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In the vicinity of a competing electronic order, superconductivity emerges within a superconducting dome in the phase diagram, which has been demonstrated in unconventional superconductors and transition-metal dichalcogenides (TMDs), suggesting a scenario where fluctuations or a partial melting of a parent order are essential for inducing superconductivity. Here, we present a contrary example, the two-dimensional (2D) superconductivity in transition-metal carbide can be readily turned into charge density wave (CDW) phases via dilute magnetic doping. Low temperature scanning tunneling microscopy/spectroscopy (STM/STS), transport measurements, and density functional theory (DFT) calculations were employed to investigate Cr-doped superconducting Mo2C crystals in the 2D limit. With ultralow Cr doping (2.7 atom %), the superconductivity of Mo2C is heavily suppressed. Strikingly, an incommensurate density wave (IDW) and a related partially opened gap are observed at a temperature above the superconducting regime. The wave vector of IDW agrees well with the calculated Fermi surface nesting vectors. By further increasing the Cr doping level to 9.4 atom %, a stronger IDW with a smaller periodicity and a larger partial gap appear concurrently. The resistance anomaly implies the onset of the CDW phase. Spatial-resolved and temperature-dependent spectroscopy reveals that such CDW phases exist only in a nonsuperconducting regime and could form long-range orders uniformly. The results provide the understanding for the interplay between charge ordered states and superconductivity in 2D transition-metal carbide.

Graphene doping continues to gather momentum because it enables graphene properties to be tuned, thereby affording new properties to, improve the performance of, and expand the application potential of graphene. Graphene can be chemically doped using various methods such as surface functionalization, hybrid composites (e.g., nanoparticle decoration), and substitution doping, wherein C atoms are replaced by foreign ones in the graphene lattice. Theoretical works have predicted that graphene could be substitutionally doped by aluminum (Al) atoms, which could hold promise for exciting applications, including hydrogen storage and evolution, and supercapacitors. Other theoretical predictions suggest that Al substitutionally doped graphene (AlG) could serve as a material for gas sensors and the catalytic decomposition of undesirable materials. However, fabricating Al substitutionally doped graphene has proven challenging until now. Herein, we demonstrate how controlled-flow chemical vapor deposition (CVD) implementing a simple solid precursor can yield high-quality and large-area monolayer AlG, and this synthesis is unequivocally confirmed using various characterization methods including local electron energy-loss spectroscopy (EELS). Detailed high-resolution transmission electron microscopy (HRTEM) shows numerous bonding configurations between the Al atoms and the graphene lattice, some of which are not theoretically predicted. Furthermore, the produced AlG shows a CO2 capturability superior to those of other substitutionally doped graphenes.

Background In the last decade, graphene oxide-based nanomaterials, such as graphene oxide (GO) and reduced graphene oxide (rGO), have attracted more and more attention in the field of biomedicine. Due to the versatile surface functionalization, ultra-high surface area, and excellent biocompatibility of graphene oxide-based nanomaterials, which hold better promise for potential applications than among other nanomaterials in biomedical fields including drug/gene delivery, biomolecules detection, tissue engineering, especially in cancer treatment. Results Here, we review the recent progress of graphene oxide-based multifunctional nanomaterials for cancer treatment. A comprehensive and in-depth depiction of unique property of graphene oxide-based multifunctional nanomaterials is first interpreted, with particular descriptions about the suitability for applying in cancer therapy. Afterward, recently emerging representative applications of graphene oxide-based multifunctional nanomaterials in antitumor therapy, including as an ideal carrier for drugs/genes, phototherapy, and bioimaging, are systematically summarized. Then, the biosafety of the graphene oxide-based multifunctional nanomaterials is reviewed. Conclusions Finally, the conclusions and perspectives on further advancing the graphene oxide-based multifunctional nanomaterials toward potential and versatile development for fundamental researches and nanomedicine are proposed. Graphic abstract

The development of next-generation wireless communication technology requires integrated radiofrequency devices capable of operating at frequencies greater than 90 GHz. Carbon nanotube field-effect transistors are promising for such applications, but key performance metrics, including operating frequency, at present fall below theoretical predictions. Here we report radiofrequency transistors based on high-purity carbon nanotube arrays that are fabricated using a double-dispersion sorting and binary liquid interface aligning process. The nanotube arrays exhibit a density of approximately 120 nanotubes per micrometre, a maximum carrier mobility of 1,580 cm2 V−1 s−1 and a saturation velocity of up to 3.0 × 107 cm s−1. The resulting field-effect transistors offer high d.c. performance (on-state current of 1.92 mA µm−1 and peak transconductance of 1.40 mS μm−1 at a bias of −0.9 V) for operation at millimetre-wave and terahertz frequencies. Transistors with a 50 nm gate length show current-gain and power-gain cutoff frequencies of up to 540 and 306 GHz, respectively, and radiofrequency amplifiers can exhibit a high power gain (23.2 dB) and inherent linearity (31.2 dBm output power of the third-order intercept point) in the K-band (18 GHz). Transistors based on arrays of aligned carbon nanotubes can exhibit cutoff frequencies of up to 540 GHz, and could be further scaled for operation at millimetre-wave and terahertz frequencies.

High thermal density space consumes massive energy, and cooling device accounts for large percentage of total consumption. To cut down energy consumption of cooling device, PCHP is proposed on the basis of heat pipe and evaporation technologies. Heat transfer and energy consumption models of PCHP are developed. The effects of geometric and operational parameters on the PCHP performance, including pad thickness, ambient temperature and ambient relative humidity (RH), air flow rate, are investigated. The results show that cooling capacity increases with the increase of pad thickness and airflow rate, and it decreases with the increase of ambient temperature and RH. With the increase of thickness, energy efficiency ratio (EER) increases at the start and then decreases under RH20%-40%, while it decreases continuously under RH70%-90%. EER increases with the decrease of ambient temperature, ambient RH and air flow rate. PCHP markedly enhances annual free cooling time compared with conventional heat pipe system (CHP), and the maximal enhanced free cooling time and increasing percentage occur at Urumchi and Guangzhou Cities, respectively.

The morphological and structural optimizations of electrode materials are efficient ways to enhance their electrochemical performance. Herein, we report a facile co-precipitation and subsequent calcination method to fabricate Li1.2Mn0.54Ni0.13Co0.13O2 nanosheets consisting of interconnected primary nanoparticles and open holes through the full thickness. By comparing the nanosheets and the agglomerated nanoparticles, the effects of the morphology and structure on the electrochemical performance are investigated. Specifically, the nanosheets exhibit a discharge capacity of 210 mA h g−1 at 0.5C with a capacity retention of 85% after 100 cycles. The improved electrochemical performance could be attributed to their morphological and structural improvements, which may facilitate sufficient electrolyte contacts, short diffusion paths and good structural integrity during the charge/discharge process. This work provides a feasible approach to fabricate lithium-rich layered oxide cathode materials with 2D morphology and porous structure, and reveals the relationships between their morphology, structure and electrochemical performance.

Li-Rich layered oxide microspheres are considered as one of the most attractive architectures for energy storage in batteries due to their high tapped densities and good cycling stabilities. However, the synthesis of Li-rich layered oxide microspheres derived from metal oxalate microspheres as a template still remains a challenge. Here, Li1.2Mn0.54Ni0.13Co0.13O2 microspheres assembled by orthogonally arranged nanoplates are synthesized by a simple co-precipitation method followed by a calcination process using metal oxalate microspheres as the template. The amount of H2C2O4·2H2O in the co-precipitation reaction is found to distinctly affect the final structure of the products. When used as a cathode material for lithium ion batteries, the microspheres achieve a discharge capacity of 228 mA h g−1 at 0.5C with a capacity retention of 87% after 100 cycles. These results can originate from the porous structure of the microspheres, which may not only ensure fast electrolyte accessibility and enlarge the exposed surface area, but also enhance the structural stability.

Lithium-rich layered oxides are attractive candidates of high-energy-density cathode materials for high-performance lithium ion batteries because of their high specific capacity and low cost. Nevertheless, their unsatisfactory rate capability and poor cycling stability have strongly hindered commercial applications in lithium ion batteries, mainly due to the ineffectiveness of the complicated synthesis techniques to control their morphologies and sizes. In this work, the Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials with a one-dimensional rod-like morphology were synthesized via a facile co-precipitation route followed by a post-calcination treatment. By reasonably adding NH3·H2O in the co-precipitation reaction, the sizes of the metal oxalate precursors could be rationally varied. The electrochemical measurements displayed that the Li1.2Mn0.54Ni0.13Co0.13O2 short rods delivered a high capacity of 286 mA h g−1 at 0.1C and excellent capacity retention of 85% after 100 cycles, which could be contributed to the improvement of the electrolyte contact, Li+ diffusion, and structural stability of the one-dimension porous structure.

Silicon-based complementary metal-oxide-semiconductor (CMOS) has been the mainstream logic style for modern digital integrated circuits (ICs) for decades but will meet its performance limits soon. Extensive investigations have thus been carried out using other semiconductors, especially those with extremely high carrier mobility. However, these materials usually have small or even zero band gap, which leads inevitably to large leakage current or voltage loss in ICs based on these semiconductors. In this work, we propose and demonstrate a strengthened CMOS (SCMOS) logic style using modified field-effect transistors (FETs) to solve this problem, that is, to achieve high performance, utilizing the high carrier mobility in these materials, and to reduce the current leakage resulting from their small band gap. Conventional CMOS FETs are modified to have an asymmetric structure where an additional assistant gate is introduced near the drain to further lower the potential barrier in on-state and to increase the barrier in off-state. SCMOS ICs are constructed using these modified asymmetric CMOS FETs, which demonstrate perfect rail-to-rail output with negligible voltage loss and 3 orders of magnitude suppression of the static power consumption and an operating speed similar to or even higher than that of CMOS ICs. Here, SCMOS is demonstrated using carbon nanotubes, but, in principle, this logic style can be used in ICs based on any small-band-gap semiconductors to provide simultaneously high performance and low power consumption.

We adopt Langevin dynamics to explore the stress-structure relationship of telechelic reversible associating polymer gel during startup shear flow, with shear strengths varying from Wi = 12.6 to Wi = 12640. At weak shear flow Wi = 12.6, the shear stress proportionally increases with shear strain at short times, followed by a strain hardening behavior and then passes through a maximum (σmax, γmax) and finally decreases until it reaches the steady state. During the evolution of stress, the gel network is only slightly broken and essentially maintains its framework, and the strain hardening behavior originates from the excessive stretching of chains. On the other hand, the stress-strain curve at intermediate shear flow Wi = 505.6 shows two differences from that at Wi = 12.6, namely, the absence of strain hardening and a dramatic increase of stress at large strains, which is caused by the rupture of gel network at small strains and the network recovery at large strains, respectively. Finally, at very strong shear flow Wi = 6319.7, the gel network is immediately broken by shear flow and the stress-strain curve exhibits similar behaviors to those of classical polymeric liquids.

Carbon nanotube (CNT) field-effect transistor (FET)-based biosensors have shown great potential for ultrasensitive biomarker detection, but challenges remain, which include unsatisfactory sensitivity, difficulty in stable functionalization, incompatibility with scalable fabrication, and nonuniform performance. Here, we describe ultrasensitive, label-free, and stable FET biosensors built on polymer-sorted high-purity semiconducting CNT films with wafer-scale fabrication and high uniformity. With a floating gate (FG) structure using an ultrathin Y2O3 high-κ dielectric layer, the CNT FET biosensors show amplified response and improved sensitivity compared with those sensors without Y2O3, which is attributed to the chemical gate-coupling effect dominating the sensor response. The CNT FG-FETs are modified to selectively detect specific disease biomarkers, namely, DNA sequences and microvesicles, with theoretical record detection limits as low as 60 aM and 6 particles/mL, respectively. Furthermore, the biosensors exhibit highly uniform performance over the 4 in. wafer as well as superior bias stress stability. The FG CNT FET biosensors could be extended as a universal biosensor platform for the ultrasensitive detection of multiple biological molecules and applied in highly integrated and multiplexed all CNT-FET-based sensor architectures.

Aligning dense carbon nanotube arrays Although semiconducting carbon nanotubes (CNTs) are promising candidates to replace silicon in transistors at extremely small dimensions, their purity, density, and alignment must be improved. Liu et al. combined a multiple dispersion sorting process, which improves purity, and a dimension-limited self-alignment process to produce well-aligned CNT arrays on a 10-centimeter silicon wafer. The density is sufficiently high (100 to 200 CNTs per micrometer) that large-scale integrated circuits could be fabricated. With ionic liquid gating, the performance metrics exceeded those of conventional silicon transistors with similar dimensions. Science , this issue p. 850

Compared to van der Waals two-dimensional (2D) layers with lateral covalent bonds, metallic bonding systems favor close-packed structures, and thus, free-standing 2D metals have remained, for the most part, elusive. However, a number of theoretical studies suggest a number of metals can exist as 2D materials and a few early experiments support this notion. Here we demonstrate free-standing single-atom-thick crystalline chromium (Cr) suspended membranes using aberration-corrected transmission electron microscopy and image simulations. Density functional theory studies confirm the 2D Cr membranes have an antiferromagnetic ground state making them highly attractive for spintronic applications. Moreover, the work also helps consolidate the existence of a new family of 2D metal layers.

CdTe and related II–VI compound semiconductors have been widely utilized in the field of optoelectronic devices, detectors, solar cells and so on. As the surface treatment on the wafer involved in the device fabrication process has an important impact on its subsequent photoelectric performance, the investigations on the change in structures and properties of the wafer after different surface treatments, especially the formation of new phases at the surface, have important theoretical significance and practical application value. In this work, the surface morphology and microstructure of CdTe single crystal wafers after different chemical etching processes were investigated by atomic force microscopy (AFM), Raman spectroscopy and transmission electron microscopy (TEM). With the increase of etching time to 10 min, the surface gradually became smoother with a significantly reduced surface roughness from 61.4 nm to 30.5 nm. In addition, the I–V curves of Au/CdTe contact structure illustrate the optimized ohmic contact characteristics after chemical etching with the surface leakage current increasing from 4.723 × 10−10 A to 3.640 × 10−9 A when the etching time extends up to 10 min. TEM analysis on the chemical etched surface of CdTe confirms the formation of Cd2Te2O7 phase with two variants. The d-spacing of (100)CTO and twice that of {111}CdTe being similar is the main reason for the existence of low lattice mismatch and formation of coherent interface between Cd2Te2O7 and CdTe. Furthermore, the chemical etching process is also confirmed to remove the surface damage caused by mechanical polishing effectively by comparing the interface microstructures of Au/CdTe contacts without and after 10 min of chemical etching. The formation mechanism of Cd2Te2O7 and the structure model of Au/CdTe interface are also proposed based on the TEM results.

The heat induced self-welding of nanomaterials is an important method for the artificial design and synthesis of heterogeneous composite materials. The connection and growth of solid-state crystalline nanomaterials under heat treatment normally follow the oriented attachment growth mechanism. However, there is a lack of systematic research on the interface crystallography under such formation conditions, especially for crystals with relatively large structure differences. In this work, hydrothermally grown TiO2 (B) (TB) nanofibers are chosen as examples to investigate the welded interface structure and crystallography between the same and different TiO2 polymorphs. Through the manipulation of calcination temperature, TB–TB and TB–anatase (TA) self-welded nanofiber pairs can be firstly obtained. The transmission electron microscopy (TEM) results suggest that two TB nanofibers with the same {100} single crystal form (SCF) can be connected with the same orientation or by being rotated along the fiber growth direction for certain angles. In addition, the TB nanofibers with different SCFs can also be welded through the extension and growth of (010)TB. For TB–TA self-welded pairs, the welding direction is confirmed along the long axis direction of the fiber, which is different from that of TB–TB self-welded pairs. Moreover, it is proved that the TB nanofibers with both SCFs can be welded with TA, leading to the formation of two different interfaces with typical orientation relationships. Furthermore, fewer dislocations can be found in the welded pairs with the {100} SCF of TB, which is due to the similar distribution of the voids between TiO6 octahedra for TB and TA with the orientation relationships of [010]TB//[010]TA, [100]TB//[100]TA and [106]TB//[001]TA. For the self-welded cases between TA nanofibers, the mutual rotation along different axes followed by the attachment growth was considered to be the mechanism of different interface formations. The results of this work can provide useful experimental support for the controlled synthesis of heat induced self-welded metal-oxide nanofibers.

Herein, a synergistic strategy to construct hierarchical NiMoO4@Co3V2O8 (denoted as NMO@CVO) hybrid nanorod/nanosphere clusters is proposed for the first time, where Co3V2O8 nanospheres (denoted as CVO) have been uniformly immobilized on the surface of the NiMoO4 nanorods (denoted as NMO) via a facile two-step hydrothermal method. Due to the surface recombination effect between NMO and CVO, the as-prepared NMO@CVO effectively avoids the aggregation of CVO nanosphere clusters. The unique hybrid architecture can make the most of the large interfacial area and abundant active sites for storing charge, which is greatly beneficial for the rapid diffusion of electrolyte ions and fast electron transport. The optimized NMO@CVO-8 composite nanostructure displays battery-like behavior with a maximum specific capacity of 357 C g−1, excellent rate capability (77.8% retention with the current density increasing by 10 times) and remarkable cycling stability. In addition, an aqueous asymmetric energy storage device is assembled based on the NMO@CVO-8 hybrid nanorod/nanosphere clusters and activated carbon. The device shows an ultrahigh energy density of 48.5 W h kg−1 at a power density of 839.1 W kg−1, good rate capability (20.9 W h kg−1 even at 7833.7 W kg−1) and excellent cycling stability (83.5% capacitance retention after 5000 cycles). More notably, two charged devices in series can light up a red light-emitting diode (LED) for 20 min, demonstrating its potential in future energy storage applications. This work indicates that the hierarchical NiMoO4@Co3V2O8-8 hybrid nanorod/nanosphere clusters are promising energy storage materials for future practical applications and also provides a rational strategy for fabricating novel nanostructured materials for high-performance energy storage.

Porous Ni electrodes with different textures have been fabricated by a facile electro-deposition method. The additives ammonium chloride (NH4Cl) and ammonium sulfate ((NH4)2SO4) in supporting electrolytes play a vital role in the texture of porous electrodes. Porous Ni electrodes prepared with the NH4Cl additive present a (111) plane preferred orientation. However, with the additive (NH4)2SO4, as its concentration increases, the preferred orientation changes from the (111) plane to the (200) plane. In addition, we studied the texture of the porous Ni electrodes and their influence on the hydrogen evolution reaction (HER) and sodium borohydride (NaBH4) electrooxidation. Porous Ni electrodes with the (111) preferential orientation promote the electrooxidation of NaBH4. Meanwhile, optimum catalytic activity can be obtained when both the (111) and (220) planes are preferentially oriented. In contrast, porous Ni electrodes with the (200) preferential orientation facilitate NaBH4 hydrolysis. Interestingly, the porous Ni electrode with both the (200) and (220) preferential orientations exhibits the best HER catalytic activity. This work provides new insights into the relationship between the texture and the electrocatalytic properties of porous Ni electrodes, which is desirable to design nickel electrodes more reasonably for HER or sodium borohydride electrooxidation.

Traveling magnetic field (TMF) is a potential method to control the melt flow and impurity transport during the directional solidification (DS) of silicon ingots. We numerically study the control mechanism of a downward and an upward TMF with different frequencies on the silicon melt flow and oxygen distribution in the DS process. Model experiment of generation and measurement of a TMF is first carried out to validate the magnetic field computing program. Then, the TMF frequency is varied to study its influence on the direction and magnitude of Lorentz force, pattern and intensity of silicon melt flow, and distribution of oxygen impurity. Results show that the downward TMF with large frequency can induce local melt flow above the melt-crystal interface and block the oxygen transport from the dominant flow to the interface. The upward TMF with small frequency and large amplitude can induce thoroughly upward melt flow along the crucible side wall and take the oxygen far away from the melt-crystal interface, which is better for reducing the oxygen content in the silicon melt and ingots.

Corrosion product formed on zinc sample during 2 weeks immersion in saline solution has been investigated. The corrosion layer morphology as well as its chemical composition, was analyzed using scanning electron microscopy (SEM), x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Electrochemical measurement was used to analyze the corrosion behavior. Zinc oxide, zinc hydroxide and zinc hydroxide chloride were formed on zinc surface in saline solution. The thickness of corrosion layer increased with the time increased. The pure Zn has an estimated corrosion rate of 0.063 mm y−1 after immersion for 336 h. Probable mechanisms of zinc corrosion products formation are presented., Graphical abstract Image 1, Highlights • Pure Zn displayed uniform corrosion in saline solution fluid for up to 2 weeks immersion. • Corrosion products are mainly consisted of Zinc oxide, zinc hydroxide and zinc hydroxide chloride. • The corrosion rate of pure Zn was about 0.063 mm y−1. • A corrosion mechanism of Zn in saline solution was proposed.

In recent years, two‐dimensional (2D) materials have attracted a lot of research interest as they exhibit several fascinating properties. However, outside of 2D materials derived from van der Waals layered bulk materials only a few other such materials are realized, and it remains difficult to confirm their 2D freestanding structure. Despite that, many metals are predicted to exist as 2D systems. In this review, the authors summarize the recent progress made in the synthesis and characterization of these 2D metals, so called metallenes, and their oxide forms, metallene oxides as free standing 2D structures formed in situ through the use of transmission electron microscopy (TEM) and scanning TEM (STEM) to synthesize these materials. Two primary approaches for forming freestanding monoatomic metallic membranes are identified. In the first, graphene pores as a means to suspend the metallene or metallene oxide and in the second, electron‐beam sputtering for the selective etching of metal alloys or thick complex initial materials is employed to obtain freestanding single‐atom‐thick 2D metal. The data show a growing number of 2D metals/metallenes and 2D metal/ metallene oxides having been confirmed and point to a bright future for further discoveries of these 2D materials., In this review, the authors summarize the recent progress made in the synthesis and characterization of these 2D metals, so called 2D metals/metallenes, and their oxide forms, 2D metals/metallene oxides as free standing 2D structures formed in situ through the use of TEM and STEM to synthesize these materials.

A small bandgap and light carrier effective mass (m0) lead to obvious ambipolar transport behavior in carbon nanotube (CNT) field-effect transistors (FETs), including a high off-state current and severe degradation of the subthreshold swing (SS) with increasing drain bias voltage. We demonstrate a drain-engineered method to cope with this common problem in CNT-film FETs with a sub-µm channel length, i.e., suppressing the ambipolar behavior while maintaining high on-state performance by adopting a feedback gate (FBG) structure to extend the drain region from the CNT/metal contact to the proximate CNT channels to suppress the tunneling current. Sub-400-nm-channel-length FETs with a FBG structure statistically present a high on/off ratio of up to 104 and a sub-200 mV/dec SS under a high drain bias of up to −2 V while maintaining a high on-state current of 0.2 mA/µm or a peak transconductance of 0.2 mS/µm. By lowering the supply voltage to 1.5 V, FBG CNT-film FETs can meet the requirement of standard-performance ultra large scale integrated circuits (ULSICs). Therefore, the introduction of the drain engineering structure enables applications of CNT-film-based FETs in ULSICs and could also be widely extended to other small-bandgap semiconductor-based FETs for an improvement in their off-state property.

Stretching polymer in fluid flow is a vital process for studying and utilizing the physical properties of these molecules, such as DNA linearization in nanofluidic channels. We studied the role of hydrodynamic interactions (HIs) in stretching a free star polymer in Poiseuille flow through a tube using mesoscale hydrodynamic simulations. As increasing the flow strength, star polymers migrate toward the centerline of tube due to HIs, whereas toward the tube wall in the absence of HIs. By analyzing the end monomer distribution and the perturbed flow around the star polymer, we found that the polymer acts like a shield against the flow, leading to additional hydrodynamic drag forces that compress the arm chains in the front of the star center toward the tube axis and lift the arm chains at the back toward the tube wall. The balanced hydrodynamic forces freeze the polymer into a trumpet structure, where the arm chains maintain a steady strongly stretched state at high flow strength. In contrast, the polymer displays remarkably large conformational change when switching off HIs. Our simulation results explained the coupling between HIs and the structure of star polymers in Poiseuille flow.

In this work, black multi-crystal silicon (Mc-Si) solar cells with bowl-like nanotextured surfaces were successfully fabricated by a metal-assisted chemical etching (MACE) method. Defect removal etching processes of various durations were used to form bowl-like nanostructures of three sizes on the wafer surface. Overall, a low depth and large diameter of bowl-like structure in nanotextured surfaces is demonstrated to be helpful in reducing surface recombination and improving the cell and module performance. The average cell module power of the bowl-like nanotextured surfaces with an average bowl diameter 680 nm is clearly higher by 1.51 W, 1.46 W, and 1.26 W than for nanotextured surfaces with bowl diameter 460 nm in the 18.8%, 18.9%, and 19.0% efficiency bins. A maximum cell efficiency of 19.17% and module power of 279.74 W were obtained using our MACE process in an industrial mass production line. The techniques presented in this paper can be used for the mass production of diamond wire sawing Mc-Si solar cells and meet the requirements of high efficiency and low cost in the photovoltaic industry.

Electronic interaction at metal/support interfaces could change the electronic structure and catalytic activity of a metal. Herein, Cu nanoparticles (NPs) with sizes of ˜5 nm were uniformly deposited on two-dimensional titanium carbide MXene (Ti3C2). Some electrons transferred from Cu to Ti3C2 upon hybridization as evidenced by XPS analysis and DFT calculations. The work function (5.78 eV) of Ti3C2 was higher than that (4.63 eV) of Cu NPs, which was responsible for the interfacial charge transfer. Upon formation of Cu/Ti3C2, the d-band center (ed) of Cu was shifted upwards from −2.38 eV to −2.27 eV with reference to Fermi energy. The calculated hydrogen adsorption energy (−2.57 eV) of Cu/Ti3C2 was higher than that (−2.45 eV) of unsupported Cu NPs. Such favorable hydrogen adsorption of Cu/Ti3C2 increased the number of surface-adsorbed hydrogen atoms, beneficial for the hydrogen-involved redox from the viewpoint of kinetics. Cu/Ti3C2 showed a promising catalytic activity for the reduction of 4-nitrophenol into 4-aminophenol with a normalized rate constant of 43.1 min−1 mg−1, which was 6.3 times as high as that of Cu NPs. Such enhanced catalysis was ascribed to the favorable hydrogen adsorption and good hydrophilicity of the nanohybrid. This work presents an example that the catalytic activity of Ti3C2 MXene-supported metals can be promoted by their hydrogen adsorption, which will broaden the application of other 2D MXene materials in catalysis.

The spent SCR catalyst as the hazardous waste would seriously affect the ecological environment and human life. In this study, a new method of spent SCR catalyst harmless treatment was proposed by blending the spent SCR catalyst with coal for combustion. The combustion characteristics of coal blending with spent SCR catalyst, melting solidification characteristics of V/As in spent catalyst, and leaching characteristics of V/As in bottom ash were explored by TG, ICP-MS, XRD, SEM analysis. The results show that the proper amount of spent catalyst blending with coal could promote coal combustion by reducing the ignition and burnout temperature of coal particles due to the catalytic effects of TiO2. The co-combustion of spent SCR catalyst with coal could well solidify the V/As in the bottom ash. In this process, the solidification rate of V decreased but the solidification rate of As increased with the increasing of temperature. Both of V and As solidification rate decreased with the increasing of spent catalyst blending ratios. The leaching concentration and leaching rate of V and As in the bottom ash were lower than the emission standards. The leaching concentration of As and V of the bottom ash significantly decreased due to melting of bottom ash when the temperature reached to 1300 °C. When the blending ration of catalyst blending amount increased, the leaching concentration and leaching rate of V and As increased slightly due to the decreasing of the relative amount of CaO in bottom ash, which played an important roles in the solidification of V and As.

High pressure has been demonstrated to be a powerful approach of producing novel condensed-matter states, particularly in tuning the superconducting transition temperature (Tc) of the superconducti...

Materials can exhibit exotic properties when they approach the two-dimensional (2D) limit. Because of promising applications in catalysis and energy storage, 2D transition-metal carbides (TMCs) have attracted considerable attention in recent years. Among these TMCs, ultrathin crystalline α-Mo2C flakes have been fabricated by chemical vapor deposition on Cu/Mo bilayer foils, and their 2D superconducting property was revealed by transport measurements. Herein, we studied the ultrathin α-Mo2C flakes by atomic-resolved scanning tunneling microscopy/spectroscopy (STM/S). Strain-related structural modulation and the coexistence of different layer-stacking modes are observed on the Mo-terminated surface of α-Mo2C flakes as well as various lattice defects. Furthermore, an enhanced superconductivity with shorter correlation length was observed by STS technique, and such superconductivity is very robust despite the appearance of the defects. A mechanism of superconducting enhancement is proposed based on the strain-induced strong coupling and the increased disordering originated from lattice defects. Our results provide a comprehensive understanding of the correlations between atomic structure, defects, and enhanced superconductivity of this emerging 2D material.

The presence of SO3 severely affects not only the safe and economic operation of coal-fired power plants but also the atmospheric environment. The purpose of this study was to investigate the generation of SO3 over V2O5-WO3/TiO2 catalysts. The SO3 generated during the reaction was collected by the controlled condensation method. N2 adsorption, X-ray fluorescence (XRF), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), SO2 temperature-programmed desorption (SO2-TPD), and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments were performed to evaluate the catalyst properties. The experimental results show that the generation of SO3 on the catalyst is complicated and can be promoted by NO and NH3. The generation rate of SO3 increased from 0.5 vol% to 3.29 vol% with an increase in the NO concentration from 0 to 1000 ppm. When 500 ppm NH3 was added to an atmosphere containing 500 ppm NO, the generation rate of SO3 increased from 2.23 vol% to 4.23 vol%. The addition of NH3 led to a significant reduction in the specific surface area of the catalyst due to the generation of ammonium bisulfate (ABS). In addition, the results show that the proportion of lattice oxygen (Oα) and the adsorption of SO2 on the catalyst would be promoted by NO and NH3, and DRIFTS experiments further proved that NO and NH3 promoted the generation and transformation of the intermediate products VOSO4 and HSO4−.

Hollow microspheres fabricated from nanoparticles are considered as one of the most attractive architectures for energy storage devices owing to their high tap density, short Li+ diffusion length, and good cycling stability. It is, however, difficult to fully assess the effectiveness of controlling the parameters of hollow microspheres, such as their structure and size. This is due to the adverse effects of the applied treatments, especially in the case of lithium-based microspheres used for energy storage. In the present study, LiMnPO4 hollow microspheres with evolvable structures (hollow, urchin-like, and yolk-shell architectures) and tuneable sizes (600 nm, 1.5 μm, and 3 μm) were synthesised via a facile solvothermal process using precipitated Li3PO4 hollow microspheres as the sacrificial templates. A possible formation mechanism is proposed in this paper based on observations from time-dependent experiments. The process parameters such as the additive ((NH4)2SO4), diethylene glycol (DEG)-to-H2O volume ratio of the solvent, and Li3PO4 template size were found to distinctly impact the final phase, structure, and size of the products. Compared with the 3-μm urchin-like and 600-nm hollow microspheres, the 3-μm hollow microspheres exhibited excellent electrochemical properties including a high rate capability and good cycling stability, which can be attributed to the synergy between the nano-size of the subunits and the stable structure of the microspheres.

In this work, porous Cu-doped V2O5·nH2O thin film electrodes have been directly synthesized via low-temperature annealing and simple drop-casting method from V2O5/H2O2 sol with various concentration copper ion (Cu2+). It is interesting to find that the mass fraction of Cu2+ has effects on the morphologies, valence state of vanadium, and electrochemical performance of Cu-doped V2O5·nH2O thin film. When the mass fraction of Cu2+ is 1 wt.%, the obtained Cu-doped V2O5·nH2O thin film electrode shows network porous nanostructure. Moreover, it still shows high discharge specific capacity of 344 mAh g−1 at a current density of 250 mA g−1. Excellent cycling stability with only 0.14% per cycle degradation during 104 cycles can be obtained even at a high current density of 550 mA g−1. Improvement of electrochemical performance is attributed to unique network porous nanostructure, accelerating the lithium-ion transfer rate in the de-intercalation or intercalation process.

The understanding of the generation mechanism of SO3 on V/W/Ti catalysts provides needed information for the achievement of ultra-low emission of pollutants and effective control of SO3 generation. This study predominantly investigates the catalytic oxidation mechanism of V/W/Ti catalysts for SO3 generation under H2O and CO2 conditions. Ion Chromatography (IC), X-ray Fluorescence (XRF), Brunauer–Emmett–Teller (BET) specific surface area, Scanning Electron Microscopy image (SEM), Energy Dispersive X-ray (EDX), SO2 Temperature-Programmed Desorption (SO2-TPD), X-ray Photoelectron Spectroscopy (XPS) experiments, and Fourier Transform Infrared spectroscopy (FT-IR) were used to characterize catalyst properties and the catalytic oxidation generation mechanism of SO3. Results show that Catalyst V content was more influential than physical property on the generation of SO3. In this study, when H2O or CO2 was added into the reaction atmosphere, the generation amount of SO3 would increase firstly, and then gradually decrease with the further increase of H2O or CO2 concentration. Through further mechanistic analysis, it was found that the influence mechanism of H2O and CO2 on the generation of SO3 was different. Various kinds of intermediate species such as [OH] and HOSO2 were introduced by the addition of H2O, resulting in the increase of lattice oxygen (Oα) proportion and SO3 generation path. However, the inhibition effects of high concentration of H2O on SO2 adsorption and sulfur oxides migration were the main reason for the decrease of SO3 generation under high H2O containing conditions. Conversely, although the adsorption SO2 was promoted by CO2, high CO2 addition leads to the apparently reduction of Oα proportion on catalyst resulting in the decrease of SO3 generation.

An Eulerian–Eulerian model coupled with a population balance model (PBM) is adopted to investigate the growth process of polysilicon particles in a polysilicon fluidized bed reactor. A novel partic...

The edge-defined film-fed growth (EFG) is a promising method to grow large β-Ga2O3 crystal. The thermal field in the EFG system should be designed to provide proper conditions for growing large-size and high-quality crystals. 2D calculation of the meniscus shape and 3D global simulations are carried out to investigate and design the thermal fields in an EFG system for the growth of β-Ga2O3 ribbon crystals. Effects of the induction coil position on the thermal field before seeding are firstly studied. Results indicate that it is difficult to improve all features of the thermal field just by changing the coil position. An improved design of adding a crucible cover is then proposed and investigated. It turns out that the crucible cover is a feasible design to improve the thermal field for the EFG growth of β-Ga2O3 ribbon crystals comprehensively. The studies are expected to provide essential knowledge for further design and optimization of the EFG system.

Invar alloys are widely used in the aerospace, but their manufacturability and mechanical properties are not well understood when they are employed in additive manufacturing. The laser melting deposition (LMD) technology is utilized to the surface repair of Invar alloys. In this work, the microstructure evolution, quantitive subgrain size, as well as the subgrain orientation are investigated using optical microscopy. Moreover, the effect of partially remelting of successive layers is exhibited. It is explicit that the cellular crystal orientation is strongly influenced by the heat flow which is subject to the scanning direction. Considering to the basic laws of Invar alloy microstructure evolution during LMD process, the relations between heat input and produced subgrain characteristics are further elucidated. The results show that a slight increase of λ from 4.4 μm to 5.2 μm at the function of heat input varied from 98.6 J/mm2 to 114 J/mm2. Moreover, it was notable that a reverse change in the dimension discrepancy of remelted and non-remelted subgrains occurred with two kinds of heat input.

Bi2WO6 photocatalyst has attracted much interest but suffers from easy recombination of electron-hole pairs. Herein carbon dots (CDs) as a cocatalyst were hydrothermally hybridized with Bi2WO6 nanoplates with aim of efficient separation of charge carriers. Electron transfer from CDs to Bi2WO6 across their interfaces upon contact was revealed by XPS results and further supported by differential charge density analyses. Such electron transfer led to a built-in electric field pointing from CDs to Bi2WO6, which drove photoinduced electrons flowing to CDs under light irradiation. DFT simulation showed the introduced electron was mainly distributed on CDs instead of Bi2WO6, which implied that CDs had impressive capability of taking photoinduced electrons under irradiation. Such efficient charge separation was experimentally supported by photoelectrochemical analyses. The superoxide radicals and holes were found to participate in the photodegradation of RhB under visible light irradiation. The enhanced photocatalytic activity of CDs/Bi2WO6 could be ascribed to the efficient charge separation and large specific area of Bi2WO6 nanoplates.

An LiMnPO4 cathode with an active crystal orientation can contribute towards its charge transfer kinetics. However, the development of a facile strategy for the manipulation of its active crystal orientation remains a great challenge. Here, we reported a simple solvothermal method to prepare LiMnPO4 hollow microspheres assembled by radially aligned nanoplates with the (010)-exposed surface and thin [010] thickness. The amount of the NH4H2PO4 additive was the key factor that controlled the ac-plane surface area of the assembled subunits of the microspheres. When applied for the cathode, the nanoplate-assembled microspheres exhibited superior rate capability compared to those of the nanoprism-assembled and thick plate-assembled microspheres, showing the discharge capacities of ∼130 mA h g−1 at 1 C and ∼81 mA h g−1 at 10 C. The improved electrochemical performance could be attributed to the advantages of the large (010) surface and the thin [010] thickness of the assembled nanoplates, which may facilitate easy access to the surface and rapid migration of lithium ions.

Composite solder alloys reinforced by different nominal concentrations of α-Fe2O3 nanoparticles are examined and the performance of corresponding copper (Cu) pillar bumps during thermal cycling (TC) tests is investigated. Firstly, the spherical α- Fe2O3 nanoparticles (50 nm in diameter) were successfully prepared by a chemical method. Then, the Sn-xFe2O3 composite solders with different concentrations of α-Fe2O3 were deposited on the surface of Cu pillar bumps by electroplating. During electroplating, the concentration of α-Fe2O3 nanoparticles in the plating solution ranged from 0 g/L to 0.04 g/L. TC tests of fabricated joints were conducted from − 65°C to 150°C for different numbers of cycles. The microstructure, evolution of interfacial intermetallic compounds (IMCs) and the shear strength of the solder joints were investigated following TC tests. Cross-sectional analysis indicates that adding α-Fe2O3 nanoparticles can remarkably suppress the overgrowth of the interfacial IMCs. Compared to the strength of joint without nanoparticles after the TC test, the strength of joints increases with the addition of α-Fe2O3 and an optimum nominal concentration of 0.032 g/L in the electroplating solution was identified.

Reducing toxic Cr(VI) to Cr(III) by formic acid attracts much interest for chromium remediation but still needs efficient catalysts to boost its sluggish kinetics. Herein, PdCu nanoalloy (∼3 nm) was uniformly immobilized in N-doped carbon/graphene (NCG) porous nanosheets that were derived from the sandwich-like ZIF-8/graphene oxide precursor. The resulting PdCu/NCG showed a high specific area (SBET) of 656.1 m2 g−1 and a superior activity (kn) of 38.2 min−1 mg−1 for the Cr(VI) reduction with formic acid as reductant, which outperformed its monometallic counterparts and most of noble-metal catalysts. The catalytic performance highly depended on the composition of PdCu nanoalloy and NCG support. DFT calculation and XPS analysis proved the presence of electron transfer from Cu to Pd upon alloying, which induced an upshift of d-band center (ed) of PdCu metals with respect to Fermi energy. The elevated ed facilitated the chemisorption and C–H breakage of formic acid to produce active H species on the catalyst. Such alloying-induced electronic modification of PdCu alloy and porous feature of NCG nanosheets both accounted for the catalytic enhancement.

Zinc was recently suggested to be a potential candidate material for degradable coronary artery stent. The corrosion behavior of pure zinc exposed to r-SBF up to 336 h was investigated by electrochemical measurements and immersion tests. The morphology and chemical composites of the corrosion products were investigated by scanning electron microscope, grazing-incidence X-ray diffraction, X-ray photoelectron spectroscopy and Fourier transform infrared spectrometer. The results demonstrate that the initial corrosion products on the pure zinc mainly consist of zinc oxide/hydroxide and zinc/calcium phosphate compounds. The pure Zn encounters uniform corrosion with an estimated corrosion rate of 0.02–0.07 mm y−1 during the immersion, which suggests the suitability of pure Zn for biomedical applications.

Acetylene black (AB) was exfoliated and functionalized through a single-pot method then be assembled to a novel porous carbon material by utilizing sulfur as both template and sulfur source. The defect-rich structures of the obtained AB play a critical role in providing more appropriate sites for sulfur atom doping. After a pyrolysis process in the presence of melamine as N doping agent, the sulfur template was decomposed and yielded the N,S-codoped porous carbon material with additional porosity. The synergistic effects between the defect-projecting and heteroatoms-doping boost the activity of electrocatalysts in terms of the enhanced oxygen reduction efficiency and optimized kinetic process, both are better than that of commercial Pt/C. And the improved reactivity between carbon atoms and heteroatoms as well as sulfur and nitrogen atoms greatly suppress the loss of active ingredient of the catalyst, the mechanism yields a striking long-term stability for the unique metal-free OAB@S-N electrocatalyst.

The continuous-feeding Czochralski method is a cost-effective method to grow single silicon crystals. An inner crucible is used to prevent the un-melted silicon feedstock from transferring to the melt-crystal interface in this method. A series of global simulations were carried out to investigate the impact of the inner crucible on the oxygen impurity distributions at the melt-crystal interface. The results indicate that, the inner crucible plays a more important role in affecting the O concentration at the melt-crystal interface than the outer crucible. It can prevent the oxygen impurities from being transported from the outer crucible wall effectively. Meanwhile, it also introduces as a new source of oxygen impurity in the melt, likely resulting in a high oxygen concentration zone under the melt-crystal interface. We proposed to enlarge the inner crucible diameter so that the oxygen concentration at the melt-crystal interface can be controlled at low levels.

In this study, in situ transmission electron microscopy is performed to study the interaction between single (monomer) and paired (dimer) Sn atoms at graphene edges. The results reveal that a single Sn atom can catalyze both the growth and etching of graphene by the addition and removal of C atoms respectively. Additionally, the frequencies of the energetically favorable configurations of an Sn atom at a graphene edge, calculated using density functional theory calculations, are compared with experimental observations and are found to be in good agreement. The remarkable dynamic processes of binary atoms (dimers) are also investigated and is the first such study to the best of the knowledge. Dimer diffusion along the graphene edges depends on the graphene edge termination. Atom pairs (dimers) involving an armchair configuration tend to diffuse with a synchronized shuffling (step-wise shift) action, while dimer diffusion at zigzag edge terminations show a strong propensity to collapse the dimer with each atom diffusing in opposite directions (monomer formation). Moreover, the data reveals the role of C feedstock availability on the choice a single Sn atom makes in terms of graphene growth or etching. This study advances the understanding single atom catalytic activity at graphene edges. Web of Science art. no. 2104340

Zinc (Zn) and its alloys have received increasing attention as new alternative biodegradable metals. However, consensus has not been reached on the corrosion behaviour of Zn. As cardiovascular artery stent material, Zn is supposed to contact with plasma that contains inorganic salts and organic components. Protein is one of the most important constitute in the plasma and could adsorb on the material surface. In this paper, bovine serum albumin (BSA) was used as a typical protein. Influences of BSA on pure Zn corrosion in phosphate buffered saline is investigated as a function of BSA concentrations and immersion durations by electrochemical techniques and surface analysis. Results showed that pure Zn corrosion was progressively accelerated with BSA concentrations (ranging from 0.05 to 5 g L−1) at 0.5 h. With time evolves, formation of phosphates as corrosion product was delayed by BSA adsorption, especially at concentration of 2 g L−1. Within 48 h, the corrosion of pure Zn was alleviated by BSA at concentration of 0.1 g L−1, whereas the corrosion was enhanced after 168 h. Addition of 2 g L−1 BSA has opposite influence on the pure Zn corrosion. Furthermore, schematic corrosion behaviour at protein/Zn interfaces was proposed. This work encourages us to think more about the influence of protein on the material corrosion and helps us to better understand the corrosion behaviour of pure Zn.

Loess&ndash, mudstone/soil-rock interfacial landslide is one of the prominent landslide hazards that occurs in soil rock contacting zones. It is necessary to develop sensors with high sensitivity to weak and low frequency vibrations for the early warning of such interfacial landslides. In this paper, a novel monitoring sensor prototype with enhanced and adaptive sensitivity is developed for this purpose. The novelty of the sensitive sensor is based on the variable capacitances and negative stiffness mechanism due to the electric filed forces on the vibrating plate. Owing to the feedback control of adjustable electrostatic field by an embedded micro controller, the sensor has adaptive amplification characteristics with high sensitivity to weak and low frequency input and low sensitivity to high input. The design and manufacture of the proposed sensor prototype by Micro-Electro-Mechanical Systems (MEMS) with proper packaging are introduced. Post-signal processing is also presented. Some preliminary testing of the prototype and experimental monitoring of sand interfacial slide which mimics soil&ndash, rock interfacial landslide were performed to demonstrate the performance of the developed sensor prototype with adaptive amplification and enhanced sensitivity.

In this study, the laser cladding system with an IPG YLS-6000 fiber laser was used, and the WC–Ti6Al4V powder reinforced composite coatings on Ti6Al4V titanium alloy with various bionic structures were innovatively fabricated. The microstructures and surface damage behavior of the coatings were characterized by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. Additionally, the wear resistance of different bionic structures was evaluated, which had not been comprehensively explored in the published literature. The results indicated that the un-melted WC particles in the coatings act as a hard reinforcement, avoiding serious wear of the coating. In addition, the hard coatings exhibit excellent deformation resistance and the soft substrate cushion the shear stress. So when the “Ratio”, which refers to the laser cladding area to sample area, is between 0.25 and 0.3, the sample has the highest wear resistance. Furthermore, the “Dot + Line” bionic structure has the best wear resistance compared with other structures. The separated line units and the addition of dot units can improve the stress concentration state of bionic structure are conducive to release the stress to the substrate under the cladding layer.

Monolithic optoelectronic integration based on a single material is a major pursuit in the fields of nanophotonics and nanoelectronics in order to meet the requirements of future fiber-optic telecommunication systems and on-chip optical interconnection systems. However, the incompatibility between silicon-based electronics and germanium or compound semiconductor-based photonics makes it very challenging to realize optoelectronic integration based on a single material. Here, the integration between silicon waveguides and a carbon nanotube (CNT) optoelectronic system is demonstrated. Waveguide-integrated photodetectors based on the CNT exhibit 12.5 mA/W photoresponsivity at 1530 nm, which presents an improvement of 97.6 times enhanced absorption efficiency compared to that without the waveguide. Multiplied output signals of cascading photodetectors are used to control the output of CNT-based logic gates, thereby demonstrating that the CNT-based optoelectronic integration system is compatible with silicon photonics. Our work indicates that carbon nanotubes have the potential for future integration between nanophotonics and nanoelectronics on a single chip.

Summary A fully coupled multicomponent flow and geomechanics model, which incorporates viscous flow, Kundsen diffusion, molecular diffusion, multi-component adsorption/desorption and geomechanics effect, is developed to study the enhanced gas recovery and CO2 storage in fractured shale reservoirs. Specifically, an efficient hybrid model, which consists of single porosity model, multiple porosity model and Embedded Discrete Fracture Model (EDFM), is adopted to model multiscale fractures. In flow equations, the Peng-Robinson EOS, extended Langmuir isotherm and Fick’s Law are adopted. In geomechanical portion, the proppant nonlinear deformation is considered. Then, the mixed space discretization (i.e., finite volume method for flow and stabilized XFEM for geomechanics) and modified fixed stress sequential implicit methods are applied to solve the proposed model. The robustness of the proposed method is demonstrated through several numerical examples, and a comprehensive analysis of the mechanisms for enhanced gas recovery and CO2 storage in fractured shale gas reservoirs is carried out, which takes into account Kundsen diffusion, molecular diffusion, multi-component adsorption/desorption, proppant nonlinear deformation, and different injection strategies including huff-n-puff scenario. Results show that CO2 injection is an effective approach for enhancing shale gas recovery, and the injected CO2 can be stored as free, adsorbed, and dissolved state. Besides, we can also find that stimulated reservoir volume, natural/induced fractures, hydraulic fractures, various transport/storage mechanisms and injection strategies have significant effects on enhanced gas recovery and CO2 storage in fractured shale reservoirs.