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Magnesium hydride (MgH2) is one of the most promising hydrogen storage materials for practical application due to its favorable reversibility, low cost and environmental benign; however, it suffers from high dehydrogenation temperature and slow sorption kinetics. Exploring proper catalysts with high and sustainable activity is extremely desired for substantially improving the hydrogen storage properties of MgH2. In this work, a composite catalyst with high-loading of ultrafine Ni nanoparticles (NPs) uniformly dispersed on porous hollow carbon nanospheres is developed, which shows superior catalytic activity towards the de-/hydrogenation of MgH2. With an addition of 5 wt% of the composite, which contains 90 wt% Ni NPs, the onset and peak dehydrogenation temperatures of MgH2 are lowered to 190 and 242 °C, respectively. 6.2 wt% H2 is rapidly released within 30 min at 250 °C. The amount of H2 that the dehydrogenation product can absorb at a low temperature of 150 °C in only 250 s is very close to the initial dehydrogenation value. A dehydrogenation capacity of 6.4 wt% remains after 50 cycles at a moderate cyclic regime, corresponding to a capacity retention of 94.1%. The Ni NPs are highly active, reacting with MgH2 and forming nanosized Mg2Ni/Mg2NiH4. They act as catalysts during hydrogen sorption cycling, and maintain a high dispersibility with the help of the dispersive role of the carbon substrate, leading to sustainably catalytic activity. The present work provides new insight into designing stable and highly active catalysts for promoting the (de)hydrogenation kinetics of MgH2.

As a promising cathode material, Na3V2(PO4)2F3 (NVPF) has attracted wide attention for sodium-ion batteries (SIBs) because of its high operating voltage and high structural stability. However, the low intrinsic electronic conductivity and insufficient Na ion mobility of NVPF limit its development. Herein, K-doping NVPF is prepared through a facile ball-milling combined calcination method. The effects of K-doping on the crystal structure, kinetic properties and electrochemical performance are investigated. The results demonstrate that the Na2.90K0.10V2(PO4)3F3 (K0.10-NVPF) exhibits a high capacity (120.8 mAh g−1 at 0.1 C), high rate capability (66 mAh g−1 at 30 C) and excellent cycling performance (a capacity retention of 97.5% at 1 C over 500 cycles). Also, the occupation site of K ions in the lattice, electronic band structure and Na-ion transport kinetic property in K-doped NVPF are investigated by density functional theory (DFT) calculations, which reveals that the K-doped NVPF exhibits improved electronic and ionic conductivities, and located K+ ions in the lattice to contribute to high reversible capacity, rate capability and cycling stability. Therefore, the K-doped NVPF serves as a promising cathode material for high-energy and high-power SIBs.

Sustainable development based on the value-added utilization of furfural residues (FRs) is an effective way to achieve a profitable circular economy. This comprehensive work highlights the potential of FRs as precursor to prepare porous carbons for high performance supercapacitors (SCs). To improve the electrochemical performance of FR-based carbon materials, a facile route based on methanol pretreatment coupled with pre-carbonization and followed KOH activation is proposed. More defects could be obtained after methanol treatment, which is incline to optimize textural structure. The activated methanol treated FR-based carbon materials (AFRMs) possess high specific surface area (1753.5 m2 g−1), large pore volume (0.85 cm3 g−1), interconnected micro/mesoporous structure, which endow the AFRMs with good electrochemical performance in half-cell (326.1 F g−1 at 0.1 A g−1, 189.4 F g−1 at 50 A g−1 in 6 M KOH). The constructed symmetric SCs based on KOH, KOH–K3Fe(CN)6 and KOH-KI electrolyte deliver energy density up to 8.9, 9.9 and 10.6 Wh kg−1 with a capacitance retention of over 86% after 10,000 cycles. Furthermore, the self-discharge can be restrained by the addition of K3Fe(CN)6 and KI in KOH electrolyte. This study provides an effective approach for high-valued utilization of FR waste.

With the rapid growth in the number of passenger cars (PCs) in China over the past decades, more than ten million tons of used tires have already become solid wastes and subsequently caused serious environmental issues. Due to the presence of synthetic rubber in PC tires, waste PC tires cannot be disposed through rubber reclaiming technology. Thus, waste PC tires have become one of fastest growing solid wastes in China. First, the current disposal capacity of the pyrolysis method, regarded as a promising technology for the disposal of waste PC tires, is surveyed and compared with other disposal methods mentioned in previous papers. Second, this work establishes a model to predict the total number of waste PC tires in the next five years depending on the rate of PC growth and current waste tire disposal capacity. Moreover, pyrolysis is evaluated on 15 collected waste PC tires selected from the most representative tire brands in the Chinese market. The corresponding results imply that ∼68.5% of S was into oil and ∼44.3% N and large amount of heavy metals resided in solid carbon which severely limit further applications. Finally, a new pyrolysis technology is introduced that may represent a solution to the limits in the application of tire disposal methods and relief for the coming waste tire crisis.

In this study, Mg–6.0Zn–3.0Sn–0.5Mn (ZTM630) magnesium alloy was pre-activated by colloidal Ti, oxalic acid, and phosphoric acid, and a phosphate conversion coating (PCC) was prepared on the alloy surface. The morphology and corrosion resistance of the prepared PCCs were investigated. Surface morphology studies showed that the phosphate crystals that formed the coating were the smallest for the sample pre-activated by phosphoric acid. The coating on the colloidal Ti and the phosphoric acid samples had the largest and the smallest thickness and surface roughness, respectively. The reason for the discrepancy was analyzed by comparing the surface morphologies of alloy samples immediately after the pre-activation treatment and various phosphating treatments. X-ray diffraction analysis revealed that all three PCCs contained the same compounds. The corrosion resistance time from the copper sulfate drop test and the electrochemical data from the potentiodynamic polarization curves showed that the coating pre-activated by phosphoric acid had the best corrosion resistance. Finally, the 1500 h neutral salt spray corrosion test confirmed that the phosphating treated magnesium alloy, which was pre-activated by phosphoric acid, exhibited excellent corrosion resistance and behavior.

In this work, pre-strain annealing strengthening (PSAS) effect was investigated in an extruded Mg-1.0Gd-1.5 Zn (wt.%) alloy with respect to different grain sizes. The evolution of microstructures was provided by scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), transmission electron microscopy (TEM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) under the initial state, pre-compression, intermediate annealing and re-compression conditions. The obtained results showed a grain size-dependent PSAS effect in the alloy. The sample with larger grain sizes corresponded to a higher strengthening effect, which mainly resulted from a more remarkable hindrance for the growth of existing twins and a larger proportion of activation for the nucleation of new twins. This was closely associated with the increase of back stress and friction stress for twin boundary motion impeded by the larger restraint of dislocations, the higher stress field surrounding solutes and the more Zn segregation. In addition to twinning behavior, Guinier Preston (G.P.) zones on basal 〈a〉 dislocations were found after intermediate annealing and provided an extra strengthening by inhibiting the motions of gilding pre-existing dislocations and newly formed ones, but it was independent on the grain size.

In this work, the kinetics of the growth of austenite grains upon heating, the features of the processes of dynamic and static recrystallization occurring at various temperature-deformation modes of plastic deformation are investigated. Phase transformations have been studied during continuous cooling of hotdeformed austenite in low-alloy “Arc”-steel with a yield point of at least 420 MPa. The studies carried out made it possible to determine the thermal deformation parameters that ensure the formation of a finely dispersed homogeneous ferrite-bainitic structure, on the basis of which technological recommendations for industrial production were developed and sheet products were manufactured. Presented are the structure and properties of sheet metal from shipbuilding “Arc”-strength category 420 MPa.

This study discusses the influence of fluidization and gasification parameters on the hydrogen composition in syngas. For gasification conditions, when Stage 1 and Stage 2 gasifier temperature is 900 °C, the hydrogen content in syngas is 35.59 mol.% when the activated carbon is used as bed material. For using zeolite as bed material, the hydrogen content is 38.25 mol.%. The hydrogen content is higher than that under other conditions, but if the Steam/Biomass ratio is increased to 0.6, the hydrogen content resulted from zeolite as bed material is the highest 39.38 mol.%. For fluidization parameters, when Stage 2 bed material size is changed to 0.46 mm, no matter the bed material is activated carbon or zeolite, the hydrogen content in syngas is the best among three particle sizes. In terms of operating gas velocity, when gas velocity is 1.5 Umf, the hydrogen content is higher. For fluidization parameters, the two bed materials can increase hydrogen content in syngas effectively in Stage 2 fluidized bed, and their effects are similar to each other. However, considering the fluidization parameters, the hydrogen content in syngas when activated carbon is used as bed material is better than that when the zeolite is used.

A novel recycling solution for thermoplastic composites (TPCs) was recently implemented. The processing steps comprise shredding of TPC offcuts to flakes of a few centimetres, melting and blending of the flakes in a low-shear mixer, extrusion of a molten mixed dough and subsequent compression moulding in a press. This material and process are similar to the compression moulding of long-fibre thermoplastics (LFTs) that have been in the market for decades, such as glass mat thermoplastics (GMT) or direct-LFT. However, the input material in this recycling route consists of multi-layered woven flakes, which is very different from the pellets or chopped rovings of other LFTs. Process- and material-induced heterogeneities such as fibre orientation, percolation, variation of fibre fraction, or fibre attrition may be different for this new material. The development of this recycling technology and future industrial applications require more confidence in the material and process. The objective of this study is to characterise these heterogeneities for this recycling solution, and compare them to those generated in regular LFTs. It was found that the process- and material-induced heterogeneities of the recycled TPCs are similar to other LFTs, for the aspects listed here: fibre orientation, percolation, variation of fibre fraction and fibre attrition. In comparison to GMT, the effect of the mixing step is particularly noticeable on the local variation of fibre fraction within the panels. Industrial applications of this recycling route will benefit from this similarity, as it improves the confidence in the material and process combination.

A mechanically strong binder with polar functional groups could overcome the dilemma of the large volume change during charge/discharge processes and poor cyclability of lithium-sulfur batteries (LSBs). In this work, for the first time, we report the use of poly(thiourea triethylene glycol) (PTTG) as a multifunctional binder for sulfur cathodes to enhance the performance of LSBs. As expected, the PTTG binder facilitates the high performance and stability delivered by the Sulfur-PTTG cathode, including a higher reversible capacity of 825 mAh g−1 at 0.2 C after 80 cycles, a lower capacity fading (0.123% per cycle) over 350 cycles at 0.5 C, a higher areal capacity of 2.5 mAh cm−2 at 0.25 mA cm−2, and better rate capability of 587 mAh g−1 at 2 C. Such superior electrochemical performances could be attributed to PTTG's strong chemical adsorption towards polysulfides which may avoid the lithium polysulfide shuttle effect and excellent mechanical characteristics which prevents electrode collapse during cycling and allows the Sulfur-PTTG electrode to maintain robust electron and ion migration pathways for accelerated redox reaction kinetics.

A comparative analysis of typical stress-strain diagrams obtained for in-plain shear of the 25 unidirectional and cross-ply reinforced polymer matrix composites under quasi-static loading was carried out. Three of them were tested in the framework of this study, and the experimental data on other materials were taken from the literature. The analysis of the generalized shear-strength curves showed that most of the tested materials exhibit the similar deformation pattern depending on their initial shear modulus: a linear section is observed at the beginning of loading, whereas further increase of the load decreases the slope of the curve reaching the minimum in the failure point. For the three parameters (end point the linear part, maximum reduced deviation of the diagram, tangent shear modulus at the failure point) characterizing the individual features of the presented stress-strain diagrams, approximating their dependences on the value of the reduced initial shear modulus are obtained. At the characteristic points of the deformation diagrams, boundary conditions are determined that can be used to find the parameters of the approximating functions. A condition is proposed for determination of the end point of the linear section on the experimental stress-strain curve, according to which the maximum deviation between the experimental and calculated (according to Hooke’s law) values of the shear stress in this section is no more than 1%, thus ensuring rather high accuracy of approximation on the linear section of the diagram. The results of this study are recommended to use when developing universal and relatively simple in structure approximating functions that take into account the characteristic properties of the experimental curves of deformation of polymer composite materials under in-plane shear of the sheet. The minimum set of experimental data is required to determine the parameters of these functions.

Transition metal sulfides (TMSs) have been regarded as greatly promising electrode materials for supercapacitors because of abundant redox electroactive sites and outstanding conductivity. Herein, we report a self-supported hierarchical Mn doped Co9S8@Co(OH)2 nanosheet arrays on nickel foam (NF) substrate by a one-step metal–organic-framework (MOF) engaged approach and a subsequent sulfurization process. Experimental results reveal that the introduction of manganese endows improved electric conductivity, enlarged electrochemical specific surface area, adjusted electronic structure of Co9S8@Co(OH)2 and enhanced interfacial activities as well as facilitated reaction kinetics of electrodes. The optimal Mn doped Co9S8@Co(OH)2 electrode exhibits an ultrahigh specific capacitance of 3745 F g−1 at 1 A g−1 (5.618 F cm−2 at 1.5 mA cm−2) and sustains 1710 F g−1 at 30 A g−1 (2.565 F cm−2 at 45 mA cm−2), surpassing most reported values on TMSs. Moreover, a battery-type asymmetric supercapacitor (ASC) device is constructed, which delivers high energy density of 50.2 Wh kg−1 at power density of 800 W kg−1, and outstanding long-term cycling stability (94% capacitance retention after 8000 cycles). The encouraging results might offer an effective strategy to optimize the TMSs for energy-storage devices.

Photothermal therapy becomes a hotspot in the treatment of bone tumors. Magnesium and its alloys are regarded as potential bone implants for their favorable mechanical property and biodegradable in vivo. However, there is few research devoted to fabricating a photothermal coating on Mg alloy. In the present study, reduced graphene oxide coating with a strong photothermal effect was prepared on the surface of AZ31 via two steps. Firstly, graphene oxide coating was deposited on the surface via electrophoresis deposited (GO#), followed by a reduction process of the graphene oxide coating in ultrapure water (rGO#). GO# and rGO# coatings were characterized by SEM, Raman, XRD, FTIR, and XPS. The results revealed that, compared with GO# coating, the content of oxygen-containing (C O/C O-C, C=O, O C=O) groups on rGO# coating was significantly decreased. rGO# coating was found tightly adhered to AZ31 substrate. According to the first-principles calculations, the well-bonded heterostructure between MgO and rGO is the main reason for the strong bonding force. Moreover, the prepared rGO# coating showed a superior photothermal effect, which brings a new strategy to the treatment of bone tumors with Mg-based implants.

Protein adsorption preferentially occurs and significantly affects the physicochemical reactions once the biodegradable magnesium alloys as bone replacements have been implanted. To date, interactions mechanisms between Mg implants and proteins remain unclear at a molecular level. Thereby, a combination of molecular dynamic (MD) simulations and experimental exploration is used to investigate the adsorption behavior and conformational change of bovine serum albumin (BSA), a representative protein of blood plasma, upon the surface of micro-arc oxidation (MAO) coated Mg alloy AZ31. The influences of absorbed proteins on the cytocompatibility of MAO coating are evaluated by virtue of cytotoxicity assay. Results indicate that the negatively charged O atoms (BSA) exhibit strong interaction with Mg2+ ions of Mg(OH)2, revealing that BSA molecules are ionically adsorbed on the AZ31 surface. Interestingly, MD simulation reveals that MAO coating demonstrates superior ability to capture BSA molecules during the process of adsorption owing to strong electric attraction between the negatively charged O atoms in BSA molecules with Mg atoms of MgO in MAO coating. Moreover, the α-helix part of absorbed BSA molecules on AZ31 substrate and MAO coating markedly decreases with an increase in β-sheet, β-turn and unordered contents, which is attributed to the reduction in the number of hydrogen bonds in BSA molecules. Furthermore, the adsorbed BSA molecules improve the cytocompatibility of MAO coating since the positively charged -NH3+ group and β-sheet content of absorbed BSA molecules mediate the cell adhesion by interacting with the negatively charged cell membrane.

A powder thixoforging route combined with slurry based mixing process was proposed to fabricate graphene nanoplatelets (GNPs) reinforced magnesium matrix composites (MgMCs). The originally spherical and ball-milled ZK60 powders were used as matrices, respectively. The mixing of 0.05 wt.% GNPs with the spherical powder led to GNPs clusters and degraded the mechanical properties of the composite. In contrast, with the addition of an optimal content (0.1 wt.%) of GNPs, the composite fabricated from ball-milled powder achieved a joint enhancement in tensile yield strength (52%) and fracture toughness (19%), demonstrating a pronounced strengthening efficiency of 650% and a good balance between strength and toughness. The ball-milled powder endowed the composite with a homogenous distribution of GNPs and a denser microstructure with reduced Mg-Zn eutectics, and the thixoforging process offered a well-bonded Mg/GNP interface, making full use of the strengthening and toughening potential of GNPs. Theoretical predication based on a modified shear-lag model suggested that load transfer dominated the strengthening mechanisms. In-situ tensile tests verified that crack deflection, secondary cracks and GNPs bridging mainly accounted for the toughening mechanisms. A numerical model with consideration of GNPs orientations was also established to understand the toughening effect from GNPs bridging.

Corrosion behavior of AZ31 magnesium alloy in NH4+-bearing chloride solution with controlled pH was investigated by weight loss experiment, hydrogen collection, and electrochemical test combined with surface morphology and topography observation. The results show that NH4+ and pH of the solution can affect the corrosion of AZ31 magnesium alloy. The existence of NH4+ affects the formation and dissolution of corrosion products, which makes the protective effect of the corrosion product layer weaker. The change of pH value not only affects the corrosion mechanism of AZ31, but also alters the concentration of NH4+ ions in the solution, which further influences the corrosion product layer of AZ31, and finally makes the corrosion of AZ31 change significantly.

The long-period stacking ordered phases (LPSOs) in Mg−Ni−Y system have been attracting great interest as effective strengthening components because of their unique structural characteristics and deformation mechanism. However, the phase relationships in LPSOs are complicated and unclear, which restricts the design of advanced magnesium-based alloys. The aim of the present work is to experimentally determine the phase equilibria relationships focusing on LPSOs and establish the thermodynamic description for Mg−Ni−Y system. Four types of LPSOs, that is, 14H, 12R, 18R and 10H, are confirmed through equilibrated alloys and high-resolution transmission electron microscopy (HR-TEM). The formation enthalpies of LPSOs (14H, 12R, 18R and 10H) are calculated based on density functional theories (DFT) calculations. A new ternary compound, termed as τ phase, is observed for the first time which is likely to be the distorted structure of 12R as determined from the TEM image which shows a 12-layer closed packing plane distance of 3.252 nm and a shear angle of 83.2° between (0002) and (10 1 ¯ 0) planes. Based on the determined phase equilibria relationship, the Mg−Ni−Y system is assessed and a self-consistent description is obtained where the LPSOs are modeled as the stoichiometric compounds. The comparison between the calculation result and experimental data suggests the accuracy of the present thermodynamic database in the Mg-rich corner.

The microstructure of primary Mg 2 Si and the interface of Mg 2 Si / α -Mg modified by Sn and Sb elements in an as-cast Mg-5Sn-2Si-1.5Al-1Zn-0.8Sb (wt.%) alloy were investigated. In the primary Mg 2 Si phase not only the Si atoms but also the Mg atoms could be substituted by Sn and Sb atoms, resulting in the slightly reduced lattice constant a of 0.627 nm. An OR of Mg 2 Si phase and α -Mg in the form of [ 001 ] Mg 2 Si ∥ [ 01 1 ¯ 1 ] α , ( 220 ) Mg 2 Si ∥ ( 0 1 ¯ 12 ) α was discovered. Between primary Mg 2 Si phase and α -Mg matrix two transitional nano-particle layers were formed. In the rim region of primary Mg 2 Si particle, Mg 2 Sn precipitates sizing from 5 nm to 50 nm were observed. Adjacent to the boundary of primary Mg 2 Si particle, luxuriant columnar crystals of primary Mg 2 Sn phase with width of about 25 nm and length of about 100 nm were distributed on the α -Mg matrix. The lattice constant of the Mg 2 Sn precipitate in primary Mg 2 Si particle was about 0.756 nm. Three ORs between Mg 2 Sn and Mg 2 Si were found, in which the Mg 2 Sn precipitates had strong bonding interfaces with Mg 2 Si phase. Three new minor ORs between Mg 2 Sn phase and α -Mg were found. The lattice constant of primary Mg 2 Sn phase was enlarged to 0.813 nm owing to the solution of Sn and Sb atoms. Primary Mg 2 Sn had edge-to-edge interfaces with α -Mg. Therefore, the primary Mg 2 Si particle and α -Mg were united and the interfacial adhesion was improved by the two nano-particles layers of Mg 2 Sn phase.

Well-ordered hierarchically mesoporous/microporous carbon materials have been successfully fabricated by using dual soft-templating approach through compressed CO2. Pluronic F127 and different type of surfactants, including nonionic, cationic, and anionic surfactants, were used as dual templates to investigate the influence on the morphology and nanostructure of the as-prepared carbon samples. TEM, SEM, N2 sorption, wide-angle and small-angle XRD analysis were employed to reveal the well-ordered hierarchically micro-mesoporous structure with 2D hexagonal symmetry by using compressed CO2. The prepared HPC samples with different pressures as the catalyst carriers have been functioned by chlorosulfonic acid for the fructose conversion into HMF. Chlorosulfonic acid concentration, catalyst dosage and reaction temperature have been optimized for fructose-to-HMF transformation with the obtained catalyst. The performances of as-made HPC–SO3H samples in HMF yield and reaction rate of fructose-to-HMF transformation have been investigated. The stability of the samples was also conducted in the dehydration of fructose to HMF for five cycles. The possible catalytic mechanism by using hierarchically porous carbon materials as catalyst support for fructose-to-HMF transformation was proposed.

An interesting phenomenon was found that fluorophore was introduced into ionic liquid (IL) to magnify fluorescence signal via the thermally activated delayed fluorescence process; thus up to 15 fold enhancements were achieved. Hence, we reported a succinct enhanced luminescence strategy to reduce single-triplet energy split by the tunability of ILs. This strategy could be extended to more kinds of ILs by the virtue of a preliminary DFT calculation screening. Moreover, the optical feature of IL sensor made it a promising candidate as a gas fluorescence sensor.

Emerging evidence shows that some Lactobacillus fermentum strains can contribute to the prevention and treatment of ulcerative colitis (UC). In this study, 105 isolates of L. fermentum strains were separated from fecal samples of populations in different regions in China and their draft genomes were sequenced. Pan-genomic and phylogenetic characterizations of these strains and four model strains (L. fermentum 3872, CECT5716, IFO3956 and VRI003) were performed. Phylogenetic analysis indicated that there was no significant adaptive evolution between the genomes of L. fermentum strains and the geographical location, sex, ethnicity and age of the hosts. Three L. fermentum strains (FWXBH115, FGDLZR121, and FXJCJ61) from different branches of the phylogenetic tree and strain type L. fermentum CECT5716 were selected and their anti-inflammatory and immune modulatory activities in a dextran sulphate sodium (DSS)-induced colitis mouse model were further investigated. Both L. fermentum FXJCJ61 and CECT5716 significantly alleviated UC by reducing all colitis-associated histological indices, maintaining mucosal integrity, and stimulating replenishment of short-chain fatty acids (SCFAs), while the other two strains failed to offer similar protection. The anti-inflammatory mechanisms of L. fermentum FXJCJ61 and CECT5716 were related to the inhibition of nuclear factor kappa-B (NF-κB) signaling pathway activation and enhancement of interleukin 10 (IL-10) production. Comparative genomic analysis of these strains identified candidate genes that may contribute to the anti-inflammatory effects of specific L. fermentum strains.

Heterostructure engineering of electrocatalysts provides a fascinating platform to reasonably manipulate the physicochemical properties of nanomaterials and further improve their catalytic efficiency for water electrolysis. However, it still remains a huge challenge to construct well-designed core-shell heterostructured catalysts and identify the key role of components for synergistic catalysis. Herein, a melted polymeric salt tactics was innovatively developed to synthesize heterostructured Ni@Ni(OH)2 core-shell nanomaterials supported on porous carbon (named Ni@Ni(OH)2/PC), wherein well-defined Ni(OH)2-Ni heterostructure plays a pivotal role in improving electrocatalytic activity for water reduction and oxidation. Besides, the stable porous carbon support functions as a highway for continuous electron transfer between Ni and Ni(OH)2, and simultaneously enables the full exposure of accessible active sites. The fabricated Ni@Ni(OH)2/PC exhibits outstanding bifunctional electrocatalytic performance for overall water splitting (ƞ10 = 1.55 V) with a good long-time stability. This work sheds new light on the design of engineering heterostructure of active bifunctional electrocatalysts for efficient energy conversion system.

Lithium metal batteries are promising devices for the next-generation energy storage due to their ultrahigh theoretical specific capacity and extremely low electrochemical potential. Their inherent problem is the formation of lithium dendrites in cycling, which has induced safety concerns for almost half a century. After understanding the formation mechanism of branching structures, we propose to suppress lithium dendrites by adopting external magnetic fields to induce diffusion enhancement at the interface of the anode, thus attenuating concentration gradient there and reducing the driving force for the formation of dendritic structures. The diffusion coefficient of lithium ions is dependent on the strength of magnetic fields, confirming the effectiveness of magnetic fields in improving Li+ diffusion. After employing the magnetic field of 0.8 T, the concentration gradients at the growth front becomes nearly half of the control case, which leads to a dendrite-free lithium deposition up to the high current density of 10 mA cm−2. Both the CuLiCoO2 batteries and the symmetric LiLi coin cells show a long-term stable cycling at high current densities under the assistance of magnetic field. This diffusion enhanced technique promises a facile and general approach to suppress dendritic structures in secondary batteries, which may help to develop quick charging strategies.

The scaled-up synthesis of organic-free monolayer nanomaterials is highly desirable, especially in obtaining green energy by electrocatalysis. In this study, a method for the scaled-up synthesis of the series of monolayer layered double hydroxides (LDHs) without the addition of organic solvents is reported via the separate nucleation and aging steps process. The resulting monolayer LDHs with the thicknesses of less than 1 nm showed a narrow thickness distribution. X-ray absorption fine-structure revealed that monolayer NiFe-LDH nanosheets have a number of oxygen and metal vacancies defects. As a practical application, monolayer NiFe-LDH nanosheets containing defects showed an enhanced electrocatalytic water oxidation activity compared with that of bulk NiFe-LDH. Density functional theory calculations uncovered that excellent catalytic activity is attributed to vacancies defects. The proposed method is an economical and universally applicable strategy for the scaled-up production of monolayer LDHs.

Rational synthesis of robust layered double hydroxides (LDHs) nanosheets for high-energy supercapacitors is full of challenges. Herein, we reported an ultrasonication-assisted strategy to eco-friendly fabricate NiFe-LDHs nanosheets for the enhanced capacitive behavior. The experimental results combined with different advanced characterization tools document that the utilization of ultrasonication has a profound effect on the morphology and thickness of the as-obtained NiFe-LDHs, alternatively affecting the capacitive behavior. It shows that NiFe-LDHs nanosheets prepared with two-hour ultrasonic treatments display the exceptional capacitive performance because of the synergetic effect of ultrathin thickness, large specific surface area, and high mesoporous volume. The maximum specific capacitance of Ni3Fe1-LDHs nanosheets with the thickness of 7.39 nm and the specific surface area of 77.16 m2 g-1 reached 1923 F g-1, which is competitive with most previously reported values. In addition, the maximum specific energy of the assembled NiFe-LDHs//AC asymmetric supercapacitor achieved 49.13 Wh kg-1 at 400 W kg-1. This work provides a green technology to fabricate LDHs nanosheets, and offers deep insights for understanding the relationship between the morphology/structure and capacitive behavior of LDHs nanosheets, which is helpful for achieving high-performance LDHs-based electrode materials.

Here, we report a Ru/TS-1 catalyst for selective hydrogenolysis of guaiacol to benzene in the aqueous phase at conditions of 240 °C and 2 bar H2, achieving a benzene yield of 86% with a hydrogenolysis rate of 103.1 mmol g−1 h−1. It was found that Silicalite-1 (MFI type) with suitable pore sizes supported Ru nanoparticles (NPs) favored for hydrogenolysis of guaiacol, whereas de-aluminated Ru/HBEA, Ru/HY and Ru/MWW (without acidic sites) accelerated the parallel reactions of hydrogenation of aromatics. In addition, Ru NPs located at the orifice of Silicalite-1 was proved to be more electron-deficient and active than Ru NPs on the outer surface, as evidenced by CO-IR characterization and activity tests on Ru/Silicalite-1 (with and without templates). Moreover, Bronsted acid sites (BAS) on Ru/MFI highly promoted the hydrogenation rates of aromatics, while Lewis acid sites (LAS) on Ru/TS-1 and Ru/MFI led to a linear increase of guaiacol hydrogenolysis rate to benzene, probably due to the enhanced absorbance capability of guaiacol and phenol on the LAS of MFI. Thus, pore structure properties of MFI coupled with abundant LAS (TS-1) as well as Ru NPs on the orifice of pores of TS-1 construct a promising catalyst for achieving efficient aromatic hydrocarbons from selective hydrogenolysis of lignin.

Multi-direction impact forging (MDIF) was applied to the as-extruded ZK60 Mg alloy, and the microstructure, texture evolution and yield strength symmetry were investigated in the current study. The results showed that the average grain size of forged piece was greatly refined to 5.3 μm after 120 forging passes, which was ascribed to the segmenting effect of {10–12} twins and the subsequent multiple rounds of dynamic recrystallization (DRX). A great deal of {10–12} twins were activated at the beginning of MDIF process, which played an important role in grain refinement. With forging proceeding, continuous and discontinuous DRX were successively activated, resulting in the fully DRXed microstructure. Meanwhile, the forged piece exhibited a unique four-peak texture, and the initial //ED fiber texture component gradually evolved into multiple texture components composed of //FFD (first forging direction) and //FFD texture. The special strain path was the key to the formation of the unique four-peak texture. The {10–12} twinning and basal slip were two dominant factors to the evolution of texture during MDIF process. Grain strengthening and dislocation strengthening were two main strengthening mechanisms of the forged piece. Besides, the symmetry of yield strength was greatly improved by MDIF process.

Proper interface and band alignment always play essential roles in the separation of photoexcited charge of photocatalysts. In this work, we prepared a homodispersed S-scheme carbon nitride homojunction with local electron structure difference by a facile pre-doping and two-step calcination approach. Boron doping into heptazine created extra acceptor impurity, and Phosphorus doping into heptazine created extra donor impurity, which eventually modulated the electronic structure of carbon nitride. As heptazines with different element doping were integrated into carbon nitride by recalcination, B-CN and P-CN formed a homodispersed homojunction and thus produced a rich interface. Meanwhile, caused by Fermi energy levels equilibrium, the band bending constructed an S-scheme homojunction, which stimulated photogenerated electrons to transfer from CB of B-CN to VB of P-CN. The homodispersed S-scheme homojunction structure led to efficient suppression of recombination of photoinduced charge and retained stronger redox charge. Consequently, the photocatalytic performance was dramatically boosted to 2620 μmol g-1 from 60 μmol g-1 of pure CN in four-hour hydrogen evolution from water. This novel method for electron structure engineering helped to provide a new strategy for designing homojunction photocatalysts with excellent photocatalytic performance.

Metal–organic frameworks (MOFs) containing open metal sites are important materials for acetylene (C2H2) adsorption. However, it is inefficient or even impossible to search suitable MOFs by molecular simulation method in nearly infinite MOFs space. Therefore, machine learning (ML) methods are adopted in the material screening and prediction of high-performance MOFs. In this paper, architecture, chemical and structural features are used to analyze the C2H2 adsorption performance of the MOFs. Different ML algorithms are applied to perform classification and regression analysis to the factors affecting material adsorption. By decision tree (DT) algorithm, it is found that only PV, GSA, and Cu-OMS are sufficient to determine the high adsorption of the MOFs. Furthermore, the influence of topology on the performance of MOFs is obtained. Gradient Boosting Decision Tree (GBDT), Support Vector Machine (SVM), and Back Propagation Neural Network (BPNN), are introduced to analyze the quantitative structure–property relationship (QSPR) between C2H2 adsorption and the features of MOFs. The prediction of the GBDT model is found to have the highest accuracy, with R2 as 0.93 and RMSE as 11.58. In addition, the GBDT model is used for feature analysis, and the contribution of each feature to the performance is obtained, which is of great significance for the design and analysis of MOFs. The successful application of ML to MOFs screening greatly reduce the calculation time and provides important reference for the design and synthesis of new MOFs.

A superior carbocatalyst ultrahigh N-doped graphene (NG) was prepared by a novel self-sacrificial templating method of one-step annealing vitamin B9. The NG catalyst with pyrolysis temperature of 800 oC (abbreviated VB9-NG-800) has an ultrahigh nitrogen content of 13.5 wt.% and demonstrated the highest activity for the oxidation of bio-based alcohols and terpenes with molecular oxygen without any additives. Systematic characterizations and quantum-chemical calculations further manifested that high contents of graphitic N and pyridinic N species in VB9-NG-800 promoted the generation of •O2− active species from molecular oxygen effortlessly, resulting in excellent catalytic performance for aerobic oxidation.

This paper reports on analysis of an experimental study that aimed to determine the apparent gas permeability in cracked concrete. There is a lack of research on this topic in the international literature, due to the difficulty of performing reliable experimental testing for gas permeability. The principal interest of this work is to present new and reliable experimental results. Analytical functions between the evolution of the apparent crack permeability and the apparent crack opening are also proposed. These functions appear to be relevant in consideration of Poiseuille theory.

Twinning-detwinning (TDT) behavior in a strongly basal-textured Mg-Li alloy during two-step compression (RD)-compression (ND) process was investigated using quasi-in-situ EBSD. TDT behavior and TDT variants selection were statistically discussed with the loading path for the first time. Non-Schmid twinning behavior was observed in the first step compression, owing to the local stress fluctuations by neighboring twins; in contrast, Schmid's law well predicted the detwinning variants selection. This asymmetrical TDT behavior was first investigated to date related with the strong basal texture and loading path. Besides, with the progress of compression, Schmid factors for twinning demonstrated a decreasing tendency; however, those for detwinning during the second step displayed an abnormally increasing trend, fundamentally stemming from prior twinning behavior.

Novel hybrid coatings on pure magnesium were prepared by combining plasma electrolytic carburizing (PEC) with micro-arc oxidation (MAO) to further enhance the anti-corrosion property in this paper. Scanning electron microscopy (SEM) was used to observe the micro-structure of the coatings, meanwhile, energy dispersive spectrometry (EDS) and X-ray diffraction (XRD) were separately used to investigate the elemental as well as phase compositions of the coatings. The anti-corrosion property of the coatings was evaluated by potentiodynamic polarization curves as well as electrochemical impedance spectroscopy (EIS).The results show that PEC process is closely related with the effects of adsorption as well as diffusion of the activated carbon atoms, and it can provide a favorable pretreatment surface with predesigned chemical composition to obtain a new kind of phase, namely SiC with superior corrosion resistance and chemical stability, in the following PEC+MAO hybrid coatings. Meanwhile, PEC preprocessing also can afford an excellent micro-structure to increase the coating thickness as well as to improve the compactness of the PEC+MAO hybrid coatings. During the fabrication process of the PEC+MAO hybrid coatings, an overlapping phenomenon in regard to coating thickness can be observed instead of heaping up layer by layer. Compared with both single PEC surface modification layers as well as single MAO coatings, the PEC+MAO hybrid coatings exhibit more superior anti-corrosion property. Especially, the EIS data reveal that the PEC+MAO hybrid coatings can act as an effective protection system to provide relatively excellent long-range anti-corrosion protection. Note also that employing same MAO technique for both single MAO treatment as well as PEC+MAO combining procedure is the key to this research.

Xenon capture and Xe/Kr separation are important processes in industry. For instance, Xe/Kr separation is an indispensable step in recycle and treatment of nuclear fuel emission. Among different separation methods, selectively adsorb gas molecules using porous materials is a promising way to reduce the high energy consumption in traditional cryogenic distillation. However, many reported adsorbents still face the challenges of: i) poor separation property at low Xe/Kr concentrations; ii) insufficient retention volumes, which influence the viability of whole process. In this work, we present a stable covalent organic polymer, i.e., COP-14, showing promising potential for Xe/Kr separiton. In dynamic breakthrough experiments, COP-14 successfully separates low concentration Xe (350 ppm) and Kr (35 ppm) from target gas mixtures. Meanwhile, the xenon retention volume per gram (1700 mL g-1 at 298 K) of COP-14 in dynamics absorption process achieves 3.8 times of benchmark active carbon. The good performance of the newly devloped COP-14 mainly from its rich nitrogen sites and suitable pore size with xenon molecues. The promising results of COP-14 on Xe/Kr separation in this work provide a promising way for designing efficient Xe/Kr separation mateirals.

To explore the natural resources as sustainable precursors offers a family of green materials. The use of bio-waste precursors especially the remaining from food processing is a scalable, highly abundant, and cost-effective strategy. Exploring waste materials is highly important especially for new materials discovery in emerging energy storage technologies such as lithium sulfur batteries (LSBs). Herein, waste milk powder is carbonized and constructed as the sulfur host with the hollow micro-/mesoporous framework, and the resulting carbonized milk powder and sulfur (CMP/S) composites are employed as cathodes for LSBs. It is revealed that the hollow micro-/mesoporous CMP/S framework can not only accommodate the volume expansion but also endow smooth pathways for the fast diffusion of electrons and Li-ions, leading to both high capacity and long cycling stability. The CMP/S composite electrode with 56 wt.% loaded sulfur exhibits a remarkable initial capacity of 1596 mAh g−1 at 0.1 C, corresponding to 95% of the theoretical capacity. Even at a rate of 1 C, it maintains a high capacity of 730 mAh g−1 with a capacity retention of 72.6% after 500 cycles, demonstrating a very low capacity fading of only 0.05% per cycle. Importantly, the Coulombic efficiency is always higher than 96% during all the cycles. The only used source material is expired waste milk powders in our proposal. We believe that this “trash to treasure” approach will open up a new way for the utilization of waste material as environmentally safe and high performance electrodes for advanced LSBs.

International audience; Rational design and synthesis of low-cost trifunctional electrocatalysts with improved stability and superior electrocatalytic activity for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) are highly desirable but remain as the bottlenecks at the current state of technology. In this paper, the cobalt-iron (Co–Fe) composite supported on nitrogen-doped carbon nanotubes (CoFe composite/NCNTs) is synthesized. The intrinsic OER and HER catalytic activities of this CoFe composite/NCNTs composite are significantly improved with palladium (Pd) nanocluster decoration [Pd-coated (CoFe composite/NCNTs)]. The as-prepared Pd-coated (CoFe composite/NCNTs) catalyst exhibits excellent trifunctional electrocatalytic activity and stability due to the interfacial coupling between Pd and (CoFe composite/NCNTs). This catalyst is successfully employed in the water electrolysis cell as both OER and HER electrode catalysts, flexible rechargeable Zn-air battery as the bifunctional ORR and OER electrode catalyst. The cell voltage of this catalyst-coated electrodes requires only 1.60 V to achieve 10 mA cm−2 current density for water electrolysis cell, which is comparable to and even better than that of Pt/C and Ir/C based cell. The primary Zn-air battery using this catalyst shows a constant high open-circuit voltage (OCV) of 1.47 V and a maximum power density of 261 mW cm−2 in the flooded mode configuration. Most importantly, a flexible Zn-air battery with this catalyst runs very smoothly without a change in voltage gap during flat, bending, and twisting positions.

Solar distillation is a sustainable and promising technique to generate fresh water. However, the solar vapor generation is a high energy consumption process, resulting in a low water yield under natural sunlight. Hence, developing of advanced evaporators that can simultaneously reduce the energy requirement of water vaporization and accelerate solar water evaporation remains a great challenge. In this study, we report the fabrication of a multifunctional hydrogel of HxMoO3/PNIPAM with PNIPAM as hydratable skeleton and HxMoO3 as the light-absorbing unit for solar water evaporation. The experimental results demonstrate that the as-prepared hydrogel owns excellent photothermal activity. Accurately, the fabricated hydrogel -based solar evaporators achieved high water evaporation rate of 1.65 kg m−2 h−1 with the energy conversion efficiency of 85.87% under 1 kW m−2 irradiation. The enhanced photothermal activity of HxMoO3/PNIPAM hydrogel can be attributed to the synergistic effects of the components composed in this hierarchical architecture that change the water state and further speed up water evaporation. The HxMoO3/PNIPAM evaporators indicate its great potential for practical implementation of solar water evaporation.

Magnesium (Mg) alloys are extensively used in the automotive and aircraft industries due to their prominent properties. The selection of appropriate process parameters is an important decision to be made because of the cost reduction and quality improvement. This decision entails the selection of suitable process parameters concerning various conflicting factors, so it has to be addressed with the Multiple Criteria Decision Making (MCDM) method. Therefore, this work addresses the MCDM problem through the TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) and COPRAS (COmplex PRoportional ASsessment) methods. The assessment carried out in the material Mg AZ91 with the Solid Carbide (SC) drill bit. The dependent parameters like drilling time, burr height, burr thickness, and roughness are considered with the independent parameters like spindle speed and feed rate. Drilling alternatives are ranked using the above said two methods and the results are evaluated. The optimum combination was found on the basis of TOPSIS and COPRAS for simultaneous minimization of all the responses which is found with a spindle speed of 4540 rpm and a feed rate of 0.076 mm/rev. The identical sequencing order was observed in TOPSIS and COPRAS method. The empirical model was developed through Box-Behnken design for each response. Superior empirical model developed for drilling time which is 3.959 times accurate than the conventional equation. The trends of various dependents based on the heterogeneity of various independents are not identical, these complex mechanisms are identified and reported. The optimized results of the Desirability Function Approach are greater accordance with the TOPSIS and COPRAS top rank. The confirmation results are observed with lesser deviation suggesting the selection of the above independent parameters.

Seeking for extremely active and durable bifunctional electrocatalysts towards the overall water splitting possesses a strategic significance on the development of sustainable and clean energy for the replacement of fossil fuels. Ir-based nanomaterials are deemed as one of the most high-efficiency oxygen evolution reaction electrocatalysts while the hydrogen evolution reaction performance is unfavorable. In this work, we report a one-pot hydrothermal synthesis of N-doped graphene anchored Ir nanoparticles (Ir/N-rGO) with ultrasmall particle size (∼2.0 nm). Apart from the predictably superior OER performance, the resultant Ir/N-rGO also displays excellent hydrogen evolution reaction (HER) performance, requiring merely 76 and 260 mV overpotentials to achieve the current density of 10 mA cm-2 towards HER and OER, respectively. When applied as the bifunctional electrodes for overall water splitting, Ir/N-rGO needs a lower overpotential (1.74 V) to achieve a current density of 50 mA cm-2 in alkaline solution, exceeding that of Pt/C and RuO2 couple (1.85 V). Thus, the as-fabricated Ir/N-rGO has a commendable prospect in the practical application of alkaline water electrocatalysis.

Developing a suitable catalyst for the elimination of highly toxic carbonyl sulfide (COS) and hydrogen sulfide (H2S) is of great significance in terms of industrial safety and environmental protection. We demonstrate here the facile synthesis of graphitized 2D micro-meso-macroporous carbons by one-step carbonization of a mixture of urea and glucose at 700–900 °C. The as-synthesized graphitized catalysts, designated as 2D-NHPC-x (x = urea/glucose mass ratio), are endowed with an ultra-high concentration (12.9–20.2 wt%) of stable and versatile nitrogen sites (e.g. pyrrole and pyridine) which are anchored on the surface via stable covalent bonding. As a result, the 2D-NHPC-x are active in catalytic hydrolysis of COS on pyrrolic N to H2S, and the H2S can be subsequently captured on pyridinic N and converted to elemental sulfur at ambient conditions over the same materials. Among the prepared catalysts, 2D-NHPC-x can catalytically hydrolysize 91% of COS to H2S at 30 °C, whereas the conversion ratio over the common catalysts g-C3N4 and Fe2O3 are below 6.0%. Furthermore, these catalysts also exhibit H2S conversion and sulfur selectivity of nearly 100% at 180 °C with long-time durability, which is higher than those of the most reported carbon-based catalysts. In contrast, the H2S capacities of activated carbon, ordered mesoporous carbons (OMC) and N-doped OMC are 3.9, 1.5, and 2.39 mmol/g, respectively. Both the experimental and theoretical results are disclosed that 2D-NHPC-x are superior to the nitrogen-doped porous materials ever applied in simultaneous catalytic elimination of both COS and H2S.

Because of COVID-19, factories are facing many difficulties, such as shortage of workers and social alienation. How to improve production performance under limited labor resources is an urgent problem for global manufacturing factories. This work studies an energy-efficient job-shop scheduling problem with limited workers. Those workers can have multiskills. A many-objective model with five objectives, that is: 1) makespan; 2) total tardiness; 3) total idle time; 4) total worker cost; and 5) total energy, is built. To solve this many-objective optimization problem (MaOP), a novel fitness evaluation mechanism (FEM) based on fuzzy correlation entropy (FCE) is adopted. Two construction methods for reference points are proposed to build the bridge between MaOP and a fuzzy set. Based on FCE and cluster methods, an environmental selection mechanism (ESM) is proposed to achieve a balance between solution convergence and diversity. With the proposed FEM and ESM, two many-objective evolutionary algorithms are proposed to solve MaOP. The effect of FCE-based FEM and ESM on the performance of algorithms is verified via experiments. The proposed algorithms are compared with four well-known peers to test their performance. The extensive experimental results show that they are very competitive for the considered many-objective scheduling problem.

The laser welding (LW) process of highly reflective materials presents low thermal efficiency and poor stability. To solve the problem, the effects of subatmospheric environment on LW process, technological parameters in subatmospheric environment on weld formation and welding with sinusoidal modulation of laser power on the stability of LW process in subatmospheric environment were explored. The AZ31 magnesium (Mg) alloy was used as the test materials. The test result revealed that the weld penetration in subatmospheric environment can increase by more than ten times compared with that under normal pressure. After the keyhole depth greatly rises, significantly periodic local bulge is observed on the backwall surface of the keyhole and the position of the bulge shifts along the direction of the keyhole depth. Eventually, the hump-shaped surface morphology of the welded seam is formed; moreover, the weld width in local zones in the lower part of the welded seam remarkably grows. During LW in subatmospheric environment, the weld penetration can be further greatly increased through power modulation. Besides, power modulation can inhibit the occurrence of bulges in local zones on the backwall of the keyhole during LW in subatmospheric environment, thus further curbing the significant growth of the weld widths of hump-shaped welding beads and local zones in the lower part of welded seams. Finally, the mechanism of synchronously improving the thermal efficiency and stability of LW process of highly reflective materials through power modulation in subatmospheric environment was illustrated. This was conducted according to theoretical analysis of recoil pressure and observation results of dynamic behaviors of laser induced plasma clouds and keyholes in the molten pool through high speed photography.

Ionic liquids (ILs) have attracted increasing attention since last few decades due to their high molecular design abilities and wide applications in different fields. In this study, four novel fluorescent isoquinolino [2,1-a]quinoxalin-5-ium ILs were designed and synthesized via a two-step process including a simple dual Schiff's base formation and a subsequent [RhCp∗Cl2]2-catalyzed oxidative C–H activation/annulation reaction. The as-synthesized ILs were extensively characterized using FT-IR, 1H-NMR, 13C-NMR, 19F-NMR, HSQC-NMR, HMBC-NMR and HR-MS. Their photophysical properties were determined by steady-state fluorescence spectroscopy. The results demonstrate that all these ILs showed dual or triple emissions, large stokes shift (90 nm) and mechanochromic behaviors. Basing on solvatochromism and titration experiments, it is thought that the emission bands of the ILs are raised from their local excited states, charge transfer states or excited state proton transfer of cations, while the substitute effect of these quinoxaline derived ILs on their stokes shifts is negligible.

Using first-principles calculations, hydrogen evolution reaction (HER) activity on two-dimensional (2D) gallium chalcogenides monolayers GaX (X = O, S, Se, and Te) as well as the derived Janus monolayers Ga2XY (X≠Y, X/Y = O, S, Se, and Te) were systematically examined. It was found that Ga2OSe Janus monolayer with a 0.3% strain has the lowest ΔGH∗ of 0.19 eV (modified to −0.01 eV including the solvation effect) because (i) O is the most electronegative among X/Y atoms, (ii) the Ga2OSe monolayer has a larger lattice parameter with respect to GaO monolayer, and (iii) the built-in electric field is enhanced after H adsorption. The enhanced H adsorption with the lattice stretching is a result of the weaker Ga–O bond strength before H adsorption and the reduced electron fillings of anti-bonding molecular orbital formed by H 1s and O 2pz orbitals after H adsorption. The O-pz band center can be served as a descriptor to describe the HER activity trend for these p-block materials. Moreover, Ga2OSe monolayer has appropriate band alignment, distinguished optical absorption coefficient (105 cm−1), low exciton binding energy (0.71 eV), and the spontaneous HER process, indicating that it is a highly potential candidate for near-infrared photocatalyst for hydrogen production. Our research provides a novel paradigm that forming Janus structure can effectively tune the HER activity, which would guide the searching for excellent HER photocatalysts for clean hydrogen production.

Solvent rinse treatments using polar methanol (MeOH) and nonpolar n-hexane have been developed for controlling material concentration gradients along the longitudinal direction of non-fullerene acceptor-based bulk heterojunction (BHJ) films comprised of electron donor polymer, PBDB-T and acceptor, ITIC-m. Before the used solvents (chlorobenzene with 1 vol.% DIO) were completely evaporated, ITIC-m rich domains were formed at the top surface of the BHJ films after they were rinsed with MeOH, as evidenced by water contact angle, atomic force microscopy, time-of-flight secondary ion mass spectroscopy, which led to enhanced electron transport in the conventional structure of organic solar cells (OSCs). In contrast, after rinsing with n-hexane, ITIC-m rich domains were formed at the bottom surface of the films, which improved electron transport in the inverted structure OSCs. The enhanced carrier transports increased the PCEs (11.80% and 11.15%) in both conventional and inverted OSCs by 10.29% and 10.35% compared with control devices. The versatile control of material concentration gradients is determined to be feasible owing to the chemical interaction of the used substrates (glass, PEDOT:PSS, and ZnO) and rinsing solvents.

High-purity anhydrous magnesium chloride was prepared from magnesia and ammonium chloride. The chlorination process was analyzed and then the critical stages affecting the purity of anhydrous magnesium chloride were pinpointed. The effect of sample dimension on the above critical stages was investigated respectively. The purity guarantee mechanism of anhydrous magnesium chloride was proposed. After that, magnesium metal was obtained via electrolyzing the anhydrous magnesium chloride-containing molten salt. The new process for the continuous production of magnesium metal from magnesia was proposed and discussed. The incomplete chlorination reaction and the hydrolysis of anhydrous magnesium chloride are the two critical stages affecting the purity of the anhydrous magnesium chloride. The dimension of the sample can influence reaction process and reaction mechanism, and thus the problems of incomplete chlorination reaction and hydrolysis can be solved together. The magnesia content in anhydrous magnesium chloride was below 0.1 wt.% when the ratio of height to diameter of the sample was over 2.43. The content of impurities in the magnesium metal obtained met the specifications of the product Mg9980. The current efficiency was (94.7±1.8)% and the electricity consumption was (9107±97) kW h/t.

Herein, wooden-stick-based thermoelectric legs are introduced as a new type of thermoelectric legs. As a proof of concept, graphite- and bismuth-coated wooden sticks are fabricated with a green method, and their use as thermoelectric elements is successfully demonstrated by constructing a test thermoelectric generator. The generator based on 20 pairs of p–n legs shows a maximum power output of ∼18 nW on heating one side of the device to 70°C. The strategy can suitably be extended to other good thermoelectric materials. The approach can be promising due to the ultralow thermal conductivity of the wooden substrate pillars in contrast to other typical substrates such as glass, and hence, better thermal gradients across the device can be achieved. These environmentally friendly, non-toxic and low-cost wooden-stick-based thermoelectric devices with good thermoelectric material coatings can be conveniently used for low-grade industrial waste heat conversion applications.

The near-infrared (NIR) persistent luminescence materials (PLMs) can remain long-lasting luminescence after removal of the excitation light, which permits bioimaging with high sensitivity owing to the absence of background fluorescence interference from in situ excitation. Recently, the NIR PLMs have aroused intensive research interest in bioimaging. However, the optimal excitation wavelength of current NIR PLMs is located in the ultraviolet region with shallow tissue penetration, making it difficult to activate effectively in vivo, and seriously hindering their further application in bioimaging. Herein, we report a novel kind of Cr3+ ions and Y3+ ions co-doped NIR PLM, Zn1.3Ga1.4Sn0.3O4:Cr3+,Y3+ (ZGSCY), which emits NIR persistent luminescence at 696 nm. Compared with Zn1.3Ga1.4Sn0.3O4:Cr3+ (ZGSC) excited by the light with a wavelength in the biological window (>650 nm), after being co-doped with Y3+ ions, the NIR persistent luminescence performance of ZGSCY is significantly improved because of the increase of trap concentration in the matrix. In addition, we synthesized ZGSCY nanoparticles (NPs) by the combustion method, which exhibit excellent optical properties after being excited by the light with a wavelength in the biological window. After surface modification with PEG, the ZGSCY NPs present low cytotoxicity. Notably, due to the co-doping of Y3+ ions, the signal-to-noise ratio (SNR) of ZGSCY NPs in vivo imaging is about 1.8 times higher than that of the ZGSC NPs. Furthermore, the rechargeable in vivo imaging and passive tumor-targeted imaging are successfully achieved by activating with a light-emitting diode (LED, 659 nm) after intravenous injection of ZGSCY. Thus, this kind of NIR PLM with high excitation efficiency performance in the biological window is expected to promote its biomedical application in deep tissues.

Featuring exceptional mechanical and functional performance, MWCNTs and graphene (nano)platelets (GNPs or GnPs; each platelet below 10 ​nm in thickness) have been increasingly used for the development of polymer nanocomposites. Since MWCNTs are now cost-effective at US$30 per kg for industrial applications, this work starts by briefly reviewing the disentanglement and surface modification of MWCNTs as well as the properties of the resulting polymer nanocomposites. GNPs can be made through the thermal treatment of graphite intercalation compounds followed by ultrasonication; GNPs would have lower cost yet higher electrical conductivity over 1,400 ​S ​cm−1 than MWCNTs. Through proper surface modification and compounding techniques, both types of fillers can reinforce or toughen polymers and simultaneously add anti-static performance. A high ratio of MWCNTs to GNPs would increase the synergy for polymers. Green, solvent-free systhesis methods are desired for polymer nanocomposites. Perspectives on the limitations, current challenges and future prospects are provided Refereed/Peer-reviewed