Crucial roles of graphene oxide in preparing alginate/nanofibrillated cellulose double network composites hydrogels.

In this study, a novel strategy to prepare sodium alginate (SA)/nano fibrillated cellulose (NFC) double network (DN) hydrogel beads with the aid of graphene oxide (GO) was developed. In comparison with the multi-step freezing-thawing method, this study employs a facile one-step freeze drying method with the presence of GO sheets. The crucial roles of GO were highlighted as an efficient nucleating agent of NFC and a reinforcer for the hydrogel. The adsorption property of the DN hydrogel towards crystal violet (CV) was also studied. Results indicated that the introduction of GO could greatly facilitate the formation of double networks. Furthermore, the as-prepared DN hydrogel beads exhibited an efficacious adsorption property towards CV. The maximum adsorption capacity of the hydrogels for CV was observed as 665 mg g-1. Therefore, our approach here represents a facile method for the preparation of crystalline polymer based DN hydrogels to replace the awkward freezing-thawing process, giving inspiration for DN hydrogels design and preparation. Moreover, due to its efficient adsorption capacity, the hydrogels hold great promise for the water pollution control materials.

Broadband near-infrared quantum cutting by Ce-Yb codoped YAG transparent glass ceramics for silicon solar cells.

Ce3+-Yb3+ co-doped transparent glass ceramics containing YAG nanocrystals were prepared by a conventional melt-quenching method. Broadband near infrared quantum cutting was achieved in the glass ceramics and proved to be a cooperative down-conversion process. Under 460 nm excitation, 2F5/2 to 5d1 electronic transitions occurred in Ce3+ and transferred their energy to two neighboring Yb3+. The dependence of the luminescence spectra and decay curves on Yb3+ concentration was investigated to understand the energy transfer mechanism. The energy transfer efficiency and the down-conversion quantum efficiency were estimated to be as high as 77.8% and 177.8%, respectively. This work will open a new route towards increased efficiency in silicon solar cells.

Broadband ultraviolet to near infrared conversion in Eu2+,Nd3+ co-doped SrAl2O4.

In this study, we investigated the quantum cutting (QC) mechanism in Eu2+-Nd3-co-doped SrAl2O4 microcrystals by fluorescence spectroscopy and decay lifetime analysis. In this material, the near-infrared (NIR) emissions of Nd3+ in the range of 800-1200 nm were enhanced under the excitation of the Eu2+:4f7 → 4f65d1 transition radiation. The lifetime of the 5d1 level of Eu2+ decreased with the increase in the Nd3+ concentration. These results verified the occurrence of cooperative energy transfer (CET) from the Eu2+:5d1 excited state to the Nd3+:4F3/2 level, by which one absorbed ultraviolet-visible photon was converted to two NIR photons with an optimal quantum efficiency (QE) of approximately 177.1%. Therefore, this broadband QC material paves the way for a further increase in the conversion efficiency of c-Si solar cells.

Poly[tetra-aqua-bis-(µ(4)-thio-phene-2,5-dicarboxyl-ato)(µ(2)-thio-phene-2,5-dicarboxyl-ato)dieuropium(III)].

The three-dimensional coordination polymer, [Eu(2)(C(6)H(2)O(4)S)(3)(H(2)O)(4)](n), has been synthesized under hydro-thermal conditions. The asymmetric unit comprises one Eu(3+) cation, two aqua ligands and one and a half thiophene-2,5-dicarboxylate anions (the half-anion being completed by a twofold rotation axis). The Eu(3+) cation is eight-coordinated in a distorted dodeca-hedral geometry. The crystal structure features O-H⋯O hydrogen bonds.

Adsolubilization of dihydroxybenzenes into CTAB layers on silica particles.

The adsolubilization of dihydroxybenzenes (catechol and hydroquinone) into cetyltrimethylammonium bromide (CTAB) layers on silica particles have been investigated by dye method and UV spectrum. It is found that the adsolubilization amount of catechol increases with increasing the concentration of CTAB, reaches a maximum value at the critical micelle concentration (CMC), and then decreases with further increment of CTAB concentration. For hydroquinone, different phenomenon is observed. The maximum adsolubilization amount reaches at critical surface aggregation concentration (CSAC) instead of CMC of the CTAB and then decreases to constant values. In order to analyze the adsolubilization difference between catechol and hydroquinone, we determined the interaction between them and CTAB in the bulk solution by measuring the diffusion coefficient of dihydroxybenzenes with ultramicroelectrode (UME). The individual contributions to the overall apparent diffusion coefficient of dihydroxybenzenes in CTAB solutions were also calculated. The results indicate that more hydroquinone than catechol could interact with CTAB molecules. However, rarely hydroquinone could interact with CTAB micelles compared with catechol. It is suggested that the substitution positions of hydroxyl lead to the difference of the interaction between dihydroxybenzenes and CTAB, which is responsible for the difference of the adsolubilization.