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ZrB2 is widely used in refractory linings and electrodes as well as in a range of applications including microelectronics and cutting tools, owing to its excellent characteristics, such as high hardness, high melting point, high strength, high thermal conductivity, and good thermal shock resistance. However, ZrB2 readily oxidizes, especially at high temperatures, which is ascribed to the reaction between ZrB2 and O2 in air. This study shows that a structural self-deterioration phenomenon occurs in ZrB2, even in vacuum or inert atmosphere. ZrB2 exhibits a characteristic, irreversible increase in resistivity in a high vacuum–high temperature environment. During repeated variable temperature resistivity testing, the resistivity of ZrB2 increases by 3.28% in the first cycle and 0.61% in the second. To investigate further, in-situ TEM showed that ZrB2 experiences an unusual phase transition reaction at high temperatures, even under a high vacuum environment. Oxidation results in a large number of disordered, layered structures and holes inside the ZrB2 particles. This microstructure evolution mechanism decreases the electrical conductivity and affects the performance of ZrB2. The study demonstrates the need to thoroughly investigate the microstructure changes in ZrB2 at high temperatures, under an inert atmosphere or high vacuum, and to widen the investigations to other properties beyond electrical resistivity.

The sensitivity of ethanol sensor is of paramount importance in a variety of areas, including chemical production with ethanol, alcohol testing for driving safety, etc. Herein, α-Fe2O3 nano-cylinders with atomic carbon layers are synthesized, for the first time, through in-situ catalytic chemical vapor deposition combined with hydrothermal techniques for the detection of ethanol. The reported α-Fe2O3@C nano-cylinders with double surficial strain effects deliver an ethanol detection sensitivity of ～8 times as compared with α-Fe2O3 nano-cylinders, ∼10 times higher as compared with its detection sensitivity to ammonia, para-xylene, methanol and benzene. The sensor also exhibits over-14-day operation stability and the minimum detection limit of 10 ppm. To our best knowledge, the performances surpass those of previously reported α-Fe2O3. Such attractive performances are attributed to the enhanced charge transfer in α-Fe2O3 owing to the double surficial strain effects of α-Fe2O3@C nano-cylinders and the efficient adsorption of ethanol with atomic carbon layers.

Chemical stability of phosphors is critical to the efficiency and lifetime of the white light-emitting diodes. Therefore, many strategies have been adopted to improve the stability of phosphors. However, it is still lack of report on the improvement of thermal stability and hydrolysis resistance of phosphors by a single layer coating. Due to the high transmittance and high chemical inertness of graphene, it was coated on the surface of Sr2Si5N8:Eu2+ phosphor by chemical vapor deposition, aiming to improve its thermal stability and hydrolysis resistance. The chemical composition and microstructure of the coating were characterized and analyzed. A nanoscale carbon layer was attached on the surface of Sr2Si5N8:Eu2+ phosphor particles in an amorphous state. In coated Sr2Si5N8:Eu2+ phosphor, the oxidation degree of Eu2+ to Eu3+ was significantly suppressed. At the same time, the surface of Sr2Si5N8:Eu2+ particle turned from hydrophilic to hydrophobic after carbon coating, and consequently the hydrolysis resistance of Sr2Si5N8:Eu2+ phosphor was greatly improved. After tests at 85 °C and 85% humidity for 200 h, the carbon coated Sr2Si5N8:Eu2+ phosphor still maintained about 95% of its initial luminous intensity as compared with 35% of the uncoated. By observing the in-situ microstructure evolution of coated phosphor in air-water vapor environment, remained presence of the carbon layer even at 500 °C explained the excellent chemical stability of carbon coated Sr2Si5N8:Eu2+ phosphor in complex environment. These results indicate that a nanoscale carbon layer can be used to provide superior thermal stability and hydrolysis resistance of (oxy) nitrides phosphors.

As the most common energy storage technology on the market, lithium-ion batteries are widely used in various industries and have a profound impact on our daily lives, with the characteristics of high voltage, high capacity, good safety performance, and long cycle life. Lithium metal was first used in the anode of lithium-ion batteries. However, the inherent growth of lithium dendrites and the instability of the SEI film limit the practical application of lithium metal materials. Despite this, lithium metal is still an ideal anode material to meet the growing demands for electronic equipment and electric vehicles due to its extremely high theoretical specific capacity, low density, and the lowest negative electrochemical potential. With the urgent need to develop new energy storage technologies, the research on lithium metal anodes has once again received extensive attention. In this review, the research progress in the modification of composite lithium metal electrode materials is summarized, including lithium/alloy composite electrode, lithium/carbon-based materials composite electrode and artificial SEI film. The possible directions for future development of lithium metal electrode are also prospected.

Low infrared emissivity in 3–5 μm or 8–14 μm band has been realized in different host materials. Realizing the low infrared emissivity in single material covering the entire band is rarely achieved. This research explores a binary system of ultra-high temperature ceramic ZrB2–CeO2 composites prepared by solid state sintering. their phase composition, microstructure evolution, reaction mechanism and infrared emissivity performance were discussed in detail. It was found that CeO2, ZrB2, ZrO2, and ZrnCe1-nO2 existed in the sample in addition to the coated glass phase of CeO2 on the surface of the sample. In-situ HRTEM results clearly revealed a series of reaction mechanism of CeO2 and ZrB2. With the increase of sintering temperature, the CeO2 particles gradually transformed into a glass phase, and were distributed on the surface of ZrB2 particles, and ZrO2 was formed on the surface of ZrB2, simultaneously. Consequently, ZrnCe1-nO2 is formed as the reaction of ZrO2 and CeO2. Compared with the infrared emissivity spectra of pure CeO2 and ZrB2, a low infrared emissivity less than 0.2 in a wider coverage band of 3–5 and 8–14 μm in ZrB2–CeO2 compounds was achieved as a result of synergistic interaction between CeO2 and ZrB2. The obtained information about the phase composition and microstructure evolution helps to realize low infrared emissivity in a wider coverage band in compounds via composition and microstructure modification.

K2SiF6:Mn4+ phosphor is well known for its excellent red emission performance which is vital for improving the color rendering of white light-emitting diodes. However, the poor moisture resistance limits its application in optical devices. In this paper, K2SiF6:Mn4+ phosphor is coated with an inorganic hydrophobic protective layer to obtain good moisture resistance. Chemical vapor deposition method was used to decompose acetylene at high temperature, and the generated nanoscale carbon layer worked as a hydrophobic protective coating on the surface of the phosphor. Microstructure, compositions and properties of the synthesized K2SiF6:Mn4+@C phosphor were investigated in detail. It is found that most of the deposited carbon is coated on the surface of phosphor crystals in amorphous state. The carbon atoms are bonded with the fluorine element in K2SiF6:Mn4+ phosphor, forming carbon-fluorine (C–F) covalent bonds. The moisture resistance of K2SiF6:Mn4+@C phosphor is improved owing to the protection of the hydrophobic carbon. The relative emission intensity of K2SiF6:Mn4+@C phosphor could maintain 73% of the initial luminous intensity after immersing in the aqueous solution at room temperature for 8 h, whereas K2SiF6:Mn4+ phosphor without carbon coating was only 0.7% remaining of the initial value under the same conditions.

Hydrogen production from direct water electrolysis has long been pursued as a key that may revolutionize the hydrogen economy. With the rapid availability of electricity generated using renewable energy resources, this long-pursued target is now closer to reality than ever before. To date, most studies regarding electrocatalytic hydrogen evolution reaction (HER) are carried out in strong acidic/alkali electrolytes. However, hydrogen production from HER under extreme pH conditions has several drawbacks, including a corrosive working environment, the requirement of expensive anion/cation exchange membranes, and acidic/alkali withstanding electrocatalysts. The more sustainable approach to address these drawbacks is to deploy neutral/near-neutral electrolytes for HER. Regretfully, both theoretical discussions and practical applications regarding HER under neutral/near-neutral conditions are relatively rare and very elusive. In this review, we systematically discuss the current understandings of HER mechanisms under neutral conditions and analyze the influences of different types of neutral electrolytes. The most recent advances in the development of neutral HER electrocatalysts are summarized and exemplified, and general electrocatalyst design principles are highlighted. Lastly, we provide our perspective on the potential future research direction. We hope that this review inspires future endeavors to realize efficient HER for hydrogen production under neutral conditions.

Bifunctional catalysts for water-electrolysis are developed to simplify electrode- and cell-manufacturing. Hitherto, screening bifunction catalysts relies on experimental trials of high-performance cells and theoretical calculations of free-energy changes in the HER/OER intermediate steps, with high costs and constraints. Herein, we derive from the inevitable electrode-surface oxidation in water electrolysis and the semiconductor physics of such an oxidized electrode surface a band-diagram perspective: the oxidized electrode surface governing the catalytic activities in a bifunctional water-electrolysis cell should be a semiconductor with an effective bandgap not much larger than the HER-OER electrochemical potential gap of 1.23 eV. This perspective and its applications are elaborated with a set of experimental and DFT-computational results with FeP as a nominal bifunctional catalyst on nickel electrodes for the construction of a high-performance cell exhibiting 10 mA cm−2 at 1.40 V. The proposed “bandgap screening” is easy, low-cost, and applicable for expediting the development of new bifunctional catalysts.

Developing highly efficient magnetic microwave absorbers (MAs) is crucial, and yet challenging for anti-corrosion properties in extremely humid and salt-induced foggy environments. Herein, a dual-oxide shell of ZnO/Al2O3 as a robust barrier to FeSiAl core is introduced to mitigate corrosion resistance. The FeSiAl@ZnO@Al2O3 layer by layer hybrid structure is realized with atomic-scale precision through the atomic layer deposition technique. Owing to the unique hybrid structure, the FeSiAl@ZnO@Al2O3 exhibits record-high microwave absorbing performance in low-frequency bands covering L and S bands with a minimum reflection loss (RLmin) of -50.6 dB at 3.4 GHz. Compared with pure FeSiAl (RLmin of -13.5 dB, a bandwidth of 0.5 GHz), the RLmin value and effective bandwidth of this designed novel absorber increased up to ~ 3.7 and ~ 3 times, respectively. Furthermore, the inert ceramic dual-shells have improved 9.0 times the anti-corrosion property of FeSiAl core by multistage barriers towards corrosive medium and obstruction of the electric circuit. This is attributed to the large charge transfer resistance, increased impedance modulus |Z|0.01 Hz, and frequency time constant of FeSiAl@ZnO@Al2O3. The research demonstrates a promising platform toward the design of next-generation MAs with improved anti-corrosion properties.

Fluorinated carbon (CFx), a thriving member of the carbonaceous derivative, possesses various excellent properties of chemically stable, tunable bandgap, good thermal conductivity and stability, and super-hydrophobic due to its unique structures and polar C-F bonding. Herein, we present a brief review of the recent development of fluorinated carbon materials in terms of structures, properties and preparation techniques. Meanwhile, the applications in energy conversions and storage devices, biomedicines, gas sensors, electronic devices, and microwave absorption devices are also presented. The fluorinated carbon contains various types of C-F bonds including ionic, semi-ionic and covalent C-F, C-F2, C-F3 bonds with tunable F/C ratios. The controllable designing of C-F bonding and F/C ratios play a key role to optimize the properties of fluorinated carbon materials. Until now, the potential issues and future opportunities of fluorinated carbon are proposed. The present review will provide a direction for tuning C-F bonding and F/C ratios, developing a safe and efficient fluorination method and popularizing the applications of fluorinated carbon materials.

In the field of low temperature co-fired ceramic (LTCC), it remains a challenge to design the performance of LTCC with low permittivity less than 5. Here, the K2O– B2O3–SiO2–Al2O3 composites are prepared without the preparation of prior glass. Meanwhile, the factors of the CaO content on microstructure, phase structure and properties of the composites are considered systematically. The crystal structure measured by X-ray diffraction (XRD) shows that there are quartz and alumina as the crystal phases. The results reveals that the tailoring CaO content benefits sintering densification, low dielectric loss, great mechanical properties and low thermal expansion coefficient. As CaO content increases up to 2.8 wt%, the composites sintered at 850∘C have a dielectric constant of 4.94 and tanδ of 8 × 10−4 at 1 MHz, thermal expansion coefficient (CTE) of 8.5 ppm/∘C, and flexural strength of 150 MPa. As the mass fraction of CaO increases up to 3.2 wt%, the maximum flexural strength of 173MPa is achieved. The above study provides an effective approach for preparing the novel composites as a promising candidate for LTCC applications.

The interface characteristics of electrode materials are of tremendous value for supercapacitors, however, poor conductivity, instability in harsh reaction conditions and limited ion mobility in oxide materials are identified as immense challenges for generating high energy density without renouncing the power capability. Herein, a peculiar catalytic chemical vapour deposition (CCVD) approach is employed to decorate a very thin carbon capsules (CCs) on the surface of LiMn2O4 nanorods to synthesize a very active and uniformly distributed LiMn2O4/CCs nano-hybrid material with modified interface characteristics. The CCs not only provide the physicochemical protection as well as improve the electrical conductivity. As an electrode material, LiMn2O4/CCs possess the specific discharge capacitance of 451 F/g which is far superior to LiMn2O4 (304 F/g) at the current density of 0.5 A/g in 0.5 M Li2SO4 aqueous solution. In addition, the LiMn2O4/CCs exhibit an outstanding specific capacitance of 380 F/g even at a much higher current density of 8 A/g. Moreover, after 3000 charge and discharge cycles, LiMn2O4/CCs electrode retains nearly 95% of initial capacity, higher than that of spinel LiMn2O4 electrode which retains only 93%. This innovative technique can be adopted to construct a large variety of other nano-hybrid materials for consumer utilization in the field of supercapacitors.

Designing sensing materials with novel morphologies and compositions is eminently challenging to achieve high-performance gas sensor devices. Herein, an in situ oxidative polymerization approach is developed to construct three-dimensional (3D) hollow quasi-graphite capsules/polyaniline (GCs/PANI) hierarchical hybrids by decorating protonated PANI on the surface of GCs; as a result, an immensely active and sensitive material was developed for sensing ammonia gas at room temperature. Moreover, the GCs possessed a capsule-like hollow/open structure with partially graphitized walls, and PANI nanospheres were uniformly decorated on the GC surfaces. Furthermore, the inflexible and rigid 3D ordered chemistry of these materials provides the resulting hybrids with a large interfacial surface area, which not only allows for rapid adsorption and charge transfer but also provides the necessary structural stability. The 3D hollow GCs/PANI hybrids exhibit excellent performance; the GCs/PANI-3 hybrid is highly sensitive (with a response value of 1.30) toward 10 ppm NH3 gas and has short response and recovery times of 34 and 42 s, respectively. The GCs/PANI-3 hybrid also demonstrates a good selectivity, repeatability, and long-term stability, which are attributed to the substantial synergistic effect of the GCs and PANI. The design of such a unique 3D ordered framework provides a promising pathway to achieve room-temperature gas sensors for commercial applications.

In the field of low temperature co-fired ceramic (LTCC), it remains a challenge to design the performance of LTCC with low permittivity less than 5. Here, a novel glass mixture of K-Al-B-Si-O (KABS) and Zn-B-Si-O (ZBS) is introduced as a sintering aid of alumina to obtain ultralow-permittivity glass/Al2O3 composite. Meanwhile, the factors of glass mixture component on microstructure, phase structure and dielectric properties of the composites are considered systematically. The crystal structure measured by X-ray diffraction (XRD) shows that pure crystalline phase of ZnAl2O4 spinel can be attained by tailoring the component of the glass mixture. In case of mass ratio of KABS: ZBS equal to 6:4, it favors to efficiently increase the sintering densification of composite, and significantly benefit the low dielectric loss, good mechanical and thermal performances. In detail, the optimal glass/ceramic composites sintered at 850 °C for 2 h exhibit the bulk density of 2.89 g/cm3, er of 4.92 at 14 GHz and Q × f of 6873 GHZ, flexural strength of 202 MPa, thermal expansion coefficient of 5.5 ppm/°C. The above study provides an effective approach for preparing the novel composites as a promising candidate for LTCC applications.

Zirconium Boride is widely used as thermal protection materials. However, the characteristics of poor oxidation resistance of ZrB2 at high temperatures limits its applications. In order to improve the anti-oxidation performance of ZrB2, a novel method of doping LaF3 is adopted in present study. In the synthesis process of ZrB2 via carbothermal reduction method, LaF3 was introduced to the initial materials. Motivated by the slightly higher formation temperature of ZrB2 than the melting point of LaF3, a liquid glass phase composed of F and La was deposited on the surface of ZrB2, which naturally brought in oxygen starvation and contributed to improved oxidation resistance performance. The crystal lattice parameters and the anti-oxidation ability of ZrB2 are closely dependent on the added LaF3 content, which can ascribe to La3+/Zr2+ substitution and the amount of glass phase on the surface of ZrB2.

Summary: Additive engineering has become increasingly important for making high-quality perovskite solar cells (PSCs), with a recent example involving acid during fabrication of cesium-based perovskites. Lately, it has been suggested that this process would introduce dimethylammonium ((CH3)2NH2+, DMA+) through hydrolysis of the organic solvent. However, material composition of the hydrolyzed product and its effect on the device performance remain to be understood. Here, we present an in-depth investigation of the hydrolysis-derived material (i.e., DMAPbI3) and detailed analysis of its role in producing high-quality PSCs. By varying the ratio of CsI/DMAPbI3 in the precursor, we achieve high-quality CsxDMA1-xPbI3 perovskite films with uniform morphology, low density of trap states, and good stability, leading to optimized power conversion efficiency up to 14.3%, with over 85% of the initial efficiency retained after ∼20 days in air without encapsulation. Our findings offer new insights into producing high-quality Cs-based perovskite materials. : Energy Sustainability; Materials Characterization; Energy Materials Subject Areas: Energy Sustainability, Materials Characterization, Energy Materials

Structural instability and limited operational efficiency of sodium-ion battery (SIB) anodes, compared lithium-ion battery (LIB) anodes, are main hurdles for their large-scale applications that can be tackled using self-tunable electrode materials. Here, we created and utilized ultrathin partially-crystalline carbon nanocups (CNCs) that have the ability to self-tune their structure, contain highly tangled walls and present open framework for enhanced energy densities for SIBs and the outcomes are benchmarked with LIBs. The tangled wall structure offers enhanced spacings for ionic storage and the open framework supports enhanced mass transport, while partial-crystallinity of CNCs provides high conductivity and stabilizes the structure for long cycle life. The CNCs delivered high capacities up to 468 mAh/g for SIBs at 25 mA/g and 953 mAh/g for LIBs at 50 mA/g after 100 cycles, respectively, while bore excellent stability by delivering highly stable performance exceeding 1000 cycles for SIBs at 1.5 A/g and 5000 cycles for LIBs at 7.5 A/g (20 C) with only a loss of 0.013 mAh/g per cycle. Moreover, when tested in lower voltage ranges, the CNCs delivered unprecedented capacity of 368 mAh/g (0.01–2.0 V) for SIBs and 671 mAh/g (0.01–2.0 V) and 449 mAh/g (0.01–1.5 V) for LIBs at 25 and 50 mA/g, respectively, which indicate the usability of the CNCs in full-cells. The post-electrochemical characterizations revealed that the developed CNCs self-modified their interlayer spacings (average spacing increased to 0.44 nm from 0.42 nm) during charge-discharge to create additional voids for increased ionic storage and stable performance, especially for Na+, while maintaining their overall morphology, composition and structure. The structural design presented here will provide new pathways of tailoring carbonaceous nanostructures for future high-performance energy storage devices.

Most microwave absorbers lose their function under harsh working conditions, such as a high temperature and an oxidative environment. Here, we developed a heterogeneous ZrN0.4B0.6/SiC nanohybrid via combined catalytic chemical vapor deposition (CCVD) and chemical vapor infiltration (CVI) processes using ZrB2 as the starting material. The composition and structure of the ZrN0.4B0.6/SiC nanohybrid were controlled by tuning the CCVD and CVI parameters, such as reaction temperature, time, and reactant concentration. The optimal heterogeneous ZrN0.4B0.6/SiC nanohybrids were obtained initially by preparing ZrB2@C via the CCVD process at 650 °C for 30 min and the subsequent CVI at 1500 °C, where the ZrB2@C reacted with Si under N2. The ZrN0.4B0.6/SiC nanohybrid exhibited enhanced microwave absorption ability with a minimum reflection loss value of approximately -50.8 dB at 7.7 GHz, a thickness of ∼3.05 mm, and antioxidation features at a high temperature of 600 °C. The heterogeneous ZrN0.4B0.6/SiC nanohybrid possessed reasonable conductivity, leading to dielectric loss, whereas SiC nanofibers formed a three-dimensional network that brought higher dipole moments, whereas a small part of the ZrN0.4B0.6/SiC nanohybrid structure generated an effective interface for higher attenuation of microwaves. Therefore, these material features synergistically resulted in a well-defined Debye relaxation, Maxwell-Wagner relaxation, dipole polarization, and the quarter-wavelength cancellation, which accounted for the enhanced microwave absorption.

ZrB2-based ceramics with different microstructures were prepared through different processes. Electrical resistivity of all samples was measured under vacuum environment by four-probe method over temperature range from 50 to 1000 °C. It was found that electrical resistivity and internal interface electrical resistivity of all samples increased linearly with environmental temperature. All samples showed nearly equal values of α, which was calculated using the formula: ρ(T1) = ρ(T0)+α·ρ(T0)·(T1-T0). This might be due to the fact that ZrB2 acted as electrical conductive phase in all samples. The relationship between electrical properties and microstructure of ZrB2-based ceramics was investigated. Increase in volume fraction of insulating phase and increase in internal interface electrical resistance can both cause effective electrical resistivity of ZrB2-based ceramics to increase. Internal interface electrical resistance was influenced by oxide impurities on the surface of ZrB2 particles and average particle size of ZrB2 particles.

Current study aimed at investigating oxidation behaviour of plasma-sprayed ZrB2-SiC coatings, which were deposited using different spray powers. Moreover, oxidation tests were carried out within temperature range of 400–1200 °C. Results from X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) suggested that ZrB2-SiC coatings had been markedly oxidized at 600 °C. Besides, oxidation behaviour of ZrB2-SiC block ceramics, which had achieved different densities using spark plasma sintering (SPS) and pressureless sintering (PS), was also studied to explain oxidation behaviour of plasma-sprayed ZrB2-SiC coatings. Results revealed that high-density ZrB2-SiC block ceramics displayed better oxidation resistance than low-density counterparts, indicating that unfavorable oxidation resistance of ZrB2-SiC coatings could be ascribed to low density, since there were more pores in ZrB2-SiC coatings, which provided channels for oxygen diffusion.

Development of high-performance materials for electromagnetic wave absorption has attracted extensive interest, but it still remains a huge challenge especially in reducing density and lowering filler loading. Herein, a hierarchical all-carbon nanostructure is rationally designed as follows: the defect-rich hollow graphite capsules (GCs) controlled by the size/density of ZnO templates are synthesized on the surface of helical carbon nanotubes (HCNTs) to form a hybrid nanocomposite, denoted as GCs@HCNTs. As a result, the GCs@HCNTs demonstrate a strong and wide absorption performance with a very low filler loading of 10 wt %. The minimum reflection loss reaches -51.7 dB at 7.6 GHz, and the effective bandwidth (below -10 dB) ranges from 8 to 14 GHz, covering the whole X or Ku bands. The hierarchical nanostructure and homoatomic heterogeneous interface are beneficial to impedance matching and bring additional dipole polarization enhanced by the structural defects, which may enlighten the design of ultralight and broadband high-performance electromagnetic wave absorption materials.

Phosphides of transition metals (TMPs) are a developing class of materials for hydrogen evolution reaction (HER) as an alternative to expensive noble metals to produce clean energy. Herein, the nitrogen-doped molybdenum oxide (MoOx) is developed via a facile and simple hydrothermal method, followed by annealing in the N2 atmosphere and phosphorization to form a nitrogen-doped oxygenated molybdenum phosphide (N-MoP) sphere-shaped structure. The developed N-doped phosphide structure depicts enhanced HER activity by reaching a current density of 10 mA cm-2 at a very low overpotential of only 87 mV, which is much better than annealed nitrogen-doped molybdenum oxide (A-MoOx) 138 mV in alkaline medium. N-MoP is a highly efficient electrocatalyst for HER attributed to a more exposed surface, large electrode/electrolyte interface and appropriate binding energies for reactants. This study extends the opportunity of developing nitrogen-doped TMPs, which can display exceptional properties as compared to their oxides.

Exploring efficient microwave absorbers at high temperature is a hot topic in the practical application. Non-isothermal oxidation kinetics of FeSiAl alloy powder sized of ∼45 μm were investigated by thermogravimetry analysis (TG) and differential scanning calorimetry (DSC) under linear temperature control program (ranging from 30 to 1200 °C) at different heating rates (5, 10, 15, 20 and 25 K/min) in air. It can be found that the melt point of FeSiAl alloy powder is about 1165 °C. The oxidation of FeSiAl alloy powder can be divided into two stages including solid-oxidation stage (before melting) and liquid oxidation stage (after melting). Non-isothermal kinetic analysis of oxidation of FeSiAl alloy powder were performed by using Flynn-Wall-Ozawa (FWO) method. Besides, the surface morphology of particles present a smooth trend by scanning electron microscope. And the microwave absorption performance of FeSiAl alloy powder is confirmed to be a good potential candidate in case of high temperature with the lowest refection loss value of −25.14 dB and effective absorbing bandwidth in range of 4–18 GHz adjusting the thickness.

The oxidative degradation of ZrB2 ceramics is the main challenge for its extensive application under high temperature condition. Here, we report an effective method for co-doping suitable compounds into ZrB2 in order to significantly improve its anti-oxidation performance. The incorporation of SiC and WC into ZrB2 matrix is achieved using spark plasma sintering (SPS) at 1800 °C. The oxidation behavior of ZrB2-based ceramics is investigated in the temperature range of 1000 °C–1600 °C. The oxidation resistance of single SiC-doped ZrB2 ceramics is improved due to the formation of silica layer on the surface of the ceramics. As for the WC-doped ZrB2, a dense ZrO2 layer is formed which enhances the oxidation resistance. Notably, the SiC and WC co-doped ZrB2 ceramics with relative density of almost 100% exhibit the lowest oxidation weight gain in the process of oxidation treatment. Consequently, the co-doped ZrB2 ceramics have the highest oxidation resistance among all the samples.

The application of composites of carbon matrix and ferromagnetic nanoparticles as electromagnetic wave absorption materials has received extensive attention. In this study, we successful synthesized metal organic framework (MOF) with dodecahedron shape by the decomposition of Co-based precursor of zeolitic imidazolate framework (ZIF -67). And to further improve the absorbing performance, acetylene was introduced to obtain ultra-small Co/CNTs nanohybrids. During CVD process, Co nanoparticles of MOF cracked into Co nanocrystals catalyzing the growth of carbon nanotubes (CNTs). Among three composites of ZIF-67, MOF and Co/CNTs, the Co/CNTs presented the better performance for electromagnetic wave absorption. Particularly, the maximum reflection loss (RL) of Co/CNTs reached −49.16 dB in case of the absorber thickness of 2.5 mm. The excellent absorbing performance is more likely attributed to the novel structure and the double losses of magnetic Co and dielectric CNTs.

Taking into account the high demands and applications of amorphous SiO2 in various nanostructured forms, here we have synthesized various nanostructures of SiO2 including nanosprings, straight nanofibers, nanotubes and nanobelts. A simple catalytic chemical vapor deposition (CCVD) technique is developed where Si, SiO2 and graphene capsules are utilized as starting materials. The structural and chemical analysis of the as-prepared nanostructures confirms the amorphous nature of SiO2 and shows the minor existence of SiC, which acts as a growth directing agent for various shapes of SiO2. The electron microscopic observations delineate the morphologies of the as-prepared nanostructures with different shapes i.e. nano-fibers, tubes, springs and belts. It is observed that straight SiO2 fibers having diameter of ∼440 nm are thicker than the fibers (∼220 nm) constructing the nanosprings while the overall helical diameter falls in the range of 530–690 nm. The in-depth structural and morphological studies reveal that the growth mechanism of SiO2 nanostructures is in the vapor-liquid-solid (VLS) growth mode. The unique microstructures with special morphologies straight, helical and hollow shapes make them potential candidate for several functional applications such as nanoelectron-magnetic devices, mechanical sensor system and flexible energy storage devices.

Rare-earth metal (Eu) doped aluminum nitride has potential application as luminescence materials due to its unusual mechanical and physical properties, as well as high chemical stability. Here we investigate the energetics, local structure and optical and electronic properties by means of a combination of experimental observations (XDR, SEM, HR-TEM and XANES) and first-principles simulations. Present study has revealed that Eu ions are likely to be co-doped with O in the form of Eu-O pairs. Eu ions or Eu-O pairs favor participation at the surfaces of the AlN crystallites. Our analyses show dependences of the Eu valence and electronic/optical properties on the local chemical composition and structure. The obtained information helps us to realize tuning of the optical properties of the luminescent materials via composition and site occupation modification. National Natural Science Foundation of China. Grant Number: 51302029; Fundamental Research Funds for the Central Universities. Grant Number: ZYGX2015J110.

Performing carbon coating on the surface of phosphors has been proven to be an effective strategy to enhance the oxidation resistance, which is an important factor to achieve stable luminescent devices. Therefore, a good understanding of the protection mechanism favors a continuous improvement of oxidation resistance of phosphors. In present paper, the evolution of the carbon layer, Eu valence (Eu 2+ /Eu 3+ ), and luminescent properties for the C coated BaMgAl 10 O 17 : Eu 2+ phosphor when annealed at high temperature is investigated carefully. Decrease of carbon layer promotes the appearance color transition from black to white as the annealing temperature rises to 1000 °C in air. As expected, the decrease of carbon layer will enhance the luminescence intensity, but risk the possible oxidation of Eu 2+ to Eu 3+ , which inhibits the blue emission ascribed to Eu 2+ . The results indicate that luminescence intensity of phosphor is dependent on the synergistic effect of carbon thickness and Eu 2+ /Eu 3+ ratio. Additionally, a reduction reaction of Eu 3+ to Eu 2+ is observed in C coated BaMgAl 10 O 17 : Eu 2+ phosphor when annealed at high temperature, which also contributes to the higher luminescence intensity.

Microwave absorption is a critical challenge with progression in electronics, where fine structural designing of absorbent materials plays an effective role in optimizing their microwave absorption properties. Here, we have developed Fe3O4@C (FC) and Fe-Fe3O4@C (FFC) hybrid nanorings via a hydrothermal method coupled with a chemical catalytic vapor deposition technique. FC and FFC hybrid nanorings have fine carbon coating while their size can easily be tunable in a certain range from 80-130 to 90-140 nm. The optimized FC and FFC hybrid nanorings bear minimum reflection loss (RL) values of -39.1 dB at 15.9 GHz and -32.9 dB at 17.1 GHz, respectively, whereas FFC shows an effective absorption bandwidth (RL values < -10 dB) ranged from 5.2 to 18 GHz. Such an enhanced microwave absorption performance of hybrid nanorings is mainly due to the suitable impedance characteristics, multilevel interfaces, and polarization features in nanorings. This work provides an approach to design hybrid materials having a complex structure to enhance the microwave absorption properties.

A facile approach to fabricate nanoholes on the surface of a phosphor via a carbothermal reaction between C and BaMgAl10O17 was adopted. Drilling nanoholes greatly enhanced excitation light absorption and consequently increased the quantum efficiency, which provided new insight to help improve the luminescence efficiency of oxygen-containing phosphors.

Superior thermal quenching and degradation of phosphors are required for long lifetime lighting devices, such as light-emitting diodes, which can be realized through composition modification. Here, Al-N bonds in AlON: Eu 2+ phosphors are substituted by higher bond order of Si-C. Photoluminescence (PL) results show thermal quenching (at 150 °C) and thermal degradation (after 600 °C treatment in air) are improved by 5% and 8% with a small decrease of PL intensity in 5% SiC doped AlON: Eu 2+ phosphor. To explain these observations, first-principles computational study was performed to understand the Si and C configuration in AlON:Eu 2+ . The calculations reveal that Si and C elements are not randomly distributed in AlON lattice. It was found that Si prefers occupying tetrahedral sites (Td-Si) and the insertion of C in Td-Si is always energetically favorable, which results in the formation of SiC 4 and SiNC 3 clusters. Thus, the Al-N substitution by Si-C induces a stronger local structure, which accounts for the emission redshift and better thermal stability.

Advanced microscopic technology opens up the opportunity of investigating the microstructure of novel materials and devices. In particular, high-resolution Atomic Force Microscopy (AFM) allows for the atomistic observation of materials for a variety of applications. To improve the imaging capability, several tip morphologies have been proposed to be employed in the AFM field. Among such morphologies, the carbon nanotube (CNT) has drawn extensive attention in recent years due to its high resolution and mechanical strength in imaging conditions. However, the exact theoretical basis for employing the nanotube in advanced AFM remains elusive up to this point. Here, we explore the theoretical basis for employing the nanotube morphology in advanced AFM. To do so, van der Waals (vdW) interaction between the nanotube and a planar disc, a key factor for achieving high imaging sensitivity, is evaluated. The results unanimously verify that nanotube morphology has unprecedented advantages over traditional cone-shaped AFM tips.

Copper nanostructures have aroused extensive research interests due to their large number of applications in phonology, electronics, catalysis, etc . Here, we have developed a novel single-step redox colloidal route to construct three-dimensional (3D) nanoporous Cu leaves. By tuning the surface chemistry of copper nuclei, the morphology of as-prepared copper nanocrystals can be adjusted from nanoparticles to leaves. The 3D Cu leaves own anisotropic nanoporous structure and exhibit surface-enhanced Raman scattering (SERS) performance with an enhancement factor of ∼10 6 . The present facile and low-cost route to develop 3D nanoporous Cu leaves provides an efficient platform for achieving high-performance nanostructures for next generation photocathode applications.

Designable control over the morphology and structure of active materials is highly desirable for achieving high-performance devices. Here, we develop a facile microwave-assisted synthesis to decorate MnO2 nanocrystals on three-dimensional (3D) graphite-like capsules (GCs) to obtain sandwich nanostructures (3D MnO2@GCs@MnO2) as electrode materials for electrochemical capacitors (ECs). A templated growth of the 3D GCs was carried out via catalytic chemical vapor deposition and MnO2 was decorated on the exterior and interior surfaces of the GC walls through microwave irradiation to build an engineered architecture with robust structural and morphological stability. The unique sandwiched architecture has a large interfacial surface area, and allows for rapid electrolyte diffusion through its hollow/open framework and fast electronic motion via the carbon backbone. Furthermore, the tough and rigid nature of GCs provides the necessary structural stability, and the strong synergy between MnO2 and GCs leads to hi...

In this study, hydroxyapatite-containing coatings were prepared by microarc oxidation on AZ31 magnesium alloy surface to improve its biodegradation performance. Five applied voltages were chosen to prepare the MAO coatings. The results demonstrate that the number of micropores in the films increases but their dimensions decrease after higher voltage is applied. As the surface roughness of the MAO coatings increases with the applied voltage, the wettability of the coatings improves continuously. The MAO coatings were mainly composed of magnesium oxide (MgO) and hydroxyapatite. The amount of hydroxyapatite phase increased with increasing voltage that was applied. The bonding strength became slightly weaker after a higher voltage was applied. But the bonding strengths of all the coatings were consistently higher than 37 MPa, which met the requirement of implant biomaterials. All coatings exhibited higher corrosion resistances and lower hydrogen evolution rate than the bare AZ31 Mg substrate, implying that the degradation rate of the AZ31 Mg alloy was enhanced by the hydroxyapatite-containing coatings. The results indicate that the present treatment of applying hydroxyapatite-containing coatings is a promising technique for the degradable Mg-based biomaterials for orthopedic applications.

As a novel alternative biodegradable metal, magnesium possesses great potential and feasibility for bone fracture fixation due to its suitable mechanical properties, high degradability and biocompatibility. However, poor corrosion resistance in physiological fluids restricts their practical applications. In this study, HA contained coating on AZ31 Mg alloy substrate is prepared by MAO technique under various treatment times. The effect of treatment time on microstructure, composition, mechanical and corrosion properties is systematically investigated. The results indicate that MAO treatment is an effective route to improve the corrosion resistance. The enhanced corrosion is attributed to the barrier effect of the coatings. The failure mechanism of the MAO samples in Hank's solution is studied by long time immersion. A model for corrosion mechanism and corrosion process of the MAO coating on AZ31 Mg alloy in Hank's solution is proposed.

Graphitic carbon (GC) coatings on the surface of functional materials have received tremendous attention because of their significant effect on surface chemistry. Herein, we have explained the interactions of a carbon source (acetylene) on the surface of functional material (tetrapod-zinc oxide, T-ZnO) through Density Functional Theory (DFT) calculations. DFT studies suggested that the growth of GC in the catalytic chemical vapour deposition (CCVD) process follows two typical pathways: one is chemo/physioadsorption of acetelyne on the T-ZnO surface, and the second one is decomposition of acetylene on the T-ZnO surface to activate carbon atoms that are restructured to generate a GC layer on the T-ZnO surface. Therefore, such a growth through catalytic accumulation reaction of carbon species on the substrate surface is named as vapour-dissociation-solid (VDS) growth. To support our theoretical observation, the GCs on the surface of T-ZnO are grown using acetylene through CCVD, and the results strongly support the VDS growth mechanism. The varying conditions of the CCVD process results in two types of microstructures including a smooth GC coating on T-ZnO that can also yield functional hollow GC nanostructures through acid leaching of the metallic part and ZnC8 nanoparticles embedded in GC walls. The high resolution microscopic analyses confirm the existence of ZnC8 in the nanospheres with an average size of 5.36 nm, which authenticates the decomposition followed by the solid deposition to form the GC on the substrate surface and supports a unique VDS growth mechanism. Therefore, an in-depth study of the GC growth mechanism and its fine coating on complex structures will facilitate research in the prevention of metal oxidation and the design of novel active materials for sensors, environment, energy and medical applications.

Early detection of peptide aggregate intermediates is quite challenging because of their variable and complex nature as well as due to lack of reliable sensors for diagnosis. Herein, we report the detection of monomers and oligomers using specified fluorescence and a magnetic resonance imaging (MRI) multimodal probe based on bovine-serum-albumin-capped fluorine functionalized graphene quantum dots (BSA@FGQDs). This probe enables in vitro fluorescence-based monitoring of human islet amyloid polypeptide (hIAPP), insulin, and amyloid β(1–42) (Aβ42) monomers and oligomers during the fibrillogenesis dynamic. Up to 90% fluorescence quenching of BSA@FGQDs probe upon addition of amyloid monomers/oligomers was observed due to static quenching and nonradiative energy transfer. Moreover, the BSA@FGQDs probe shows 10 times higher signals in detecting amyloid intermediates and fibrils than that of conventional thioflavin dye. A negative ΔG° value (−36.21 kJ/mol) indicates spontaneous interaction of probe with the pept...

Transition-metal dichalcogenides (TMDs), such as VSe2, are widely explored as promising hydrogen evolution reaction (HER) electrocatalysts, however, the catalytically inert basal planes remain a great challenge limiting the H2 evolution process. Herein, a defect-engineering approach is adopted to activate the inert basal planes of VSe2 by embedding Se vacancies in the crystal lattice via the sealed-quartz tube technology at controlled reaction conditions. The Se vacancies are introduced by tuning the molar ratio of V and Se powders which in situ forms V3+ to revamp the electronic configuration and expose more catalytic active sites favoring reduce the Gibbs free energy of hydrogen adsorption (△GH). The upgraded VSe2-1.8 delivers an overpotential value of 160 mV at a current density of 10 mA cm−2 which shows its superiority compared with the reported literatures. Not only that, a small Tafel slope 85 mV dec-1 and excellent stability for 48 h demonstrate its fast reaction kinetics and applicability for a long period of time. Moreover, the theoretical calculation results also indicate that introducing proper Se-vacancy density to form the separate defects on the basal plane of VSe2 can yield the optimal △GH, which achieve higher intrinsic HER activity. Furthermore, a high throughput synthesis device is designed for large-scale preparation of the catalysts which is much suitable for application at commercial level. The defect engineering technique to trigger more active sites provides a novel and efficient way to enhance HER performance of 2D TMDs.

Generally speaking, thermal stability is the key factor for microwave absorbers (MAs) at high temperature. In this paper, we first propose to apply a novel material called Cr2AlC (CAC) in the high temperature field. The self-made high purity CAC powder prepared by salt bath exhibits good microwave absorption performance and outstanding. Thermogravimetric (TG) analysis indicates the CAC begins to oxidize significantly above 800 °C. Moreover, the effective medium theory is adopted to calculate the microwave absorption performance for the CAC/paraffin composite material. We found that the sample with 70 wt% CAC (CAC70) has a minimum reflection loss of −25.09 dB at 11.08 GHz and its effective absorption bandwidth (below −10 dB) is 2.2 GHz (10.2–12.4 GHz) at the thickness of 2.00 mm, which indicates a thin layer of Al2O3 at room temperature will not affect the entry of electromagnetic waves and internal electrical losses. The high anti-oxidation layered structure CAC provides an opportunity to expand microwave absorption in high temperature applications.

Exploring effective microwave absorption materials is always a challenge especially in the relatively low frequency range of 2–8 GHz and broad absorption band. Here we developed a Fe 3 C/helical carbon nanotube (HCNT) hybrid structures synthesized via catalytic chemical vapor deposition (CCVD) using Fe 3 O 4 nanoparticles as catalyst. The microwave-absorbing characteristics of such hybrid nanomaterials were investigated based on the transmission line theory through the evaluation of the experimental data including complex permittivity and permeability. Considering the reaction temperature range of 400–750 °C, the as-prepared hybrid synthesized at 700 °C can be adjusted to have effective performance of RL value less than −10 dB in the relatively lower frequency ranged from 2.9 GHz to 9.9 GHz at the thickness range of 2–5 mm. Furthermore, the hybrid in case of 750 °C bears bandwidths with RL lower than −10 dB from 7.3 GHz to 18 GHz and the minimum RL is about −21 dB. The observed advantageous reflection loss was attributed to the pronounced impedance match owing to the reasonable synergistic effect between magnetic nanoparticles and HCNTs.

Two-dimensional graphene is easy to aggregate and hard to transfer because of the van der Waals forces between graphene layers. The three-dimensional (3D) graphite-like capsules (GCs) disperse well and exhibit robust structural stability and have a potential for promising applications in energy storage, drug delivery, catalyst substrate, etc. Here, we develop a catalytic chemical vapor deposition route for the synthesis of 3D GCs with unprecedented thickness and morphology control. The theoretical results indicate that the strong chemisorption and charge transfer between ZnO and acetylene allow the layer-by-layer formation of GCs that is later confirmed by the experimental data. The 3D GCs are synthesized with thickness control from three atomic layers to ∼300 atomic layers over various oxides with predesigned shapes of microscale tetrapods, nanospheres, nanorods, nanocubes, etc. In particular, the formation mechanism of GCs is investigated using the ZnO surface as a catalyst through systematically experi...

Zirconium diboride exhibits high thermal conductivities and high melting point, which are beneficial for use in extreme environments. Examples including cutting tools, high-temperature electrodes and leading edges of hypersonic space vehicles. However, there is limited literature on the infrared properties of ZrB2 thin films. In this study, we report the results of infrared emissivity of sputter-deposited films and post-annealed films. X-ray diffraction shows promoted crystalline quality and grains growth for ZrB2 films with the increasing annealing temperature and time. The thin film exhibits high thermal stability and a low infrared emissivity of 0.01 (8 ~ 14 μm) after annealed at 1000℃ for 10 h. Besides, with an increase in annealing temperature and annealing time, film densification and grains growth were observed, leading to decrease of electrical resistivity and infrared emissivity.

As a promising material for electromagnetic microwave absorption, FeSiAl (FSA) alloy always suffers from inadequate corrosion resistance in the marine environment. Herein, the Raman and X-ray photoelectron spectroscopy (XPS) depth profiling techniques are adopted to investigate the basic corrosion behavior of FSA in salt spray environment. The Raman analysis contributes to the understanding of the composition change at various corrosive periods while the XPS depth profiling reveals the corrosion process of Fe0→Fe2+→Fe3+ in a sequence. The observed corrosion rates (CRs) of FSA immersed in 5 wt% NaCl solution for 1, 24 and 48 h are 2.99 × 10−12, 4.90 × 10−12 and 5.85 × 10−12 m/s, respectively. The increasing value of CRs as a function of time demonstrates the accelerated corrosion tendency. Moreover, to suppress the corrosive behavior of FSA alloy, carbon is decorated on its surface by catalytic chemical vapor deposition method using acetylene as the carbon source. The carbon coating restrains the corrosion process by impermeability and hydrophobicity of carbon materials in corrosive mediums. This study will help in the designing of microwave absorbers which can resist corrosion in harsh reaction conditions as well as available at commercial level to save the economy.

Designing of materials which can resist aging and corrosion in harsh reaction conditions is required to mitigate the omnipresent issue of electromagnetic interference pollution. Particularly, FeSiAl alloy is a relevant composite material, however, it always suffers aging and corrosion when exposed to crude saline environment. Herein, Carbon-encapsulated FeSiAl (FeSiAl@C) hybrid flakes are developed by catalytic chemical vapor deposition (CCVD) technique through the reaction of FeSiAl precursor with acetylene (C2H2) gas at 300 °C for 5 min. The carbon coating efficiently improves the impedance matching characteristics of FeSiAl powder leading to enhance microwave absorption. Not only that, the carbon capsule also plays an effective shielding function to prevent the alloy from corroding. Specifically, the FeSiAl@C-300 °C delivers increased complex permeability and permittivity in the frequency range of 7–14 GHz, as well as improved impedance matching. In addition, the corrosion resistance is measured using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) in 5 wt% NaCl solution. The results indicate that the synthesized hybrid exhibits excellent corrosion resistance capability. So, the composite synthesis is a worthy approach to design hybrid materials for effective microwave absorption and corrosion resistance properties for practical applications.

Structural and chemical stability is the key factors of microwave absorbers for their applications in case of high-temperature oxidation. In this study, a plasma-induced method is developed to get a multistrata core-shell structure of FeSiAl@Al2O3@SiO2 with bifunctional performances of microwave absorption and anti-oxidation. Within a dense microstructure, the Al2O3 and SiO2 ceramic shell layers mitigate oxygen transport to prevent corrosion at high temperature. Consequently, the magnetic FeSiAl core is well-protected against oxidation up to 1279 °C in air and exhibits excellent microwave absorption property. In particular, dense ceramic layers effectively reduce the permittivity of FeSiAl without losing permeability. Furthermore, the novel FSA@GCLs microstructures are enriched with multiple interfaces to favor the interfacial polarization and vast internal scattering probabilities. Because of the strong synergistic magnetic-dielectric effects, the multistrata core-shell structure of FeSiAl@Al2O3@SiO2 owns a minimum reflection loss of −46.29 dB at 16.93 GHz and its wide bandwidth (with an RL value of −10 dB) particularly acquire 7.33 GHz in the frequency range of 10.14–17.45 GHz. The highly stable multistrata core-shell opens up the opportunities of extending the microwave absorption as well as anti-oxidation applications.

In rechargeable lithium ion batteries (LIBs), the separator undergoes stresses in repeated charge and discharge processes. Polyvinylidene fluoride (PVDF) gel separators own excellent thermal stability and electrolyte wettability, but their limited mechanical strength cannot sustain severe strains under the conditions of large Li ion fluxes, mechanical and thermal shocks of batteries. In this report, a solid-electrolyte-reinforced gel separator is prepared through a single-step electrophoretic deposition on a stable surfactant-free colloid of PVDF-HFP and Al-doped Li6.75La3Zr1.75Ta0.25O12 (LLZTO). The LLZTO/PVDF-HFP separator owns a 3D laminated structure, a mechanical strength of 28.6 MPa, a room-temperature ionic conductivity of 7.13 × 10−4 S cm−1 and improved thermal stability. With the LLZTO/PVDF-HFP separator, LiFePO4 LIBs deliver a threshold discharge capacity of 170 mAh g−1 at 0.1 C and stable cycling with nearly zero capacity decay over 100 cycles at 0.5 C.

Aerospace vehicles are subjected to high temperatures because of surrounding aerodynamic drag and the formation of large temperature gradients across the external structural parts of their airframe. To protect the vehicles, high-infrared emissivity coatings that can radiate a large amount of heat into outer space are in demand. In this work, we describe the development and characterization of high emissivity ceramic coatings formed on a TC4 alloy surface by micro-arc oxidation. We evaluate, in particular, the influence of NiSO4 concentration on current-time response, the thickness, surface roughness, morphologies, bonding strength, and emissivity of these coatings. The results indicate that by increasing the NiSO4 concentration in electrolytes, the thickness and surface roughness of the coatings increase. The bonding strength becomes smaller with increasing concentration of NiSO4, but is still maintains a value higher 30 MPa. The coatings possess good thermal shock resistance after being subjected to severe thermal shocks for 50 cycles, and no peeling of the coating is observed. A higher concentration of NiSO4 in electrolytes also leads to an increasing percentage of the nickel components in the coating to form a NiO phase, which enhances the emissivity of the coatings in the wavelength range of 3-8 μm.

Traditional photocatalysts are difficile to conform the provision of visible light catalysis, conducive recycling and eminent efficiency, which limits their practical applications for decomposing organic pollutants in wastewater. Herein, a multi-layered porous hierarchical titanium dioxide/graphitic carbon nitride (TiO2/g-C3N4) hybrid coating is in-situ generated on titanium (Ti) substrate by sequentially employing plasma electrolytic oxidation (PEO), alkali immersing and hydrothermal reaction. The as-prepared coating exhibits surpassing photocatalytic performance to decay Rhodamine B (RhB) than g-C3N4 and TiO2 photocatalysts under 5 W LED visible light with 240 h cyclic stability. Moreover, the electrons transport and Z-scheme mechanism for TiO2/g-C3N4 hetero-junction is pursued to account for the ultralow recombination of photo-induced electron-hole and the enhanced catalytic properties. Not only that, it inhibits the secondary pollution which has further intensified its significance for degradation of organic pollution in sewage treatment systems.

Cobalt selenide@reduced graphene oxide (CoSe2@rGO) nanohybrid was successfully synthesized by a facile one-pot hydrothermal method and the electrochemical performance of the nanohybrid was evaluated for supercapacitor applications. The CoSe2@rGO nanohybrid show superior electrochemical performance in terms of the specific capacitance (449 F g−1 at 2 mV s−1, 219 F g−1 at 0.5 A g−1) and enhanced cyclic stability (91.3% capacitance retention for 5000 cycles) relative to pure CoSe2 (196 F g−1 at 2 mV s−1, 99 F g−1 at 0.5 A g−1). Such a highly improved specific capacitance found in the CoSe2@rGO nanohybrid electrode is mainly attributed to the nanosized CoSe2 grains with perfect redox property, more electro-active sites induced by synergetic effect at the interface of CoSe2 and rGO, and high specific area of rGO nanosheets. Besides, with the combination of rGO, the electrical conductivity of the CoSe2@rGO nanohybrid is highly enhanced, the ion/electron diffusion path is also reduced leading to faster charge transport during charging/discharging process with an improved cyclic stability.