Organic/inorganic thermoelectric composites have played an important role in the development of new, green, and renewable energy sources with potential applications in efficient thermal management, flexible electronics, and bioelectronics. Electrochemical syntheses, including electropolymerization, electrochemical deposition, electrochemical doping, electrochemical post-processing, etc., require no addition of surfactants or oxidants, the products of which are easy to separate and purify, providing clean, efficient, and facile routes for the preparation of organic thermoelectric materials and their composites. In this review, the preparation, properties, and applications of organic/inorganic thermoelectric composites from electrochemical synthesis were reviewed in detail, offering a perspective on the recent advances in the field.
Graphical abstractIn this critical note, the thermal stability behavior of ultra-fine grained (UFG) and nano-structured (NS) metals and alloys produced through severe plastic deformation (SPD) techniques is reviewed. For this case, the common engineering metals with body-centered cubic (BCC), face-centered cubic (FCC), and hexagonal close-packed (HCP) crystal structures such as aluminum, copper, nickel, magnesium, steel, titanium, and their relating alloys were assessed. Microstructural evolution in these severely deformed materials following post-processing annealing treatment was investigated for various times and temperatures below the recrystallization point. The microstructure development reported in the literature was studied in terms of the stable grain structures correlated with different levels of plastic straining. The stacking fault energy (SFE) is noted to be a key issue which has a critical influence in predicting the coalescence or coarsening behavior of ultra-fine and nanoscale grains after SPD treatment by controlling the cross-slip phenomenon for screw dislocations.
Graphical AbstractSilver nanowires find use in a myriad of applications, including communication systems, sensors, medical devices and electrical equipment. Temperature-dependent electrical and thermal properties of chemically derived silver nanowires are rarely explored. In the present work, seed-mediated synthesis of silver nanowires has been carried out, and their electrical and thermal conductivity at 300 K is found to be 1.848?×?107 S/m and 64.8 W/mK, respectively. A screen-printable ink of silver nanowires is formulated and printed on low-cost and widely used substrates like paper and cotton fabrics. Flexible printed electrodes could be made possible with uniform printed structures obtained in cotton fabric and paper substrate. The printed pattern exhibited sheet resistance of 0.7 Ω/sq. Screen-printed silver nanowires on paper show shielding efficiency of 99.9% in X band, which promotes them as excellent candidates in fabricating lightweight electronic devices by a one-step printing process.
Graphical abstractAquivion membrane displays improved properties as compared to Nafion membrane, partly due to shorter side chains. However, some improvements are still necessary for proton exchange membrane fuel cell to operate at low relative humidity. To overcome this drawback, the addition of clay nanoparticle into the Aquivion matrix can be considered. In this study, different composite membranes have been prepared mixing short-side-chain PFSA (perfluorosulfonic acid) Aquivion and selectively modified halloysite nanotubes for PEMFC low relative humidity operation. Halloysites were grafted with fluorinated groups, sulfonated groups, or perfluoro-sulfonated groups on inner or outer surface of the tubes. The obtained composite membranes showed improved properties, especially higher water uptake associated with reduced swelling and better mechanical strength compared to pristine Aquivion membrane and commercially available Nafion HP used as reference. The best performance in this study was obtained with Aquivion loaded with 5 wt% of pretreated perfluoro-sulfonated halloysite. The composite membrane, referred to as Aq/pHNT-SF5, displayed the largest water uptake and proton conductivity among the panel of membranes tested. The chemical stability was not affected by the presence of halloysite in the Aquivion matrix.
Graphical abstractNon-dendritic microstructures are generally obtained in metals after semi-solid deformation (deformation during solidification); however, dendritic growth is preferred without deformation. The fragmentation of dendrites is recognized as an essential contributing factor to non-dendritic microstructures. However, the underlying mechanism of fragmentation needs to be clarified in depth. It is infamously hard for researchers to carry out a direct observation of this process. Moreover, a comprehensive numerical survey of this process is not trivial. The present research reported a new method to model dendritic growth during semi-solid deformation. The motion and deformation of the solid coupled with liquid flow in the melt were treated as the two-phase flow because plastic materials could be formulated as non-Newtonian fluids. The vector-valued phase-field formulation and the self-constructed Navier–Stokes solver made it possible to simulate the growth, motion, deformation, fragmentation and agglomeration of two dendrites coupled with liquid flow in the melt. Computational results suggest that fragmentation can occur when the grain boundary is wet and penetrated by the melt, giving new supporting evidence to a previously proposed mechanism for the fragmentation of dendrites.
Graphical abstractThe development of eco-friendly connection material instead of steel is a challenging problem in timber structures. Following densification, the mechanical properties of low-density species can be significantly improved. Densified wood may be a potential connection material in timber structures. This paper reviewed the different processing for densified wood, and obtained favorable mechanical properties and dimensional stability based on small specimen sizes, which are much less than the applicable sizes in practice. A densification processing with alkali pretreatment was adopted for poplar widely cultivated in the world to produce the densified poplar, which has been rarely reported as connection material. Various specimens of densified poplar were tested to obtain their main mechanical properties such as strength and deformability. The set recovery of densified poplar was also measured to observe their dimensional stability. In addition, the hygroscopic swelling strains for the diameter of densified poplar dowel were measured to present their moisture-dependent behavior. The improved mechanical properties and dimensional stability confirmed the fact that densified poplar with alkali pretreatment can be an optimal connection material.
Graphical abstractThe caloric effects under combined applications of magnetic field and hydrostatic pressure to a MnCoSi meta-magnet were investigated. Under a magnetic field change of 0–5 T, the maximum magnetic entropy change was enhanced by 35.7% when a 3.2kbar hydrostatic pressure was applied, and the cooling temperature span was extended by 60 K when a hydrostatic pressure of 9.7 kbar was applied. The coupled caloric entropy change, which originates from the coupling between the magnetism and volume, was calculated and accounted for the enhanced entropy change of MnCoSi. The present work facilitates the use of MnCoSi as a solid-state refrigerant and also enriches the investigation of the multicaloric effect under multiple external fields.
Graphical abstractWO3, a visible light reaction catalyst, absorbs light at a wavelength of 470 nm and has many advantages, such as strong stability, long life, non-toxicity, low cost, and suitable band edges. In this review, the photocatalytic mechanism of WO3 in water pollution treatment is introduced, as well as a systematic summary, and some main strategies for improving the photocatalytic activity of WO3 in water pollution treatment are introduced, for example surface and morphology control, synthetic heterojunctions, and doping element. Finally, the main conclusions and prospects of WO3-based photocatalysts are pointed out. It can be expected that this review can provide guidance for designing low-cost, high-efficiency new WO3-based photocatalysts in the process of water pollution treatment and can meet the application prospects of efficient utilization of solar degradation in the field of environmental purification.
Graphical abstractHybrid organic–inorganic nanocomposites are great candidates for display and illumination systems due to improved optoelectronic properties and photostability. This work endeavours towards the scientific study of the influence of defect-induced zinc oxide nanoparticles (ZnO) on the optical characteristics of poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV). ZnO nanoparticles consist of many vacancies which facilitate light emission across the visible region. The green defective emission occurring due to the presence of oxygen vacancies in ZnO was used to re-excite MEH-PPV and hence, improve the luminescence quantum efficiency. The photostability of the nanocomposite was enhanced through charge transfer (prevents the formation of superoxides) and energy transfer (reduces the non-radiative decay) mechanisms.
Graphical abstractIn view of the disadvantages of concentration polarization and trade-off effects in the application of membrane in desalination field, oxide-nano graphene oxide/polyamide (O-NGO/PA) loose intermediate layer and PA ultra-thin dense layer were introduced to fabricate PA/O-NGO/polyphenylene sulfide composite membrane with sandwich structure via multi-step interfacial polymerization (MS-IP) method. The selective permeation mechanism of ultrathin layer produced by different aqueous monomers (PIP and MPD) was studied, the effect of its physicochemical structure on the relief of concentration polarization phenomenon and the breakthrough of trade-off effect was analyzed. The ultra-thin and dense PA layer mainly played the role of interception and shortened the water molecular penetration path. In the retention test of metal salt solution, compared with the rough surface, it was found that the smooth surface was more conducive to the diffusion of intercepted metal ions into the feed solution, thus alleviating the concentration polarization phenomenon.
Graphical abstractWe review the literature describing the use of interleaves to increase interlaminar fracture toughness in fibre-reinforced polymer composites and hence to improve damage tolerance. From an analysis of data provided in the literature from the use of microfibre and nanofibre interleaves, we show that the performance of these widely researched systems is clearly differentiated when plotted against the mean coverage of the interleaf. Using a simple analysis, we suggest that this can be attributed to the influence of their porous architectures on the infusion of resin. We show also that the superior toughening performance of microfibre interleaves is only weakly influenced by the choice of fibre. We find also that the inclusion of carbon nanotubes within interleaves to deliver multifunctional composites can be optimised by using a hybrid system with microfibres.
Graphical abstractPolyimide aerogels are promising for diverse applications owing to their nanoporous structure and superior performance in thermal insulation, dielectric protection, etc. However, the severe shrinkage they usually suffer has long been a threat, and can pose great challenges to their shape-stable preparation and reliable applications. It is very important to clarify the effects of various factors on the shrinkage of PI aerogels and the effective strategies available for shrinkage reduction. These are also the focuses of the present review, to provide guidance for preparing PI aerogels with greatly reduced shrinkage, and thereby improved shape stability and use reliability. Since the shrinkage of PI aerogels is quite a complex issue, further studies on PI aerogels against shrinkage deserve continuous attention.
Graphical abstractNovel thermal nanoparticles [hollow mesoporous silica nanospheres (HMSNs)–poly (N-isopropyl acrylamide-acrylic acid) PNIPAM-AA] were developed with Ag nanoparticles (AgNps) as the core, mesoporous silica nanoparticles as the layer, and thermally responsive polymers PNIPAM-AA as the shell. The AgNps had good photothermal effects, PNIPAM-AA was responsive to temperature, the combination of AgNps and PNIPAM-AA could be used as a photothermal-responsive switch for drug release, and HMSNs greatly increased the drug loading of the carrier. The samples were characterized by means of scanning electron microscopy, transmission electron microscopy, N2 adsorption–desorption, thermogravimetric analysis, Fourier transform infrared spectroscopy, and UV–Vis absorption spectra. The results showed that Ag@HMSN nanoparticles possessed a uniform diameter (330 nm), high specific surface area (822.45 m2/g), and mesoporous pore size (2.75 nm). Using ibuprofen (IBU) as a model drug, the release process was monitored under in vitro conditions to investigate its release characteristics at different temperatures. The results showed that the nanoparticles had a significant regulatory effect on IBU release.
Graphical abstractThe development of hydrogen production via environment-friendly and efficient electrochemical water splitting technology leans heavily on the exploitation of highly active and durable oxygen evolution reaction (OER) electrocatalysts. Herein, nanocoral-like cerium-activated cobalt selenide (Ce-CoSe2) nanocomposites to enhance the OER catalytic activity have been successfully prepared by one-pot hydrothermal route via simply altering the cerium content. Owing to the ingenious introduction of cerium, as-prepared Ce-CoSe2 electrode displays remarkable OER performance in comparison with CoSe2. The nanocoral-like Ce-CoSe2 catalyst prepared under optimal condition just needs low overpotential of 276 and 398 mV at 10 and 50 mA cm?2, respectively. Additionally, it attains the current density of 255 mA cm?2 at the potential of 2.0 V vs. RHE, and shows long-term stability during OER. This work offers a simple and feasible pathway for the design and construct of metal dichalcogenides for green and renewable hydrogen production by electrocatalytic water splitting.
Graphical abstractExtension of corrosion inhibitors from traditional molecular-scale to nanoscale will not only be significant to develop green and efficient inhibitors, but also supplement the discipline system of corrosion inhibitors. However, many research on the interfacial behavior of nano-inhibitors have ignored the special colloidal properties of nanoparticles and show no obvious differences with traditional inhibitors. In this study, graphene oxide (GO) was functionalized with polydopamine (PDA) via covalent modifications and self-polymerization, and GO-PDA was studied as a corrosion inhibitor of carbon steel in HCl solution. Diversified measurements confirmed that GO-PDA can effectively protect carbon steel from corrosion, and the inhibition efficiency almost reached 90% at 100 mg/L. Interfering factors including immersion time and concentration were investigated. The lamellar nanoparticles adsorbed on the surface of carbon steel have formed a hydrophobic film in micro-nano structures. The transition from a negative charge on the GO surface to a positively charged GO-PDA contributed to adsorption at the interface. An initial model of nano-inhibitor was established to explicate the inhibition mechanism.
Graphical abstractOxygen-containing carbon materials have been studied extensively because of their excellent dispersibility, absorptivity, separability, and supportability of catalysts. However, structural control by existing top-down methods is almost impossible. Our group has demonstrated that phloroglucinol (PG, 1,3,5-trihydroxybenzene) can be a promising raw material to synthesize structurally controlled oxygen-containing carbon materials. In this study, in addition to PG, hexahydroxybenzene (HHB), which has more oxygen and high symmetry, was used as the raw material, and a Lewis acid catalyst, tris (pentafluorophenyl) borane (TPB), was used to enhance the structural control rate and the removability of catalysts from the carbonized samples. The solubility of heat-treated HHB was lower than that of heat-treated PG, but the oxygen content of heat-treated HHB was higher than that of heat-treated PG even at 673 K. By adding TPB to PG, dibenzofuran-like structures formed, and the structural control rate increased up to 93.6%. Besides, the content of fluorine in the catalyst was reduced to 0%, indicating that TPB can be a promising recyclable catalyst to promote the structural control rate of carbonized PG.
Graphical abstractPlanar perovskite solar cells (PSCs) have excellent photoelectric properties and show great commercialization potential. However, there are a lot of crystal defects in the perovskite films prepared by solution method, which reduces the development process of solar cells. In this work, alizarin red s (ARS) was doped into MAPbI3 films to passivate the defect. It was shown that the addition of ARS increased the quality of perovskite film and doped perovskite film exhibited improved light absorption. In addition, it was found that there was a strong interaction between ARS and perovskite, which reduced the density of defect states. The results showed that the passivated perovskite device had improved PL intensity, increased carrier lifetimes and reduced charge recombination. After passivation, the device obtained a higher open-circuit voltage (VOC) of 1.103 V where the control device was 1.055 V, and the best power conversion efficiency (PCE) of the doped device was 18.82%, which is 11.36% higher than that of the control device of 16.90%.
Graphical abstractOxygen evolution reaction (OER) for water splitting has a sluggish kinetics, thus significantly hindering the reaction efficiency. So far, it is still challenging to develop a cost-efficient and highly active catalyst for OER processes. To address such issues, we design and synthesize NiP2/FeP heterostructural nanoflowers interwoven by carbon nanotubes (NiP2/FeP@CNT) by a hydrothermal reaction followed by phosphating. The NiP2/FeP@CNT catalyst delivers excellent OER performance: it displays an ultralow Tafel slope of 44.0 mV dec?1 and a relatively low overpotential of 261 mV at 10 mA cm?2, better than RuO2 commercial catalyst; it also shows excellent stability without observable decay after 20-h cycling. The outstanding OER property is mainly attributed to its special 3D stereochemical structure of CNT-interwoven NiP2/FeP heterostructural nanoflowers, which is highly conductive and guarantees considerable active sites. Such nanostructure greatly facilitates the charge transfer, which significantly improves its electrocatalytic activity. This work offers a simple method to synthesize non-precious transition metal-based phosphide electrocatalysts with a unique hierarchical nanostructure for water splitting.
Graphical abstractNanotechnologies known as a developing applied science have significant global socioeconomic values and many advantages obtained from nanoscale materials. Its applications can have significant effects on the performance of organizations. The advance of two-dimensional (2D) MXene-derived QDs (MQDs) is currently in the initial stages. Scholars have shown distinguished optical, electronic, thermal and mechanical attributes by surface chemistry and versatile transition metal. In this field of study, many applications are introduced like energy electromagnetic interference shielding, storage, sensors, transparent electrodes, photothermal therapy, catalysis and so on. The vast range of optical absorption attributes of MQDs along with high electronic conductivity has been detected to be key attributes because of their achievement in the mentioned usages. Currently, relatively little materials are highly known because of their basic electronic and optical properties, which can limit their full potentials. From a theoretical and experimental point of view, in this work, electronic and optical properties of MQDs along with applications corresponding to those properties were evaluated.
Graphical abstractReactive oxygen species (ROS) refers to the reactive molecules and free radicals of oxygen generated as the by-products of aerobic respiration. Historically, ROS are known as stress markers that are linked to the response of immune cell against microbial invasion, but recent discoveries suggest their role as secondary messengers in signal transduction and cell cycle. Tissue engineering (TE) techniques have the capabilities to harness such properties of ROS for the effective regeneration of damaged tissues. TE employs stem cells and biomaterial matrix, to heal and regenerate injured tissue and organ. During regeneration, one of the constraints is the unavailability of oxygen as proper vasculature is absent at the injured site. This creates hypoxic conditions at the site of regeneration. Hence, effective response against the stresses like hypoxia spurs the regeneration process. Contrary, hyperoxic condition may increase the risk of ROS stress at the site. TE tries to overcome these limitations with the new class of biomaterials that can sense such stresses and respond accordingly. This review endeavors to explain the role of ROS in stem cell proliferation and differentiation, which is a key component in regeneration. This compilation also highlights the new class of biomaterials that can overcome the hypoxic conditions during tissue regeneration along with emphasis on the ROS-responsive biomaterials and their clinical applications. Incorporating these biomaterials in scaffolds development holds huge potential in tissue or organ regeneration and even in drug delivery.
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