Efficient spatial separation of charge carriers over Sv-ZnIn2S4/NH2-MIL-88B(Fe) S-scheme heterojunctions for enhanced photocatalytic H2 evolution and antibiotics removal performance.

The exploration of highly efficient sunlight-assisted photocatalyst for photodegradation of organic contaminants or energy conversion is strongly encouraged. In this work, we designed a novel three-dimensional spindle-like Sv-ZIS@NMFe heterojunction made of amino functionalized NH2-MIL-88B(Fe) (NMFe) and ZnIn2S4 nanosheets with abundant sulfur vacancies (Sv-ZIS). The structural properties of NMFe materials, such as a clearly defined system of pores and cavities, were retained by the Sv-ZIS@NMFe composites. Additionally, the incorporation of sulfur vacancies, -NH2 functional groups, and well-matched energy level positions led to various synergistic effects that considerably enhanced internal electron transformation and migration, as well as improved adsorption performance. Consequently, under visible light irradiation, the optimized sample exhibited superior hydrogen production activity and tetracycline hydrochloride photodegradation performance. At last, density functional theory calculations was used to further elucidated the possible photoreactivity mechanism. This study demonstrates that the Sv-ZIS@NMFe heterojunction materials formed by ZnIn2S4 with suitable sulfur vacancies and amino functionalized Fe-MOFs have promising applications in photocatalysis.

Effect of ZrC on the Microstructure and Properties of CrMnFeCoNi High-Entropy Alloy Coatings Prepared by a Plasma Transferred Arc Process.

The low strength caused by the single FCC structure of the CrMnFeCoNi high entropy alloy (HEA) limits its application in the field of coating. Here, we prepared high-entropy alloy coatings of CrMnFeCoNi with different ZrC contents on Q235 steel by a plasma transferred arc process. The effects of ZrC on the microstructure and properties of the CrMnFeCoNi HEA coating were investigated by optical microscopy, scanning electron microscope, and X-ray diffraction and by employing a potensiostat/galvanostat. The results showed that ZrC mainly existed in the coatings as a second phase, having little influence on the main crystal structure and micromorphology of the CrMnFeCoNi HEA coating. The hardness of the CrMnFeCoNi HEA coating increased with the ZrC content. ZrC can effectively improve the corrosion resistance of the CrMnFeCoNi HEA coating. In a 1 mol/L NaCl solution with 4 wt% ZrC, the annual corrosion rate was only 5.997% of that of the HEA coating. Nevertheless, the improvement in the wear resistance of CrMnFeCoNi high-entropy alloy coatings was not apparent with the addition of ZrC. Consequently, the addition of ZrC to the FeCoCrNiMn high-entropy alloy coating holds promise for applications in corrosion resistance, particularly in oceanic environments.

A Special Ancient Bronze Sword and Its Possible Manufacturing Technique from Materials Science Analysis.

In this study, it was found that an ancient bronze sword had special microstructures, i.e., a tin (Sn)-rich layer (Sn: 38.51 wt.%), that was around 0.1-0.3 mm in thickness in the bronze substrate (Sn: 18.57 wt.%). This sword was unearthed from the same Chu tombs of the "Sword of Gou Jian", and dated back to the late Spring and Autumn Period (496 BC-464 BC). The experimental and theoretical analyses revealed that (1) the Sn-rich layer exhibited higher microhardness (around 650 HV) than the sword body (around 300 HV); (2) the Sn-rich layer showed a brittle fracture due to the formation of a large amount of α + δ eutectoid, while the sword body was of good toughness due to a large amount of α-Cu solid solution phase; and (3) theoretical calculations of Sn diffusion in the Cu substrate indicated that this Sn-rich layer could have been formed within several hours or several days if the temperature was above 600 °C. Therefore, this sword was proposed to be a novel kind of composite bronze sword, and the possible manufacturing technique was a surface treatment called "dip or wipe tinning" or tin amalgam, which was widely used in the Bronze Age. Technically, this process possesses more advantages than the well-known two-times casting for making the "double-colour" or bi-metallic composite bronze sword. This research showed that the materials processing level was beyond our expectations for ancient China 2500 years ago.

Ultra-stretchable, super-hydrophobic and high-conductive composite for wearable strain sensors with high sensitivity.

With continuous development of artificial intelligence technology, strain sensors have attracted widespread attention. In this work, a novel high-performance wearable strain sensor is prepared by using a kind of ultra-stretchable, super-hydrophobic and high-conductive composite. The preparation process is as follows, i.e., using common elastic band (EB) as the polymer matrix, nano carbon black (CB) and carbon nanotubes (CNTs) as mixed conductive filler, and then modified by polydimethylsiloxane (PDMS) to obtain the PDMS/(CB + CNTs)/EB composite for assembling assemble flexible wearable strain sensors. Experimental results reveal the following excellent properties: 1) The composite exhibits excellent mechanical properties and super-hydrophobicity, i.e., the tensile strength is up to 996.5%, and the elastic modulus and tensile strength increase 49.2% and 59.2%, compared with pristine EB; 2) The composite strain sensor exhibits high sensitivity (the gauge factor reaches up to 648.83 under strain range of 979.9-996.5%), and it still shows stable performance after 3000 cycles tests (100% strain); 3) It is a well candidate to be used for monitoring human body motions including large and subtle body movements; 4) The composite sensor also has advantages of easy access of raw materials, simple preparation, easy mass production and relatively low production cost, showing a broad application prospect in wearable electronic products.

Construction of Direct Z-Scheme Heterojunction NiFe-Layered Double Hydroxide (LDH)/Zn0.5Cd0.5S for Photocatalytic H2 Evolution.

It is of great significance to construct heterojunctions using industrially produced co-catalysts. The direct Z-scheme composite photocatalyst provides an effective separation of photogenerated carriers. Herein, a kind of novel 2D/3D direct Z-scheme NiFe-LDH/Zn0.5Cd0.5S is prepared. Compared with fresh catalysts, the NiFe-layered double hydroxide (LDH)/Zn0.5Cd0.5S composite exhibits advantages including excellent visible light response ability and photoelectric performance and improved H2 evolution rate by 11.6 times. Combining with theoretical calculations, ESR, XPS, and experimental results, the direct Z-scheme mechanism of the photocatalytic reaction is proposed. There is a channel for electron transfer between Zn0.5Cd0.5S and NiFe-LDH, and the electrons of Zn0.5Cd0.5S directly combine with the valence band holes of NiFe-LDH. Finally, the electrons remaining on NiFe-LDH can reduce H+ to generate H2. This process effectively achieves separation of photogenerated carriers and increases photocatalytic H2 evolution.

One-Step Construction of Multi-Walled CNTs Loaded with Alpha-Fe2O3 Nanoparticles for Efficient Photocatalytic Properties.

The aggregation and the rapid restructuring of the photoinduced electron-hole pairs restructuring in the process of photoelectric response remains a great challenge. In this study, a kind of Multi-walled carbon nanotubes loaded Alpha-Fe2O3 (CNTs/α-Fe2O3) heterostructure composite is successfully prepared via the one-step method. Due to the synergistic effect in the as-prepared CNTs/α-Fe2O3, the defect sites and oxygen-containing functional groups of CNTs can dramatically improve the interface charge separation efficiency and prevent the aggregation of α-Fe2O3. The improved photocurrent and enhanced hole-electron separation rate in the CNTs/α-Fe2O3 is obtained, and the narrower band gap is measured to be 2.8 ev with intensive visible-light absorption performance. Thus, the CNTs/α-Fe2O3 composite serves as an excellent visible light photocatalyst and exhibits an outstanding photocatalytic activity for the cationic dye degradation of rhodamine B (RhB). This research supplies a fresh application area forα-Fe2O3 photocatalyst and initiates a new approach for design of high efficiency photocatalytic materials.

Graphene-Reinforced Zn-Ni Alloy Composite Coating on Iron Substrates by Pulsed Reverse Electrodeposition and Its High Corrosion Resistance.

In this paper, a novel kind of graphene (Gr)-reinforced Zn-Ni alloy composite coating is successfully prepared on an iron substrate by pulsed reverse electrodeposition. Hydrophilic graphene oxide (GO) is directly added to the electrolyte and reduced to Gr during coating. The experimental results reveal that (1) there is an optimal adding amount (about 0.4 g/L) of GO in the electrolyte for achieving the highest mechanical properties and corrosion resistance; (2) the composite coating shows grain refinement and a dense microstructure due to heterogeneous nucleation sites provided from the Gr sheets during electrodeposition; and (3) compared to the regular Zn-Ni coating, the composite coating exhibits many enhancements, including hardness increase by 2.3 times, elastic modulus increase by 39%, and corrosion rate decrease from 37.66 to 1.30 mils/annum. This process has advantages such as being simple, effective, well repeatable, economical, and supporting large-scale production and is expected to be widely applied in electronics, automobiles, marine engineering, and military industries.

Correction: The potential role of borophene as a radiosensitizer in boron neutron capture therapy (BNCT) and particle therapy (PT).

Correction for 'The potential role of borophene as a radiosensitizer in boron neutron capture therapy (BNCT) and particle therapy (PT)' by Pengyuan Qi et al., Biomater. Sci., 2020, 8, 2778-2785, DOI: .

Scalable Production of Boron Quantum Dots for Broadband Ultrafast Nonlinear Optical Performance.

A simple and effective approach based on the liquid phase exfoliation (LPE) method has been put forward for synthesizing boron quantum dots (BQDs). By adjusting the interactions between bulk boron and various solvents, the average diameter of produced BQDs is about 7 nm. The nonlinear absorption (NLA) responses of as-prepared BQDs have been systematically studied at 515 nm and 1030 nm. Experimental results prove that BQDs possess broadband saturable absorption (SA) and good third-order nonlinear optical susceptibility, which are comparable to graphene. The fast relaxation time and slow relaxation time of BQDs at 515 nm and 1030 nm are about 0.394-5.34 ps and 4.45-115 ps, respectively. The significant ultrafast nonlinear optical properties can be used in optical devices. Here, we successfully demonstrate all-optical diode application based on BQDs/ReS2 tandem structure. The findings are essential for understanding the nonlinear optical properties in BQDs and open a new pathway for their applications in optical devices.

Hierarchical porous "skin/skeleton"-like MXene/biomass derived carbon fibers heterostructure for self-supporting, flexible all solid-state supercapacitors.

Two-dimensional transition metal carbide and nitride are promising energy storage materials. However, the aggregation and rearrangement of two-dimensional nanosheets limit their electrochemical performance. In this paper, a novel hierarchical porous "skin/skeleton"-like MXene/biomass derived carbon fibers (MXene/CF) heterostructure is prepared by one-step pyrolysis, which efficiently weakens the stacking of MXene nanosheets. Moreover, MXene/CF has a well-defined hierarchical porous structure, thereby facilitating electrolyte penetration and providing efficient and stable channels for rapid diffusion/transfer of ions to the electrode and producing functional MXene-based electrodes. When MXene/CF heterostructure is applied as a self-supporting electrode for supercapacitors, the electrode has high volumetric capacitance of 7.14 F cm-3, good rate characteristics (63.9% from 0.5 to 100 A g-1), and excellent cyclic stability (99.8% after 5000 cycles). In addition, all solid-state symmetric supercapacitors based on MXene/CF electrodes are also assembled, which not only exhibits high capacitance and rate performance, but also has good flexibility and long durability. The device still maintains structural integrity and steady capacitance even after 2500 cycles at different bending angles. This work is expecting to guide the design of the next generation of flexible, portable and highly integrated supercapacitors with high capacity and rate performance to further meet the requirements of sustainable development.

"One-Step" Carbonization Activation of Garlic Seeds for Honeycomb-like Hierarchical Porous Carbon and Its High Supercapacitor Properties.

In this paper, a simple "one-step" route is introduced to prepare a kind of novel honeycomb-like hierarchical porous carbon (h-HPC) by carbonizing and activating garlic seeds. Due to its special microstructure, h-HPC shows excellent electrochemical properties and high supercapacitor performances. The experimental results reveal the following: (1) There exists an optimal condition for synthesizing h-HPC, i.e., 700 °C carbonization temperature and 1:1 mass ratio of KOH and garlic seeds. (2) h-HPC has a three-dimensional interconnected porous structure and exhibits a specific surface area as high as 1417 m2/g with a narrow pore size distribution. (3) When h-HPC is employed as an electrode material in supercapacitors, its specific capacitance reaches a value up to 268 F/g at a current density of 0.5 A/g and excellent rate capability. (4) The h-HPC-based symmetric supercapacitor shows a high energy density of 31.7 Wh/kg at a power density of 500 W/kg and retains 99.2% of the initial capacitance after 10,000 charge/discharge cycles at 200 mV/s. When compared with similar works, these data are competitive, which demonstrates that the garlic-derived h-HPC is a kind of promising electrode material for the next-generation high-energy-density supercapacitors.

MXene/N-Doped Carbon Foam with Three-Dimensional Hollow Neuron-like Architecture for Freestanding, Highly Compressible All Solid-State Supercapacitors.

Currently, the MXene-based flexible supercapacitors have caused much attention due to their excellent mechanical performance and novel electrical property. However, the aggregation and rearrangement of MXene nanosheets in the process of electrode preparation limit their electrochemical performance. Herein, a kind of novel MXene/N-doped carbon foam (MXene/NCF) compressible composite with three-dimensional (3D) hollow interconnected neuron-like architecture is directly prepared by one-step pyrolysis and used for the freestanding, highly compressible supercapacitors. The synergistic effect exists in the MXene/NCF composite when applied to supercapacitors: NCF can provide the additional pseudocapacitance by N atom doping and simultaneously supports the MXene nanosheets to construct the 3D hollow interconnected neuron-like architecture for supplying highly stable, efficient channels for ion diffusion/electron transport and more contact sites, and that the MXene enhances conductivity and hydrophilicity. Therefore, the freestanding MXene/NCF electrode shows a remarkable gravimetric capacitance of 332 F g-1 and volumetric capacitance of 3162 mF cm-3, superior rate performance of 64% (from 0.5 to 100 A g-1), and 99.2% capacity retention after 10,000 cycles. Significantly, the MXene/NCF-based all solid-state supercapacitors still show a high specific capacitance and a large rate performance. In addition, the device can be compressed arbitrarily under 60% strain with almost no change in morphology and electrochemical property. These excellent properties expect that the MXene/NCF composite has broad applications in the field of flexible supercapacitors.

The potential role of borophene as a radiosensitizer in boron neutron capture therapy (BNCT) and particle therapy (PT).

The potential role of borophene as a radiosensitizer in PT and BNCT was investigated. Our study focused on two aspects: (1) the synthesis and characterization of borophene nanomaterials; and (2) biocompatibility and dose enhancement. To overcome the limitation of vapor-based technology, we successfully deployed the liquid-phase exfoliation (LPE) method to produce borophene targeting for biomedical applications. Bringing together spatial distribution and dose deposition, the in vitro microdosimetry study was carried out in the presence of borophene. A quantitative study of the dose enhancement ratio (DER) was performed with Monte-Carlo simulation. The synthesized borophene showed good biocompatibility with less than 10% cell death at a concentration of up to 0.2 mg ml-1. The uptake of borophene within individual cells penetrated through cell membranes but outside the nucleus. For proton PT, no significant change in the DER is found. For carbon PT, the DER increases by about 5% as the concentration of 10B reaches 1 mg g-1. For BNCT, a DER of more than 2 can be obtained for a concentration as low as 100 µg g-1. This study lays a foundation for utilizing novel borophene-based nanomaterials as radiosensitizers as well as imaging probes in cancer treatment.

A Wrinkled Ag/CNTs-PDMS Composite Film for a High-Performance Flexible Sensor and Its Applications in Human-Body Single Monitoring.

In this paper, a flexible Ag/CNTs-PDMS (polydimethylsi-loxane) composite film sensor based on the novel design philosophy was prepared. Its force-electric effect mechanism is based on the generation of micro-cracks in the Ag film during external forcing, leading to resistance variation. Experimental results find that Ag film thickness has a strong influence on the sensor's sensitivity, which exhibits a tendency of first increasing and then decreasing the Ag film thickness, and also has an optimal thickness of 4.9 µm for the maximum sensitivity around 30. The sensitive mechanism can be theoretically explained by using the quantum tunneling effect. Due to the use of the wrinkled carbon nanotubes (CNTs) film, this sensor has advantages, such as high sensitivity, large strain range, good stability and durability, cheap price, and suitability for large-scale production. Preliminary applications on human-body monitoring reveal that the sensor can detect weak tremors and breathe depth and rate, and the corresponding heartbeat response. It provides possibilities to diagnose early Parkinson's disease and exploit an early warning system for sudden infant death syndrome and sleep apnea in adults. In addition, as a force-electric effect sensor, it is expected to have broad application areas, such as a man-machine cooperation, and a robotic system.

Flexible photodetectors based on reticulated SWNT/perovskite quantum dot heterostructures with ultrahigh durability.

Recently, single-walled carbon nanotube (SWNT) films have been regarded as a promising channel material for flexible photodetectors due to their high intrinsic carrier mobility, conductivity, and mechanical flexibility. However, the application of SWNTs in photonic devices is limited due to their weak light absorption and the absence of a gain mechanism. Here, we demonstrate a high-performance flexible photodetector that consists of a reticulated SWNT film covered with a thin film of CsPbI3 perovskite colloidal quantum dots. The unique hierarchical reticulated structure of the SWNTs provides such films with extremely high tensile strength and great extensibility, which can ensure the appropriate toughness for achieving flexible photodetectors. Meanwhile, the perovskite quantum dots enhance light absorption, thereby sensitizing the creation of free electrical carriers within the SWNTs. This hybrid photodetector exhibits an extended photonic response and gain compared with the original pure SWNT devices. In addition, the device exhibits good robustness against repetitive bending and stretching, suggesting its applicability as a large-area wearable flexible photodetector.

TiO2/graphene/CuSbS2 mixed-dimensional array with high-performance photoelectrochemical properties.

The growing demands for reproducible and clean sources of power has prompted the exploitation of novel materials for solar-energy conversion; in any case, the improvement of their conversion efficiency remains a big challenge. We report a mixed-dimensional heterostructure to synchronously enhance charge separation and light-absorption of the photoanodes via the introduction of two-dimensional reduced graphene oxide and zero-dimensional CuSbS2 quantum dots on one-dimensional TiO2 arrays. The experimental results show that the graphene sheets with a low Fermi level and a superior electron mobility accept photo-excited electrons from TiO2 and enable fast electron transportation; while the CuSbS2 quantum dots promote the visible light-absorption of the photoanode. The synergistic effects in this mixed-dimensional (1D-2D-0D) heterostructure photoanode induce a markedly raised photoconversion efficiency of 1.2% at 0.3 V and a photocurrent density of 5.5 mA cm-2 at 0.4 V. Furthermore, the photocurrent density of the mixed-dimensional heterostructure exceeds previously reported TiO2-based photoanodes in neutral media. The improved photoelectrochemical properties are attributed to the synergistic-effect-induced highly organized, mixed-dimensional architectures. It is expected that the mixed-dimensional heterostructure photoanode will be a potential candidate for applications in environmental remediation and energy fields.

Functionalized Graphene for Mechanical Property Enhancement of Polymer Composites.

Because of its high strength and high toughness, graphene has been widely used in mechanical reinforced composites. In general, the mechanical enhancement depends mainly on the properties of graphene itself and the number of surface chemical functional groups attached on it. In this paper, we report a method to improve the mechanical performance of polymer by using a kind of functionalized reduced graphene oxide (F-RGO), i.e., the F-RGO is prepared by chemical treatment, and then the F-RGO/polyvinylidene fluoride (PVDF) composite films are obtained by spin coating. Because the chemical treatment can increase the number of functional groups on the surface and edge of F-RGO, these functional groups make the F-RGO sheets strongly coupled with PVDF molecules, so as to achieve the purpose of mechanical enhancement. The experimental results reveal that the mechanical properties of the F-RGO/PVDF composite films are improved for 42% times, when comparing with regular RGO/PVDF composite films.

Preparation of high-concentration substitutional carbon-doped TiO2 film via a two-step method for high-performance photocatalysis.

In this paper, we present a facile two-step method for preparing a high-concentration substitutional carbon-doped TiO2 (TiO2-x C x ) film. First, the titanium substrate undergoes gas carburizing, followed by micro-arc oxidation (MAO) to form a carbon-doped TiO2 film on the surface. The process can be described as direct oxidation of titanium carbide (O→TiC x ). The experimental results reveal that compared with traditional thermal annealing, this process could increase the carbon doping concentration to 6.07 at% and x to 0.24 in TiO2-x C x . The TiO2-x C x film exhibits a significant red-shift in the band-gap transition, a narrow band gap of 2.77 eV, and excellent photocatalytic performance, more than two times higher than that of undoped TiO2 film. This method is simple, efficient, economical, environmentally friendly, and adapts to mass production. This experimental strategy can also be used in preparing other doped elements.

Synthesis and enhanced microwave absorption properties: a strongly hydrogenated TiO2 nanomaterial.

Due to its improved physical and chemical performances, a strongly hydrogenated TiO2 was designed and produced successfully by using a sealing-transfer reduction method at a relatively low temperature (425 °C). The microstructures, electromagnetic and microwave absorbing properties were investigated in detail. Experimental results revealed that: (1) the minimum reflection loss (RL) value of the hydrogenated TiO2 up to -53.8 dB (99.999 99% of EM wave attenuation) was reached at 11.2 GHz, and the RL values below -20 dB (99%) were obtained in a frequency range of 7.3-16.8 GHz. (2) Compared to pristine TiO2 and black TiO2 in other reports, the present hydrogenated TiO2 exhibited greatly improved microwave absorption performance. Moreover, the mechanism was also discussed. It was demonstrated that the excellent microwave absorption performance of the black TiO2 arose from the strong dielectric loss, excellent impedance matching and attention loss due to associated relaxation and interfacial polarization. It is expected that the hydrogenated TiO2 exhibits great potential applications in the area of high performance microwave absorbing materials. In addition, it is believed that the black TiO2 @ magnetic metals composites will display an excellent microwave absorbing property.

Present Perspectives of Advanced Characterization Techniques in TiO2-Based Photocatalysts.

TiO2 is the most investigated photocatalyst because of its nontoxicity, low cost, chemical stability, and strong photooxidative ability. Because of the morphology- and structure-dependent photocatalytic properties of TiO2, accurate characterization of the crystal and electronic structures of TiO2-based materials and their performance during the photocatalytic process is crucial not only for understanding the photocatalytic mechanism but also for providing experimental guidelines as well as a theoretical framework for the synthesis of high performance photocatalysts. In this review, we focused on the advanced characterization techniques that are utilized in the studies on the TiO2 structures and photocatalytic performance of TiO2 and TiO2-based materials. It is therefore anticipated that this review can provide a novel perspective to understand the fundamental aspects of photocatalysis and inspire the development of new photocatalysts with superior performances.