Ultrathin two-dimensional materials for photo- and electrocatalytic hydrogen evolution

Sustainable hydrogen production via photocatalytic, electrocatalytic, and synergetic photoelectrocatalytic processes has been regarded as an effective strategy to address both energy and environmental crises. Due to their unique structures and properties, emerging ultrathin two-dimensional (2D) materials can bring about promising opportunities to realize high-efficiency hydrogen evolution. This review presents a critical appraisal of advantages and advancements for ultrathin 2D materials in catalytic hydrogen evolution, with an emphasis on structure–activity relationship. Furthermore, strategies for tailoring the microstructure, electronic structure, and local atomic arrangement, so as to further boost the hydrogen evolution activity, are discussed. Finally, we also present the existing challenges and future research directions regarding this promising field.     

The rich photonic world of plasmonic nanoparticle arrays

Metal nanoparticle arrays that support surface lattice resonances have emerged as an exciting platform for manipulating light–matter interactions at the nanoscale and enabling a diverse range of applications. Their recent prominence can be attributed to a combination of desirable photonic and plasmonic attributes: high electromagnetic field enhancements extended over large volumes with long-lived lifetimes. This Review will describe the design rules for achieving high-quality optical responses from metal nanoparticle arrays, nanofabrication advances that have enabled their production, and the theory that inspired their experimental realization. Rich fundamental insights will focus on weak and strong coupling with molecular excitons, as well as semiconductor excitons and the lattice resonances. Applications related to nanoscale lasing, solid-state lighting, and optical devices will be discussed. Finally, prospects and future open questions will be described.     

Synthesis of porous nanododecahedron Co3O4/C and its application for nonenzymatic electrochemical detection of nitrite

Porous nanododecahedron of Co₃O₄/C has been synthesized by calcination of the ZIF-67 in air at 400 °C and then be used as electrode material for fabricating a highly sensitive and low overpotential sensor of nitrite ion (NO₂^?). The structure and morphology characterization show that ZIF-67 behaves as an ideal sacrificial template for preparing Co₃O₄/C with regular shape. The two components of Co₃O₄ and carbon are uniformly distributed in the composite. Electrochemical analysis shows that the excellent electrocatalysis performance toward the oxidation of NO₂^? is based on the synergy of Co₃O₄ and carbon in the nanocomposite. At NO₂^? concentration from 2 nM to 8 mM, a fast response time within 3 s is revealed and 1.21 nM of detection limit is achieved. The sensor is also reliable to analysis of NO₂^? existed in the real samples of soil leaching liquid and macrophage supernate.     

Practical strategy to produce ultrafine ceramic glaze: Introducing a polycarboxylate grinding aid to the grinding process

In this work, a polycarboxylate comb-like polymer was used as grinding aid for ceramic slurry, and the effect of addition of this grinding aid on ceramic process property was highlighted. The grinding efficiency of the polycarboxylate grinding aid (PG) in terms of the particle size distribution and specific surface of unit volume of the ceramic slurry being ground were investigated. Consequently, the PG that was synthesized via free radical polymerization under the condition of an APEG/AA/MA molar ratio of 0.3:1:1, an initiator dosage of 5 wt%, and a reaction time of 6 h at 90 °C, provided better grinding efficiency than those of the triethanolamine and other commercial grinding aids. Specifically, with a dosage of 0.21% and 2 h of grinding, the d₉₇ and d₅₀ of ceramic slurry decreased from 13.956 μm and 2.043 µm to 3.739 µm and 0.561 µm, respectively. The cumulative distribution, frequency distribution and SEM results exhibited a uniform particle size distribution for ceramic ground with PG-C. Furthermore, the sintering experiment indicated that a lower processing temperature was capable of producing ultrafine ceramic. These improvements indicated the potential application of the PG as an efficiency ceramic grinding aid, which further facilitating the preparation of uniform ultrafine slurry by a sand mill.     

Multi-electron reaction materials for sodium-based batteries

Sodium-based rechargeable batteries are very promising energy storage and conversion systems owing to their wide availability and the low cost of Na resources, which is beneficial to large-scale electric energy storage applications in future. In the context of attempting to achieve high-energy densities and low cost, multi-electron reaction materials for both cathodes and anodes are attracting significant attention due to high specific capacities involved. Here, we present a brief review on recently reported multi-electron reaction materials for sodium-based batteries. We mostly concentrate on true multi-electron reactions that involve individually valence changes greater than one per redox center, but in addition include materials in the discussion, which undergo multi-electron processes per formula unit. The theoretical gravimetric and volumetric (expanded state) capacities are studied for a broad range of examples. Then, the practically achievable volumetric energy density and specific energy of Na cells with hard carbon, sodium (Na), and phosphorus (P) anodes are compared. For this purpose, various data are recalculated and referred to the same basis cell. The results show the potential superiority of the cells using multi-electron reaction materials and provide an intuitive understanding of the practically achievable energy densities in future Na-based rechargeable batteries. However, these multi-electron reaction materials are facing several key challenges, which are preventing their high-performance in current cells. In order to overcome them, general strategies from particle design to electrolyte modification are reviewed and several examples in both cathode and anode materials using such strategies are studied. Finally, future trends and perspectives for achieving promising Na-based batteries with better performance are discussed.     

Interface affected zone for optimal strength and ductility in heterogeneous laminate

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Energy transduction ferroic materials

Ferroic materials and multiferroics, characterized by their ferroic orders, provide an efficient route for the coupling control of magnetic, mechanical, and electrical subsystems in energy transduction, which aims at converting one form of energy into another. A surge of interest in the ferroic coupling effect has stemmed from its potential use as a new versatile route for energy transduction. Here, the recent progress on the use of (multi)ferroic materials is reviewed, with special emphasis on the fundamental mechanisms that dictate the energy transduction process, including piezoelectricity, pyroelectricity, electrocaloric, magnetostriction, magnetocaloric, elastocaloric, magnetoelectricity, and emerging spin-charge conversion. Research on energy transduction ferroic materials paves the way for ubiquitous energy harvesting through magneto-mechano-electric-thermal coupling mechanisms. Finally, a summary and the future prospective directions of this field are discussed.     

Recent advances in emerging 2D nanomaterials for biosensing and bioimaging applications

The great success of graphene throws new light on discovering more two-dimensional (2D) layered nanomaterials that stem from atomically thin 2D sheets. Compared with a single element of graphene, emerging graphene-like 2D materials composed of multiple elements that possess more versatility, greater flexibility and better functionality with a wide range of potential applications. In this review, we provide insights into the rapidly emerging 2D materials and their biosensing and bioimaging applications in recent three years, including 2D transition metal nanomaterials, graphitic nitride materials, black phosphorus, and emerging 2D organic polymers. We first briefly highlight their unique 2D morphology and physicochemical properties and then focus on their recent applications in electrochemical biosensing, optical biosensing and bioimaging. The challenges and some thoughts on future perspectives in this field are also addressed.     

Multiple heterojunction system of Bi2MoO6/WO3/Ag3PO4 with enhanced visible-light photocatalytic performance towards dye degradation

Multiple heterojunction system of Bi₂MoO₆/WO₃/Ag₃PO₄ was designed via constructing binary heterojunction Bi₂MoO₆/WO₃, followed by the deposition of nano-Ag₃PO₄ on the surface of Bi₂MoO₆/WO₃. Various techniques were employed to characterize the properties of the as-prepared catalytic system. In this study, the decomposition efficiency of C.I. reactive blue 19 (RB-19) was used as a measure of photocatalytic activity and the Bi₂MoO₆/WO₃/Ag₃PO₄ composite exceeded its stand-alone components (pristine Ag₃PO₄, WO₃/Ag₃PO₄ and Bi₂MoO₆/Ag₃PO₄) by 3.16 times, 2.63 times and 1.75 times, respectively. The photocatalytic tests implied that the construction of multiple heterojunction could achieve efficient separation of photo-generated electrons and holes. A possible photocatalytic mechanism for Bi₂MoO₆/WO₃/Ag₃PO₄ system was also proposed according to the results of trapping experiments.     

Eggshell nano-particle potential for methyl violet and mercury ion removal: Surface study and field application

A nano-scale sorbent was produced from eggshell wastes for sorption of Hg(II) and methyl violet (MV) from aqueous solutions and real wastewaters. The properties of the nano-particles were fully determined using SEM, DLS, FTIR, XRD, BET, TGA, AFM, EDAX, mapping, and TEM analyses. The adsorbent structure mainly contained carbonate and silica. The effects of influential parameters including temperature, contact time, initial contaminants concentration, sorbent dose, and initial pH on the removal efficiency were investigated. The maximum sorption efficiency of Hg(II) and MV occurred at pH of 6 and 9 and temperatures of 25 °C and 55 °C, respectively. Freundlich model could be interpreted the equilibrium data of the sorption process of both contaminants. The maximum sorption capacity of Hg(II) and MV using eggshell nano-particles was obtained as 116.27 mg/g and 123.45 mg/g, respectively. The dynamic behavior of the process was studied using two kinetic models. The sorption system performance was also examined and t_1/2 were determined as 4.34 min for Hg(II) and 4.97 min for MV. The sorption process of Hg(II) and MV was exothermic and endothermic, respectively. Effective sorption after seven cycles and successful treatment of landfill leachate and textile wastewater with eggshell nano-particles confirms its adequacy.     

Enhanced photocatalytic degradation performance of organic contaminants by heterojunction photocatalyst BiVO4/TiO2/RGO and its compatibility on four different tetracycline antibiotics

Photocatalytic performance of four tetracycline antibiotics using BiVO₄/TiO₂/RGO composites was investigated. To make full use of catalysis, optimum preparation conditions involved RGO content, solution pH and hydrothermal temperature on the structure forming of BiVO₄/TiO₂/RGO composites were investigated. Subsequently, the obtained visible light-driven photocatalyst was used to degrade four kinds of tetracycline antibiotics involved tetracycline (TC), chlortetracycline (CTC), oxytetracycline (OTC) and doxycycline (DXC) for wastewater treatment. Results showed that BiVO₄/TiO₂/RGO photocatalyst exhibited excellent photocatalytic activity and high compatibility due to the enhanced separation efficiency of photo-generated carriers with high reduction and oxidation capability. The degradation process of four kinds of tetracycline antibiotics was traced and detected through identifying intermediates produced in the reaction system. And a possible catalytic mechanism for BiVO₄/TiO₂/RGO photocatalyst was put forward based on band gap structure of BiVO₄ and TiO₂.     

Investigation of the fabric evolution and the stress-transmission behaviour of sands based on X-ray μCT images

This paper presents the use of X-ray micro-tomography (X-ray $\mu$CT) and image processing and analysis techniques to investigate the stress transmission and buckling of inter-particle contacts within a granular material. A triaxial testing of a miniature Leighton Buzzard sand (LBS) sample was carried out with full-field in-situ X-ray $\mu$CT scanning. High-spatial-resolution CT images of the sample were acquired at several loading stages of the test. Image processing and analysis techniques were used to quantify the inter-particle contact evolution (contact gain, contact loss and contact movement), fabric, contact duration and buckling of stress-transmission contacts based on the CT images. The results indicated that contact gain and loss, and contact movement played two competing roles in determining the overall fabric evolution of the sample. Contacts with a longer duration were more likely to orient in the major principal stress direction and form a stress-transmission contact network. A gradual decrease in the buckling rate of the stress-transmission contacts was observed outside of the shear band, and a relatively stable buckling rate was observed within the shear band during the shear. The results suggested that jamming occurred outside of the shear band and that unjamming occurred within the shear band.     

Metallic nanoparticles for cancer immunotherapy

Cancer immunotherapy, or the utilization of the body’s immune system to attack tumor cells, has gained prominence over the past few decades as a viable cancer treatment strategy. Recently approved immunotherapeutics have conferred remission upon patients with previously bleak outcomes and have expanded the number of tools available to treat cancer. Nanoparticles – including polymeric, liposomal, and metallic formulations – naturally traffic to the spleen and lymph organs and the relevant immune cells therein, making them good candidates for delivery of immunotherapeutic agents. Metallic nanoparticle formulations, in particular, are advantageous because of their potential for dense surface functionalization and their capability for optical or heat-based therapeutic methods. Many research groups have investigated the potential of nanoparticle-mediated delivery platforms to improve the efficacy of immunotherapies. Despite the significant preclinical successes demonstrated by many of these platforms over the last twenty years, only a few metallic nanoparticles have successfully entered clinical trials with none achieving FDA approval for cancer therapy. In this review, we will discuss preclinical research and clinical trials involving metallic nanoparticles (MNPs) for cancer immunotherapy applications and discuss the potential for clinical translation of MNPs.     

Study on decolorization of Rhodamine B by raw coal fly ash catalyzed Fenton-like process under microwave irradiation

Coal fly ash (CFA) catalyzed Fenton-like process was studied under microwave (MW) irradiation for the decolorization of Rhodamine B (RhB) wastewater. The physical-chemical properties of CFA were characterized, including the specific surface area, micromorphology, chemical and crystal components, and the distribution and chemical valence of metallic elements. The metallic oxidants in the CFA indicate CFA can work as Fenton-like catalyst and MW-absorbent simultaneously. The results reveal OH is more significant in the decolorization of RhB than HO₂ and O₂^?. The generation of more OH in the MW-Fenton-like process (293–326 K) than that in the conventional heated Fenton-like process (326 K) reflects the function of hot spot effect and possible non-thermal effect of MW. Under the optimum condition ([H₂O₂] 2 mmol L^?1, [CFA] 15 g L^?1, pH 3, P_MW 0.1 kW), the decolorization rate reaches 91.6% after 20 min. The intrinsic kinetic model of RhB decolorization is $-\frac{\mathrm{d}{C}_{\mathrm{R}\mathrm{h}\mathrm{B}}}{\mathit{dt}}={1.76\times 10}^{-4}·C_{\mathrm{R}\mathrm{h}\mathrm{B}}·C_{{\mathrm{H}}_2{\mathrm{O}}_2}^{1.89}·C_{\mathrm{C}\mathrm{F}\mathrm{A}}^{1.97}-\mathrm{d}{\mathrm{C}}_{\mathrm{R}\mathrm{h}\mathrm{o}\mathrm{d}\mathrm{a}\mathrm{m}\mathrm{i}\mathrm{n}\mathrm{e}\mathrm{B}}/\mathrm{d}\mathrm{t}=1.76\times {10}^{-4}·{\mathrm{C}}_{\mathrm{R}\mathrm{h}\mathrm{o}\mathrm{d}\mathrm{a}\mathrm{m}\mathrm{i}\mathrm{n}\mathrm{e}\mathrm{B}}·{\mathrm{C}}_{{\mathrm{H}}_2{\mathrm{O}}_2}^{1.89}·{\mathrm{C}}_{\mathrm{c}\mathrm{o}\mathrm{a}\mathrm{l}\mathrm{f}\mathrm{l}\mathrm{y}\mathrm{a}\mathrm{s}\mathrm{h}}^{1.97}$. The loss of catalytic metallic elements causes the decline of catalytic capacity of CFA. The energy consumption (4313.3 kW·h kg^?1 RhB) is a limitation for the MW-Fenton-like process, which can be overcame by the safe application of nuclear energy. The intermediates and the path of RhB decolorization were detected and proposed, respectively.     

The preparation of surfactant-free highly dispersed ethylene glycol-based aluminum nitride-carbon nanofluids for heat transfer application

In the present study, aluminum nitride-carbon (AlN-C) nanocomposites are synthesized through a green, facile and inexpensive mechanochemical route. Well-dispersed nanofluids are prepared by milling of nanocomposite in ethylene glycol (EG) without using any surfactants/ dispersants. The resulting nanofluids have an excellent stability with no obvious sedimentation for at least three months. The results confirm the in-situ polymerization of EG on AlN surface and the formation of hyperbranched glycerol upon milling which in turn stabilizes the particles through a steric effect. The working nanofluids with very low loadings of up to 0.22 vol% of powder exhibit an enhanced heat transfer coefficient (h) of about 24% compared to that of the base fluid in a laminar flow regime (Re = 160). Brownian motion and boundary layer thinning are known as the main mechanisms, causing for this enhancement.     

Rapid continuous 3D printing of customizable peripheral nerve guidance conduits

Engineered nerve guidance conduits (NGCs) have been demonstrated for repairing peripheral nerve injuries. However, there remains a need for an advanced biofabrication system to build NGCs with complex architectures, tunable material properties, and customizable geometrical control. Here, a rapid continuous 3D-printing platform was developed to print customizable NGCs with unprecedented resolution, speed, flexibility, and scalability. A variety of NGC designs varying in complexity and size were created including a life-size biomimetic branched human facial NGC. In vivo implantation of NGCs with microchannels into complete sciatic nerve transections of mouse models demonstrated the effective directional guidance of regenerating sciatic nerves via branching into the microchannels and extending toward the distal end of the injury site. Histological staining and immunostaining further confirmed the progressive directional nerve regeneration and branching behavior across the entire NGC length. Observational and functional tests, including the von Frey threshold test and thermal test, showed promising recovery of motor function and sensation in the ipsilateral limbs grafted with the 3D-printed NGCs.     

On the analysis of fracture mechanisms and mechanical behavior of AA5083-based tri-modal composites reinforced with 5 wt.%B4C and toughened by AA5083 and AA2024 coarse grain phases

In this article, the influence of AA2024 and AA5083 coarse grains on mechanical properties and failure mechanisms of AA5083-5wt. %B₄C tri-modal composite has been discussed. AA2024 and AA5083 powders (<100 µm) were added to mechanically milled AA5083-5 wt.%B₄C powders in 25 and 50 wt.% and the mixtures were consolidated using the hot press and hot extrusion techniques. Results indicated that by adding AA2024 and AA5083 powders as coarse grains, hardness and tensile strength of AA5083-5 wt.%B₄C composite decreased but ductility increased. Moreover, by adding AA2024 powders as coarse grains, fracture mode changed and cracks tended to grow through along AA2024/AA5083-5 wt.%B₄C interface rather than being arrested or deflected. It seemed that dislocation mobility and the interface between coarse grains and ultra-fine grains had the main role in determining the mechanical properties and failure mechanisms in tri-modal AA5083-B₄C composites.     

Syngas production via coal char-CO2 fluidized bed gasification and the effect on the performance of LSCFN//LSGM//LSCFN solid oxide fuel cell

Fluidized bed reactor is widely used in coal char-CO_2 gasification. In this work, the production of syngas by using a fluidized bed gasification technique was first investigated and then the effect of the produced syngas on the performance of the solid oxide fuel cell with a configuration of La_(0.4)Sr_(0.6) Co_(0.2)Fe_(0.7)Nb_(0.1)O_(3-δ)//La_(0.8)Sr_(0.2)Ga_(0.83)Mg_(0.17)O_(3-δ)//La_(0.4)Sr_(0.6) Co_(0.2)Fe_(0.7)Nb_(0.1)O_(3-δ)(LSCFN//LSGM//LSCFN)was studied. During the syngas production, we found that the volume fraction of CO increased with the increment of gasification temperature, and it reached a maximum value of 88.8%, corresponding to a composition of 0.76% H_2, 88.8% CO, and 10.44% CO_2, when the ratio of oxygen mass flow rate to that of coal char(MO2/Mchar) increased to 0.29. In the following utilization of the produced syngas in solid oxide fuel cells, it was found that the increasing CO volume fraction in the syngas results in a gradual increase of the peak power density of the LSCFN//LSGM//LSCFN cell. The maximum peak power density of 410 m W/cm~2 was achieved for the syngas produced at 0.29 of M_(O2)/M_(char). In the stability test, the cell voltage decreased by 4% at a constant current density of 0.475 A/cm~2 after 54 h when fueled with the syngas with the composition of 0.76% H2, 88.8% CO, and 10.44% CO_2.It reveals that a carbon deposition with the content of 13.66% in the anode is attributed to the cell performance degradation.     

The core-shell structured Fe-based amorphous magnetic powder cores with excellent magnetic properties

The Fe-based soft magnetic amorphous powder cores (AMPCs) with excellent comprehensive magnetic properties were successfully designed and fabricated using the core-shell structured FeSiBCCr/TiO₂ composite powders. The influence of the concentration of water (H₂O) for the magnetic performance of the AMPCs has been systematically studied based on careful analysis of the process of nucleation and growth of TiO₂ under different H₂O concentration in the reaction system. The growth process for the TiO₂ coating layer with the H₂O concentration in the range of 0.01–0.02 ml/g corresponds to the heterogeneous nucleation phase, while the mixing phase of heterogeneous and homogeneous nucleation occurs when the concentration of H₂O increases to 0.03 ml/g. Optimized soft magnetic properties have been achieved for the AMPCs with H₂O concentration of 0.02 ml/g, including high permeability of 81.5 with a high frequency stability up to 10 MHz, high quality factor of 102 at 530 kHz, low core loss of 42 mW/cm³ at 500 kHz for B_m = 0.01 T, and better DC-bias property of 52% at a bias field of 100 Oe due to the uniform and proper thickness insulation coating layer, which can be used to produce miniature magnetic components for applications in medium and high-frequency fields.     

Dry powder formulation combining bedaquiline with pyrazinamide for latent and drug-resistant tuberculosis

The purpose of this study was to develop an inhalable combination dry powder formulation of bedaquiline and pyrazinamide and study their physicochemical properties and safety since this combination acts synergistically against Mycobacterium tuberculosis while pyrazinamide alone is active against latent TB and bedaquiline alone is active against drug-resistant TB. The cospray-dried powder of bedaquiline and pyrazinamide with 20% w/w of L-leucine consisted of spherical, porous particles of inhalable size with a diameter ≤3.2 µm. The aerosolization efficiency of the combination powder (FPF: >66%) evaluated using a next generation impactor was higher than bedaquiline-only (FPF: 31.3%) and pyrazinamide-only (FPF: 5.1%) powders, which could be due to the differences in the morphology of the powders. The combination powder was stable during storage for one month in a desiccator and 75% RH and also safe to both Calu-3 and A549 cells up to 100 µg/ml. This is the first report on the development of an inhalable combination dry powder formulation of bedaquiline and pyrazinamide with high aerosolization efficiency. This formulation has the potential to improve the treatment of both latent and drug-resistant TB.