An ultrathin highly fluorinated porous membrane was designed for a large production of desalted water at very low energy consumption. Imprinting water droplets were used through a low thermally conductive tetra-fluoroethylene (TFE)/2,2,4-trifluoro-5-tri-fluorometoxy-1,3-dioxol (TIT) (HYFLON AD 60) solution and the generated porous nanofilm was suspended onto a polyethersulfone (PES) honeycomb texture. The very tiny fluorinated thickness together with a large number of small-shaped pores provided the membrane for enhanced anti-wetting surface properties, extremely reduced resistance to water vapor transfer and outstanding thermal efficiency. Fine materials structure-transport relations let the membrane reach unusual productivity-efficiency trade-off during water desalination via thermally driven membrane distillation. The exceptional performance affords this novel nanostructured membrane to catalyze the accomplishment of new-concept water desalination processes. Graphical abstract Download : Download high-res image (165KB) Download : Download full-size image

Ionic liquids (ILs) and ionic liquid-nanoparticle (IL-NP) hybrid electrolytes have garnered a lot of interest due to their unique properties that stimulate their use in various applications. Herein, we investigate the electrochemical and photo-physical properties of organic-inorganic hybrid electrolytes based on three imidazolium-based ionic liquids, i.e., 1-buthyl-3-methylimidazolium thiocyanate ([bmim] [SCN]), 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim] [BF4]) and 1-buthyl-3-methylimidazolium acetate ([bmim] [Ac]) that are covalently tethered to amorphous porous silicon nanoparticles (ap-Si NPs). We found that the addition of ap-Si NPs confer to the ILs a pronounced boost in the electrocatalytic activity, and in mixtures of ap-Si NPs and [bmim] [SCN], the room-temperature current transport is enhanced by more than 5 times compared to bare [bmim] [SCN]. A detailed structural investigation by transmission electron microscope (TEM) showed that the ap-Si NPs were well dispersed, stabilized and highly aggregated in [bmim] [SCN], [emim] [BF4] and [bmim] [Ac] ILs, respectively. These observations correlate well with the enhanced current transport observed in ap-Si NPs/[bmim] [SCN] evidenced by electrochemical measurements. We interpreted these observations by the use of UV–vis absorbance, photoluminescence (PL), FTIR and solid-state NMR spectroscopy. We found that the ap-Si NPs/[bmim] [SCN] hybrid stands out due to its stability and optical transparency. This behavior is attributed to the iron(III) thiocyanate complexion as per the experimental findings. Furthermore, we found that the addition of NPs to [emim] [BF4] alters the equilibrium of the IL, which consequently improved the stability of the NPs through intermolecular interactions with the two ionic layers (anionic and cationic layers) of the IL. While in the case of [bmim] [Ac], the dispersion of ap-Si NPs was restrained because of the high viscosity of this IL. Graphical abstract Download : Download high-res image (193KB) Download : Download full-size image

Highlights • The scope of manufacturing low-cost conductive functional devices using a desktop 3D printer is discussed. • Several polymer materials are analyzed and developed a new conductive polymer nanocomposites (PBT/CNT and PBT/G) for desktop 3D printing applications. • The printability, esthetics and functional properties of PBT/CNT and PBT/G 3D printed composites are discussed. • Strategies to 3D printing multi-materials (printing more than one material – “integrated printing”) is discussed. • Nozzle wear and challenges in using abrasive conductive fillers (like CNT and graphene) are discussed. Fused deposition modeling (FDM) is limited by the availability of application specific functional materials. Here we illustrate printing of non-conventional polymer nanocomposites (CNT- and graphene-based polybutylene terephthalate (PBT)) on a commercially available desktop 3D printer leading toward printing of electrically conductive structures. The printability, electrical conductivity and mechanical stability of the polymer nanocomposites before and after 3D printing was evaluated. The results show that 3D printed PBT/CNT objects have better conductive and mechanical properties and a better performance than 3D printed PBT/graphene structures. In addition to that, printing more than one material (multi-materials) and challenges in using abrasive conductive fillers (i.e., CNT and graphene) are also discussed. Overall this study demonstrates that a commercially available desktop 3D printer can be used to fabricate low-cost functional objects. Graphical abstract Download : Download high-res image (254KB) Download : Download full-size image

Carbon black nanoparticles (CBNPs) press imprinted films are proposed for class-selective electrochemical detection of ortho-diphenols (o-diphenols) and mono-phenols (m-phenols) antioxidants. In order to optimize the sensor construction, different surface immobilizations of CBNPs electroactive films on a PMMA support were assayed by using different amounts of CBNPs dispersions. The best sensor in terms of selectivity, sensitivity and stability was obtained when 30 mL of a CBNPs dispersion (0.50 mg/100 mL in 1,2-dichloroethane) were transferred onto PMMA substrates applying a pressure of 4.6 ton. The electrodes were characterized by Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry (CV) to explore their electrical properties. The effective transfer of CBNPs on the PMMA support and the CBNPs film conductivity have been evaluated by Atomic Force Microscopy (AFM) confirming that the carbon black film is effectively imprinted on the polymer surface and that retains its good conductivity. X-ray Photoelectron Spectroscopy (XPS) and Raman spectroscopy have been employed to investigate the CBNPs composition and the CBNPs electrode surface, respectively. CBNPs electrodes exclusively supported the o-diphenols and m-phenols sensing, at low detection potentials (+0.100 and +0.560 V, respectively) and with negligible surface fouling (peak intensity RSDs <12% and oxidation potential <6%, n = 28). Class-selective electrochemical indexes (EIs) for o-diphenols and m-phenols are proposed for the evaluation of the phenols antioxidant contents in complex samples such as olive oils. Graphical abstract Download : Download high-res image (102KB) Download : Download full-size image

Cell encapsulation in 3D microgels offers unique advantages to meet the complicated requirements in tissue engineering, regenerative medicine and cell therapy. Herein we report high-throughput microfluidic generation of cell-laden microgels based on a new hyaluronic acid (HA) derivative, i.e. furylamine and tyramine grafted HA molecules, which can be crosslinked via either enzymatic crosslinking, or Diels–Alder click chemistry, or both. Compared with traditional photoinitiated free radical polymerization and Michael conjugate addition reaction, enzymatic crosslinking and click chemistry crosslinking show higher chemical selectivity and milder reaction conditions. More importantly, the switching of crosslinking strategy in the same molecule makes it possible to fabricate microgels with almost the same composition but variable gelation time and elasticity. Using ATDC-5 cells as model cells, three types of cell-laden microgels were generated in high-throughput manner and their potentials as cell carriers were evaluated in detail by comparing their mechanical elasticity, gelation time, microgel size, swelling ratio, cell viability, enzymatic degradation and bioactivity of released cells. Our results reveal that the new HA-derived microgels crosslinked by enzymatic crosslinking and Diels–Alder click chemistry are very promising candidate for cell encapsulation and delivery. Graphical abstract Download : Download high-res image (143KB) Download : Download full-size image

Polycrystalline silicon nitride (Si3N4), sintered with the addition of minor fractions of yttrium and aluminum oxides (i.e., Y2O3 and Al2O3), possesses uniquely adjustable surface chemistry that results in improved cell metabolism and enhanced bone formation. Building upon previous in vitro mineralization studies using osteosarcoma cells, this study examined interactions between various chemically modulated Si3N4 surfaces and murine mesenchymal progenitor cells (KUSA-A1). It was discovered that various pressurized thermal-treatments coupled with adiabatic and non-adiabatic cooling of sintered Si3N4 samples resulted in partial or full coverage of their surfaces with different Si–Y–O–N compounds. Full coverage by mostly yttrium silicate (β-Y2Si2O7) was obtained by non-adiabatic cooling, whereas partial coverage with N-apatite (Y10(SiO4)6N2) occurred under adiabatic conditions. These peculiar phases were found to be particularly efficient in stimulating the in vitro differentiation of KUSA-A1 cells into osteoblasts, although according to different microscopic mechanisms. The final amount of bone formation was nearly identical for both phases. Cell differentiation was monitored by assessing the concentration of the osteogenic marker γ-carboxyglutamate (i.e., Gla-osteocalcin). It was found to be ∼45% higher for Si3N4 samples possessing the N-apatite phase than for biomedical titanium alloy controls tested under exactly the same conditions. Concurrent measurements of the bone resorption marker Glu-osteocalcin (i.e., an undercarboxylated form of γ-carboxyglutamate) showed significant inhibition of osteoclastogenesis on these surface-treated Si3N4 samples as compared to the controls. Bone formation was assessed using in situ Raman microprobe spectroscopy and ex situ laser microscopy. These two independent analytical techniques consistently found an increase of ∼80% in expressed hydroxyapatite when compared to a biomedical titanium alloy. This study suggests that surface-treated Si3N4 may have a powerful anabolic, differentiating, and antiapoptotic effect on osteoblasts in vitro, and a concurrent inhibitive action on osteoclastogenesis. Given additional research, Si3N4 may represent a new therapeutic solution for bone disorders and for engineered implants that physiologically regulate bone growth processes. Graphical abstract Download : Download high-res image (257KB) Download : Download full-size image

We have demonstrated a flexible force-controlled contact electrification field-effect transistor (CE-FET). The pn CE-FET was fabricated on a flexible PET (polyethylene terephthalate) substrate using the p-type poly(3-hexylthiophene) (P3HT), and the n-type phenyl-C61-butyric acid methyl ester (PCBM) films as a conductive channel in the CE-FET. The PEO polyethylene oxide (–CH2CH2O–, PEO) was then deposited on the surface of the conductive channel to act as a contact layer. When the mobile electrode was progressively touched with the PEO contact layer, a triboelectric potential was significantly created between them. This potential can self-generate a gate signal to modulate the charge carrier transport in the conductive channel of the CE-FET and thereby provide a prospective control of its output current. The PTFE (polytetrafluoroethylene, PTFE) and the porous SiO2 film (made from the recycling rice husks) was used as a mobile electrode in the enhancement mode and the depletion mode of the CE-FET, respectively, in order to build in an inner electric field by the triboelectric potential between the contact layer and the mobile electrode. Through controlling the distance between the two frictional layers, the output current of the pn CE-FET can be dramatically modulated from 2.84 nA to 62.31 nA in the enhancement mode, while that of the current can be controlled from 17.26 nA to 2.84 nA in the depletion mode. The pn CE-FET has provided high perspectives and opportunities for the flexible electronic devices applications in future. Graphical abstract We have demonstrated a flexible force-controlled contact electrification field-effect transistor (CE-FET) by the conductive polymer thin film. The pn CE-FET can self-generate the internal electric fields which can effectively modulate the bias voltage of the CE-FET to control the output current by tuning the distance between the mobile electrode and contact surface. The CE-FET is able to open up a prodigious possibility for the future engineering applications in the field of flexible tribotronic devices and active sensor. Download : Download high-res image (129KB) Download : Download full-size image

It has been demonstrated for the first time that high-entropy alloys can be synthesised by electrochemical reduction in a molten salt. This was accomplished by means of an electrolytic cell in which pre-mixed solid metal oxides were subjected to cathodic polarisation in an electrolyte of molten CaCl2 salt at 1173 K, such that the equiatomic refractory alloys TiNbTaZr and TiNbTaZrHf were produced in a single-step alloying process. Structural investigations revealed that the TiNbTaZr alloy comprises two body-centred cubic phases while the TiNbTaZrHf alloy has one disordered body-centred cubic phase. Further examinations were carried out to assess the alloys’ morphological and mechanical properties. These novel findings promise a straightforward, low-energy and cost-affordable electrometallurgical process for the production of high-entropy alloys for advanced structural applications. Graphical abstract Schematic representation of synthesis of high-entropy alloy by electrochemical deoxidation of metal oxide mixture in a molten salt. Download : Download high-res image (104KB) Download : Download full-size image

Very thin TiO2 blocking layers (BLs) are important components for achieving high solar power conversion efficiencies (PCEs) in the dye-sensitized solar cells, and particularly perovskite solar cells (PSCs). When reasonably thin, TiO2 BLs prevent recombination of photogenerated charges at the conductive fluorine-doped tin oxide (FTO) glass substrate used in these devices. However, all previous attempts to generate efficient TiO2 BLs have been hampered by an insufficient charge transfer rate at quasi-amorphous TiO2 and very low thermal stability, leading to the loss of blocking properties after thermal calcination. In this work, we report the deposition of homogenous very thin (∼30 nm) TiO2 BLs by combining advanced high impulse power magnetron sputtering (HiPIMS) and additional bipolar medium-frequency (MF) magnetron co-sputtering. The as-deposited TiO2 films were shown to provide excellent blocking properties which were preserved even after thermal treatment at 450 °C. Moreover, TiO2 BLs thermally treated at 450 °C show a well-developed rutile structure and 70 times higher photocurrents compared to the as-deposited layers. This work opens possibilities for the utilization of very thin TiO2 layers in solar cell technologies providing a double mode of action: blocking functionality and efficient electron transport. Graphical abstract Download : Download high-res image (139KB) Download : Download full-size image