 bacteria showed that nano-sized minerals with poor crystal structure had grown or been adsorbed on the EPS coating. The EPS of the B. subtilis J2 strain contained abundant glutamic acid and aspartic acid, which could be deprotonated in an alkaline condition to adsorb Ca2+ and Mg2+ ions; this made EPS act as the nucleation sites. This study may provide some references for further understanding of the mechanism of biomineralization induced by microorganisms. [ABSTRACT FROM AUTHOR]

A two-dimensional (2D) nanoporous Ni(OH) 2 film was successfully developed from triethanolamine (TEA) as the alkali source and soft template using a scalable hydrothermal technique. The nanostructured Ni(OH) 2 film was flexible and translucent, and could be directly compressed on a current collector. Owing to the uniform well-defined morphology and stable structure, the Ni(OH) 2 film binder-free electrode displayed a high specific capacity, exceptional rate capability, and admirable cycle life. The specific capacitance was 453.6 mA h g -1 (1633 F g -1 ) at 0.5 A g -1 . The assembled Ni(OH) 2 //activated carbon (AC) asymmetric supercapacitor (ASC) device had an energy density of 58.7 W h kg -1 at a power density of 400 W kg -1 . These prominent electrochemical properties of Ni(OH) 2 were attributed to the high electrical conductivity, high surface area, and unique porous architecture. Free tailoring, binder-free, and direct pressing were the most significant achievements of the Ni(OH) 2 film in the development of high-performance energy storage devices., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

This study proposes a facile solvothermal synthesis of nickel tungstate (NiWO 4 ) nanowires for application as a novel cathode material for supercapacitors. The structure, morphology, surface area and pore distribution were characterized and their capacitive performances were investigated. The results showed that the NiWO 4 nanowires synthesized in ethylene glycol solvent could offer a high specific capacitance of 1190 F g -1 at a current density of 0.5 A g -1 and a capacitance retaining ratio of 61.5% within 0.5-10 A g -1 . When used as a cathodic electrode of an asymmetric supercapacitor (ASC), the NiWO 4 nanowire based device can be cycled reversibly in a high-voltage region of 0-1.7 V with a high specific capacitance of 160 F g -1 at 0.5 A g -1 , which therefore contributed to an energy density of 64.2 W h kg -1 at a power density of 425 W kg -1 . Moreover, 92.8% of its initial specific capacitance can be maintained after 5000 consecutive cycles (5 A g -1 ). These excellent capacitive properties make NiWO 4 a credible electrode material for high-performance supercapacitors., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The effect of nanosized Al2O3/ZnO fillers on the interactions in PEO-NaSCN polymer electrolytes has been studied by FT-IR, XRD, and DTA measurements. The experimental results are discussed according to the grain boundary effect, the principle of Lewis acid-base, and epitaxial effect. It is shown that the hard Lewis acid centers on the surface of Al2O3 exhibit strong interactions with ether oxygens in PEO, even with ether oxygens that coordinated to Na+. Therefore, the modes of the interaction of Al2O3 with PEO-NaSCN electrolytes are dependent on the salt content. Al2O3 cannot influence the ionic association in P(EO)8NaSCN electrolyte, but do reduce significantly the solvating ability of PEO toward NaSCN in P(EO)60NaSCN electrolyte. However, NaSCN in P(EO)20NaSCN-30%Al2O3 nanocomposite appears as a state that resembles the situation of NaSCN in PEO amorphous phase. In contrast with Al2O3, the epitaxial effect of ZnO is not found in the interested systems where only weaker interaction is observed between ZnO and ether oxygen, and the modes of interaction of ZnO with PEO-NaSCN electrolytes are hardly related to the salt content. In addition, the soft Lewis acid groups on ZnO surface exhibit stronger complexation with SCN- in PEO-NaSCN electrolytes, and both can form the complex anion ZnO...SCN-.