Dye-sensitized solar cells: A safe bet for the future.

This review describes the main features of dye-sensitized solar cells (DSCs) and highlights recent breakthroughs in this promising thin-film photovoltaic (PV) technology. After a brief presentation of the commercially available technologies, the general operation principles and the most relevant characteristics of DSCs are summarized. Recent major advances in high efficiency sensitizers, nanostructured semiconductors and robust electrolytes offer an opportunity for DSCs integration into the marketplace. With attractive features, like low-cost potential, simple processing, wide range of applicability - from low-power electronics to semi-transparent windowpanes for electricity generation - and good performance under typical operating conditions, these cells are one step from large-scale commercialization. We describe major strategies that are under way to make DSCs a key technology in the future PV paradigm

Preparation of well-dispersed chitosan/alginate hollow multilayered microcapsules for enhanced cellular internalization

Hollow multilayered capsules have shown massive potential for being used in the biomedical and biotechnology fields, in applications such as cellular internalization, intracellular trafficking, drug delivery, or tissue engineering. In particular, hollow microcapsules, developed by resorting to porous calcium carbonate sacrificial templates, natural-origin building blocks and the prominent Layer-by-Layer (LbL) technology, have attracted increasing attention owing to their key features. However, these microcapsules revealed a great tendency to aggregate, which represents a major hurdle when aiming for cellular internalization and intracellular therapeutics delivery. Herein, we report the preparation of well-dispersed polysaccharide-based hollow multilayered microcapsules by combining the LbL technique with an optimized purification process. Cationic chitosan (CHT) and anionic alginate (ALG) were chosen as the marine origin polysaccharides due to their biocompatibility and structural similarity to the extracellular matrices of living tissues. Moreover, the inexpensive and highly versatile LbL technology was used to fabricate core-shell microparticles and hollow multilayered microcapsules, with precise control over their composition and physicochemical properties, by repeating the alternate deposition of both materials. The microcapsules' synthesis procedure was optimized to extensively reduce their natural aggregation tendency, as shown by the morphological analysis monitored by advanced microscopy techniques. The well-dispersed microcapsules showed an enhanced uptake by fibroblasts, opening new perspectives for cellular internalization.publishe

Erratum: Development of Poly(l-Lactic Acid)-Based Bending Actuators. Polymers 2020, 12, 1187

The authors wish to make a change to their published paper [1]. In the original manuscript, there is a mistake in a sentence in Section 3.5, on page 10. Two words “anions and cations” were reverted by mistake. The corrected sentence is shown below: The strain developed as a response to the applied electrical field results from the diffusion of the ions and migration to the positive (anions) and negative (cations) electrode layers, and subsequent accumulation close to the electrodes. The authors apologize for any inconvenience caused, and the change does not affect the scientific results. The manuscript will be updated, and the original will remain online on the article webpage at https://www.mdpi.com/2073-4360/12/5/1187.(undefined

Development of poly(l-Lactic Acid)-based bending actuators

This work reports on the development of bending actuators based on poly(l-lactic acid) (PLLA)/ionic liquid (IL) blends, through the incorporation of 40% wt. of the 1-ethyl-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim][TFSI]) IL. The films, obtained by solvent casting at room temperature and 50 °C, were subjected to several post-thermal treatments at 70, 90, 120 and 140 °C, in order to modify the crystallinity of the films. The influence of the drying temperature and of [Emim][TFSI] blending on the morphological, structural, mechanical and electrical properties of the composite materials were studied. The IL induced the formation of a porous surface independently of the processing conditions. Moreover, the [Emim][TFSI] dopant and the post-thermal treatments at 70 °C promoted an increase of the degree of crystallinity of the samples. No significant changes were observed in the degree of crystallinity and Young Modulus for samples with thermal treatment between 70 and 140 °C. The viability of the developed high ionic conductive blends for applications as soft actuators was evaluated. A maximum displacement of 1.7 mm was achieved with the PLLA/[Emim][TFSI] composite prepared at 50 °C and thermally treated at 140 °C, for an applied voltage of 10 Vpp, at a frequency of 100 mHz. This work highlights interesting avenues for the use of PLLA in the field of actuators.The authors thank the FCT—Fundação para a Ciência e Tecnologia—for financial support under the Strategic Funding UID/FIS/04650/2020, and PEST-C/QUI/UIO686/2019, the Associated Laboratory Research Unit for Green Chemistry, Technologies and Clean Processes, LAQV (financed by national funds from FCT/MEC, UID/QUI/50006/2020 and ERDF under the PT2020, POCI-01-0145-FEDER-007265) and projects PTDC/BTM-MAT/28237/2017 and PTDC/EMD-EMD/28159/2017. DMC and LCF also thank the grants SFRH/BPD/121526/2016 and SFRH/BD/145345/2019, respectively

LITHIUM-DOPED SILK FIBROIN FILMS FOR APPLICATION IN ELECTROCHROMIC DEVICES

Abstract Silk fibroin (SF) is a commonly available natural biopolymer produced in specialized glands of arthropods, with a long history of use in textile production and also in health cares. The exceptional intrinsic properties of these fibers, such as self-assembly, machinability, biocompatibility, biodegradation or non-toxicity, offer a wide range of exciting opportunitie

Methyl 2-(4,6-dichloro-1,3,5-triazin-2-yl­amino)acetate

The title compound, C6H6Cl2N4O2, was prepared by the nucleophilic substitution of 2,4,6-trichloro-1,3,5-triazine by glycine methyl ester hydro­chloride, and was isolated from the reaction by using flash chromatography. The crystal structure at 150 K reveals the presence two crystallographically independent mol­ecules in the asymmetric unit which differ in the orientation of the pendant methoxy­carbonyl group. Each mol­ecular unit is engaged in strong and highly directional N—H⋯N hydrogen-bonding inter­actions with a symmetry-related mol­ecule, forming supra­molecular dimers which act as the synthons in the crystal packing

β-ketoenamine covalent organic frameworks—effects of functionalization on pollutant adsorption

Water pollution due to global economic activity is one of the greatest environmental concerns, and many efforts are currently being made toward developing materials capable of selectively and efficiently removing pollutants and contaminants. A series of β-ketoenamine covalent organic frameworks (COFs) have been synthesized, by reacting 1,3,5-triformylphloroglucinol (TFP) with different C2-functionalized and nonfunctionalized diamines, in order to evaluate the influence of wall functionalization and pore size on the adsorption capacity toward dye and heavy metal pollutants. The obtained COFs were characterized by different techniques. The adsorption of methylene blue (MB), which was used as a model for the adsorption of pharmaceuticals and dyes, was initially evaluated. Adsorption studies showed that –NO2 and –SO3H functional groups were favorable for MB adsorption, with TpBd(SO3H)2-COF [100%], prepared between TFP and 4,4′-diamine- [1,1′-biphenyl]-2,2′-disulfonic acid, achieving the highest adsorption capacity (166 ± 13 mg g−1). The adsorption of anionic pollutants was less effective and decreased, in general, with the increase in –SO3H and –NO2 group content. The effect of ionic interactions on the COF performance was further assessed by carrying out adsorption experiments involving metal ions. Isotherms showed that nonfunctionalized and functionalized COFs were better described by the Langmuir and Freundlich sorption models, respectively, confirming the influence of functionalization on surface heterogeneity. Sorption kinetics experiments were better adjusted according to a second-order rate equation, confirming the existence of surface chemical interactions in the adsorption process. These results confirm the influence of selective COF functionalization on adsorption processes and the role of functional groups on the adsorption selectivity, thus clearly demonstrating the potential of this new class of materials in the efficient and selective capture and removal of pollutants in aqueous solutions.This work was funded by the Coimbra Chemistry Centre (CQC), which is supported by the Fundação para a Ciência e a Tecnologia (FCT), Portugal, through the grants ref. UID/QUI/00313/2020 and ref. UI/BD/150809/2020, co-funded by COMPETE2020-UE

Nanofluid Based on Glucose‐Derived Carbon Dots Functionalized with [Bmim]Cl for the Next Generation of Smart Windows

The design of new advanced materials and technologies is essential for the development of smart windows for the next generation of energy‐efficient buildings. Here, it is demonstrated that the functionalization of glucose‐derived carbon dots with 1‐butyl‐3‐methylimidazolium chloride results in a self‐standing, water‐soluble, viscous, reusable nanofluid with self‐improving conductivity, thermotropy around 30–40 °C, and ultraviolet blocking ability. Its synthesis is straightforward, clean, fast, and cheap. At 36 °C (hot summer day), a sun‐actuated thermotropic (TT) device incorporating a 95% w/w nanofluid aqueous solution exhibits a transmittance variation (ΔT ) of 9% at 550/1000 nm, which is amplified to 47/31% via the surface plasmon resonance effect. An integrated self‐healing system enabling independent sun‐actuated TT and voltage‐actuated electrochromic (EC) operation is also produced. The low‐energy EC device offers bright hot and dark cold modes (ΔT = 68/64%), excellent cycling stability, unprecedented coloration efficiency values (−1.73 × 106/−1.67 × 106 cm2 C−1 (coloring) and +1.12 × 107/+1.08 × 107 cm2 C−1 (bleaching) at ±2.5 V), and impressive memory effect. The disruptive design and sustainable synthesis of the new nanofluid proposed here will foster the agile development of novel products with improved ecological footprint.This research was funded by the National Funds by Foundation for Science and Technology (FCT) and by the FEDER funds through POCI-COMPETE 2020-Operational Programme Competitiveness and Internationalization in Axis I: Strengthening research, technological development and innovation (UID/QUI/00616/2013, UID/QUI/50006/2019, UID/Multi/00709/2013, UID/QUI/00313/2019, UID/CTM/50025, POCI-01-0145-FEDER-007491, POCI-01-0145-FEDER-007688, UID/CTM/50025, POCI-01-0145-FEDER-016884, PTDC/CTM-NAN/0956/2014, SAICT/PAC/0032/2015, POCI-01-0145-FEDER-016422, and NORTE-01-0145-FEDER-030858). R.F.P.P. acknowledges FCT-MCTES for SFRH/BPD/87759/2012 grant. R. Rego and M. Fernandes (UTAD, Vila Real) and E. Pereira (FCUP, Porto) are acknowledged for their assistance.info:eu-repo/semantics/publishedVersio

Glycine methyl ester hydro­chloride

The title compound [systematic name: (methoxy­carbonyl­meth­yl)ammonium chloride], crystallizes as a salt, C3H8NO2 +·Cl−, with the charged species inter­acting mutually via strong and highly directional N+—H⋯Cl− hydrogen bonds which lead to the formation of a supra­molecular tape running parallel to the c axis. Tapes close pack in the solid state mediated by multipoint recognition synthons based on weak C—H⋯O inter­actions and van der Waals contacts between adjacent methyl groups

Solar spectral management with electrochromic devices including PMMA films doped with biluminescent ionosilicas

The technological potential of poly(methyl methacrylate) (PMMA)-based composite films doped with lanthanide-doped sol–gel derived ionosilicas (IS-Ln) previously proposed for luminescent down-shifting (LDS) and luminescent solar concentrator (LSC) layers connected to photovoltaic (PV) cells is extended here to electrochromic devices (ECDs), targeting the fabrication of single energy harvesting/conversion/management LSC-LDS/PV/ECD systems. These integrated devices have foreseen application in the windows of future zero-energy buildings of smart cities. The proof-of-concept is given with the report of the electro-optical performance of an ECD comprising an optimized electrolyte film composed of PMMA, IS-Nd, and IS-Eu, and the 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid. This amorphous electrolyte is stable below 160 °C, exhibits high ionic conductivity (2.13 × 10−4 and 8.76 × 10−4 S cm−1 at room temperature and 44 °C, respectively), and emits in the visible (red color) and near-infrared (NIR) spectral regions. The device demonstrated fast switching speed (50 s) and high transparency in the visible-to-NIR spectral regions (transmittance (T) = 79/96/89/77% at 555/1000/1500/1650 nm in the as-prepared state, respectively). Upon application of ±2.5 V for 200 cycles, at the same wavelengths, the Tbleached/Tcolored values were 44/28, 46/26, 39/20, and 27/9%, respectively, and the coloration efficiency (CE) values CEin/CEout values were −302/+181, −381/+228, −446/+267 and −734/+440 cm2 C−1, respectively.publishe