Unique Layered Structure Research Articles

Vertically aligned MoS2 nanosheets on monodisperse MXene as electrolyte-philic cathodes for zinc ion batteries with enhanced capacity.

Zinc ion batteries (ZIBs) have attracted extensive attention for their high safety and environmentally friendly nature, and considerable theoretical capacities. Due to its unique two-dimensional layered structure and high theoretical specific capacities, molybdenum disulfide (MoS2) presents as a promising cathode material for ZIBs. Nevertheless, the low electrical conductivity and poor hydrophilicity of MoS2 limits its wide application in ZIBs. In this work, MoS2/Ti3C2Tx composites are effectively constructed using a one-step hydrothermal method, where two-dimensional MoS2 nanosheets are vertically grown on monodisperse Ti3C2Tx MXene layers. Contributing to the high ionic conductivity and good hydrophilicity of Ti3C2Tx, MoS2/Ti3C2Tx composites possess improved electrolyte-philic and conductive properties, leading to a reduced volume expansion effect of MoS2 and accelerated Zn2+ reaction kinetics. As a result, MoS2/Ti3C2Tx composites exhibit high voltage (1.6 V) and excellent discharge specific capacity of 277.8 mA h g-1 at 0.1 A g-1, as well as cycle stability as cathode materials for ZIBs. This work provides an effective strategy for developing cathode materials with high specific capacity and stable structure.

Emerging 2D pnictogens: a novel multifunctional photonic nanoplatform for cutting-edge precision treatment.

The elements of the pnictogen group, known as the 15th (VA) family in the periodic table, including phosphorus (P), arsenic (As), antimony (Sb) and bismuth (Bi), have been widely used by alchemists to treat various diseases since ancient times and hold a pivotal position in the history of medicine, owing to their diverse pharmacological activities. Recently, with the development of modern nanotechnology, pnictogen group elements appear in a more innovative form, namely two-dimensional (2D) pnictogens (i.e. phosphorene, arsenene, and bismuthene) with a unique layered crystal structure and extraordinary optoelectronic characteristics, which endow them with significant superiority as a novel multifunctional photonic nanoplatform for cutting-edge precision treatment of various diseases. The puckered layer structure with ultralarge surface area make them ideal drug and gene delivery vectors that can avoid degradation and reduce target effects. The anisotropic morphology allows their easier internalization by cells and may improve gene transfection efficiency. Tunable optoelectronic characteristics endow them with excellent phototherapy performance as well as the ability to act as an optical switch to initiate subsequent therapeutic events. This review provides a brief overview of the properties, preparation and surface modifications of 2D pnictogens, and then focuses on its applications in cutting-edge precision treatment as a novel multifunctional photonic nanoplatform, such as phototherapy, photonic medicine, photo-adjuvant immunotherapy and photo-assisted gene therapy. Finally, the challenges and future development trends for 2D pnictogens are provided. With a focus on 2D pnictogen-based multifunctional photonic nanoplatforms, this review may also provide profound insights for the next generation innovative precision therapy.

Graphene/h-BN Nanosheet/Nanosphere Composites Constructed by In Situ Laser Irradiation with Synergistically Improved Tribological Performance

Graphene/hexagonal boron nitride nanocomposites with different dimensions have great application prospects in the field of lubrication due to their unique layered structure and excellent mechanical properties. However, due to their complex synthesis process, easy agglomeration, and poor stability, graphene/hexagonal boron nitride nanocomposites have not yet been applied in lubricating applications. Herein, a simple and green in situ laser irradiation method is proposed to construct two-dimensional (2D) reduced graphene oxide (rGO) nanosheets and zero-dimensional (0D) hexagonal boron nitride nanosphere 2D/0D nanocomposite (L-rGO/h-BN). During the one-step laser irradiation in liquid, the GO nanosheets were reduced to rGO nanosheets. Meanwhile, the hexagonal boron nitride (h-BN) transformed from nanoflakes to nanospheres via a pulsed laser heating and reshaping process and embedded into the multilayer graphene nanosheets. The spherical h-BN nanoparticles as interlayer support can maintain the 2D graphene with a more stable layered structure, while the insertion of graphene sheets also effectively inhibits the agglomeration of the spherical h-BN nanoparticles. Therefore, a hierarchical 2D/0D layered rGO/h-BN nanocomposite was formed. Importantly, such composite nanoparticles can well disperse in the lubricating oil without significant precipitation for over 30 days and show remarkably improved tribological performance. This is due to the synergistic lubricant effect of the deposition repair effect from rGO nanosheets reducing wear and micro-bearing effect from h-BN nanospheres reducing friction by changing sliding friction into rolling friction.

Opioid Drug Detection in Hair Samples Using Polyoxometalate-Based Frameworks

A series of two-dimensional (2D) polyoxometalate-based frameworks, [Ln3(PDA)3(H2O)6(PMo12O40)]·xH2O (Ln = La (1); Ce (2); Pr (3); Nd (4); PDA = 1,10-phenanthroline-2,9-dicarboxylate), have been synthesized and structurally characterized by various analytical techniques. Single-crystal X-ray diffraction reveals that 1-4 have a unique 2D layer structure in which Keggin anions have coordinated upward and downward the plane, and this feature makes them suitable candidates for surface binding of common drugs via supramolecular and electrostatic interactions. Also, the ability of 1-4 (as the first polyoxomolybdate-containing frameworks) as sorbents for the extraction and quantitative determination of opioid drugs (morphine, methadone, and pethidine) was investigated by using dispersive micro-solid-phase extraction (D-μSPE) and high-performance liquid chromatography (HPLC). The method showed wide linear ranges in the range of 0.3 to 300 ng mg-1 and low limits of detection (LODs) ranged from 0.1 to 0.2 ng mg-1 of hair.

Construction of diphenic acid molecular welded Ti3C2 with enlarged and stable interlayer spacing towards high rate alkali metal ions storage

Ti3C2-MXene has been generally studied in energy storage area because of adjustable surface chemistry, excellent electronic conductivity, and unique layered structure. However, the diffusion kinetic performance of alkali metal ions in Ti3C2 is restricted by the limited interlayer spacing. Enlarging interlayer spacing of Ti3C2 is beneficial to improve the ion diffusion rate. Here, a simple and effective diphenic acid (DHA) molecular welding strategy is reported to prepare DHA welded Ti3C2 (DHA-Ti3C2) by dehydration condensation reaction. The welded DHA molecule contributes the dual effects of pillar and strain on the layered structure of Ti3C2, which can improve ion diffusion kinetic performance and alleviate volume expansion during the alkali metal ions insertion/extraction process. The DHA-Ti3C2 exhibits high rate capability and long-term cycle stability because of the enlarged interlayer spacing and enhanced structure stability. The specific capacity of 444 mAh g−1 and 156 mAh g−1 at current density of 0.1 A g−1 can be reached after 200 cycles and 1700 cycles in Li+/Na+ batteries, respectively. This study offers a strategy to efficiently tuning the layered structure of two-dimensional (2D) materials for achieving the optimal alkali metal ions storage performance.

Assessment of the electrodeposition synthesized manganese chromite and cobalt‑nickel layered double hydroxide composite for high-performance supercapacitor applications

Cyclic voltammetry (CV) electrodeposition synthesis was performed twice to synthesize manganese chromite (MnCr2O4-ϕ) on NF, where −1.4 ≤ ϕ ≤ − 1.0 is the lower voltage (V vs Ag/AgCl) set in the CV during electrodeposition, the higher potential being 0.5 V. This was followed by another electrodeposition of cobalt nickel layered double hydroxide (CoNi-LDH) on MnCr2O4-ϕ. The unique layered structure of CoNi-LDH produce electrodes with excellent electrochemical performance. MnCr2O4–1.2 V@CoNi-LDH (ϕ = − 1.2 (V vs Ag/AgCl)) yielded the best electrochemical performance in three-electrode set-up in 2 M KOH with the highest specific capacity of 1529.3 C g−1 at a specific current of 1 A g−1. This electrode was incorporated into the hybrid device with activated carbon (AC) from Amarula Husk as the negative electrode (AMH). The device (MnCr2O4-1.2 V@CoNi-LDH//AMH) produced a superb specific energy of 80.2 Wh kg−1 corresponding to a specific power of 1117.7 W kg−1 at 1 A g−1. The device also showed the capacity retention and Coulombic efficiency of the device were 72.9 and 99.7 %, respectively after 15,000 GCD cycles at 9 A g−1. Due to the phenomenal performance, the produced materials are suitable candidates for high energy supercapacitor applications.

Oxygen-rich vacancies CuCoLDH with 1D/2D nanoarray structure for high performance asymmetric supercapacitor

The performance of optimization layered double hydroxide (LDH) electrodes via oxygen vacancy engineering is of great significance for high-performance hybrid supercapacitors. Herein, we obtain oxygen-rich CuCoLDH (Ov-CuCoLDH) nanoarray structure by in-situ etching of Co-MOF nanorods and subsequent NaBH4 reduction. The addition of oxygen vacancy does not affect the original unique layered structure and creates more active centers, promoting faster electron transfer and ion conversion. Moreover, this method maximizes the synergistic effect between copper and cobalt ions. The as-assembled Ov-CuCoLDH electrode shows an outstanding specific capacity of 1392.4 F g−1. Furthermore, forming the Ov-CuCoLDH and AC electrodes possesses 58.2 W h kg−1 of energy density (at a power density of 850 W kg−1). At the end of 10,000 cycles, the CF@Ov-CuCoLDH//AC device keeps 86.7 % of the original capacitance, indicating a high degree of stability. The results show that the strategy of introducing oxygen vacancy by a mild and effective method to improve the capacity of LDH has a certain guiding significance for designing higher-performance electrode materials.

Construction of porous carbon nanosheets by dual-template strategy for zinc ion hybrid capacitor

Carbonaceous zinc ion hybrid capacitors (CZHCs) have attracted numerous interests thank to the advantages of large energy density of zinc-ion battery and excellent security and high power density of supercapacitors. Nevertheless, the preparation of carbon cathode is relatively complex, and it is urgent to develop a simple and efficient preparation method. Herein, the porous carbon nanosheets (C-Xs) were prepared by dual-template strategy combined K2CO3 activation from anthracene molecules, which present unique layered sheet-like structures and high surface area, displaying excellent zinc storage properties as cathode for Zn‖C-X ZHCs. Zn‖C-800 ZHC achieves high discharge capacity of 121.7 mAh g−1, maximum energy density and power density of 109.3 Wh kg−1 and 15.6 kW kg−1 in 3 M ZnSO4 electrolyte, respectively. Moreover, the capacity retention of 96.2% and coulombic efficiency of ∼100% is obtained after 30,000 cycles. This work opens up a simple and efficient rout for the synthesis of carbon nanosheet cathode by dual-template strategy for ZHC.

Recent Advances of Transition Metal Sulfides/Selenides Cathodes for Aqueous Zinc‐Ion Batteries

AbstractRechargeable aqueous zinc‐ion batteries (ZIBs) have aroused tremendous attention in energy storage system due to their high safety, eco‐friendliness, low cost, and for their good compatibility. Transition metal sulfides and selenides are considered to be promising cathodes for aqueous ZIBs owing to their unique layered structure and tunable interlayer spacing for the accelerating diffusion and reversible intercalation of hydrated Zn2+. However, their practical applications are severely impeded by some defects, such as the inferior electronic conductivity, large ion diffusion energy barrier, and bad cyclic stability. In this review, the various modification strategies including phase engineering, defect engineering, interlayer intercalation, in situ electrochemical oxidation, hybridization, doping effects, and surface modification are categorized and highlighted to improve the electrochemical properties of transition metal sulfides and selenides cathode materials, which are discussed and summarized corresponding to particular modification strategies. Finally, several key breakthrough directions such as mechanism exploration technology, electrolyte strategies, synergistic engineering, high‐capacity conversion‐type, high‐voltage cathode materials, and rocking‐chair type batteries are proposed to further push forward the development of aqueous ZIBs, to guide the design of advanced‐properties cathode materials for aqueous ZIBs.

Single-atom nanozymes Co–N–C as an electrochemical sensor for detection of bioactive molecules

A properly designed sensing interface is crucial for the accurate and sensitive detection of biologically active molecules. Single-atom nanozymes from transition metal and nitrogen-doped carbon materials (M-N-C) have caught attention owing to their large surface area and strong bionic enzyme activity. Herein, a three-dimensional layered electrochemical electrode consisting of a Co–N–C nanoenzyme embedded in a reduced graphene oxide aerogel was prepared for the detection of hydrogen peroxide (H2O2), dopamine (DA) and uric acid (UA). Due to its unique three-dimensional layered structure, rGA has excellent electrical conductivity and high material loading and is used to enhance the electrocatalytic performance of Co–N–C. The combination of single-atom nanozymes and electrochemical detection shows unique advantages in catalytic activity and selectivity. The limit of detection and detection range are 0.74 μM and 3–2991 μM respectively for H2O2. Furthermore, it has been successfully implemented for the in-situ detection of H2O2 in living cells. In addition, their simultaneous detection is also realized by the sensors for DA and UA. And it can accurately capture the signal of UA and DA in the urine. Meanwhile, the electrode displays satisfactory stability and repeatability. Therefore, this paper provides a new detection strategy for a variety of bioactive molecules, showing great potential in cell biology, pathophysiology and diagnostics.

Uniform Na3V2(PO4)2O2F microcubes enhanced by ionic liquid-modified multi-walled carbon nanotubes as a superior cathode for Sodium-Ion Batteries

Na3V2(PO4)2O2F with a typical Na+ superionic conductor (NASICON) structure is a promising cathode material for sodium-ion batteries (SIBs) due to its unique layered structure, high energy density and fast ionic conductivity. However, the low intrinsic electronic conductivity seriously hinders the practical application of Na3V2(PO4)2O2F. In this work, ionic liquid-modified multi-walled carbon nanotubes (MWCNT-IL) were applied as a conductive network to form Na3V2(PO4)2O2F-based cathode. The highly dispersed MWCNT-IL can hinder the agglomeration growth of Na3V2(PO4)2O2F crystal and can result in the formation of uniform Na3V2(PO4)2O2F cubes of ∼1 μm which are covered evenly by conductive MWCNT-IL through COP/V bonds (denoted as NVOPF@MWCNT-IL). Relying on the synergistic effect of conductive MWCNT-IL and uniform Na3V2(PO4)2O2F cubes, NVOPF@MWCNT-IL cathode for SIBs can exhibit improved cycling stability and superior rate performance. The specific capacity of NVOPF@MWCNT-IL can reach 107 mA h g−1 with high retention of 96.7% after 900 cycles at a current density of 1C (1C=130 mA h g−1). At a high current density of 30C, NVOPF@MWCNT-IL maintains a high discharge capacity of 79 mA h g−1 after 1500 cycles. The above results provide an effective and simple method to construct advanced NASICON cathodes for SIBs.

Synthesis and Visible Light Catalytic Performance of BiOI/Carbon Nanofibers Heterojunction

Semiconductor materials as photocatalysts hold great prospects for renewable energy substitutes and environmental protection. Nanostructured BiOX (X=Cl, Br, I) with favorable features of a unique layered crystal structure and suitable band gaps has been demonstrated to be a promising photocatalytic material. In this paper, a two-step synthesis route combining an electrospinning technique and SILAR reaction has been accepted as a straightforward protocol for the exploitation of BiOI/carbon nanofibers’ (CNFs) hierarchical heterostructures. As expected, the BiOI/CNFs presented a much higher degradation rate of methyl orange than that of the pure BiOI under visible light. The degradation rate of methyl orange reaches 85% within 210 min. The enhanced photocatalytic activity could be attributed to the fact that conductive CNFs as substrate could effectively improve the separation and transformation of photogenerated charges. Moreover, the fabricated BiOI/CNFs after five cycles could be easily recycled without a decrease in photocatalytic activity due to their ultra-long one-dimensional nano-structural property.

Hierarchical accordion-like manganese oxide@carbon hybrid with strong interaction heterointerface for high-performance aqueous zinc ion batteries.

Aqueous zinc ion batteries have attracted extensive concern as a promising candidate for large-scale energy storage because of their high theoretical specific capacity, low cost and inherent safety. However, the lacking of applicable cathode materials with outstanding electrochemical performance have severely hindered the further development of aqueous zinc ion batteries. Herein, we report a hierarchical accordion-like manganese oxide@carbon (MnO@C) hybrid with strong interaction heterointerface and comprehensively inquire into its electrochemical performance as cathode materials for aqueous zinc ion batteries. The unique hierarchical accordion-like layered structure coupling with strong interaction heterointerface between small MnO and carbon matrix efficaciously improve the ion/electron transfer process and enhance structure stability of the MnO@C hybrid. Benefitting from these unique advantages, the MnO@C hybrid bestows excellent specific capacity of 456mAhg-1 at 50mAg-1. Impressively, the MnO@C hybrid presents distinguished long-term cycling stability with fairly low decay rates of only 0.0079% per cycle even over 2000 cycles at 2000mAg-1. Moreover, comprehensive characterizations are executed to elucidate the mechanism involved. Therefore, this work affords a new idea for developing outstanding performance manganese-based cathode materials for aqueous zinc ion batteries.

Formation of Yolk–Shell MoS2@void@Aluminosilica Microspheres with Enhanced Electrocatalytic Activity for Hydrogen Evolution Reaction

The development of low-cost electrode materials with enhanced activity and favorable durability for hydrogen evolution reactions (HERs) is a great challenge. MoS2 is an effective electrocatalyst with a unique layered structure. In addition, aluminosilica shells can not only provide more hydroxyl groups but also improve the durability of the catalyst as a protective shell. Herein, we have designed a hard-template route to synthesize porous yolk–shell MoS2@void@Aluminosilica microspheres in a NaAlO2 solution. The alkaline solution can directly etch silica (SiO2) hard templates on the surface of MoS2 microspheres and form a porous aluminosilica outer shell. The electrocatalytic results confirm that the MoS2@void@Aluminosilica microspheres exhibit higher electrocatalytic activity for HERs with lower overpotential (104 mV at the current density of −10 mA cm−2) and greater stability than MoS2 microspheres. The superior electrocatalytic activity of MoS2@void@Aluminosilica microspheres is attributed to the unique structure of the yolk@void@shell geometric construction, the protection of the aluminosilica shell, and the greater number of active sites offered by their nanosheet subunits. The design of a unique structure and new protection strategy may set up a new method for preparing other excellent HER electrocatalytic materials.

Confining MoS2–C nanoparticles on two-dimensional graphene sheets for high reversible capacity and long-life potassium ions batteries

Benefiting from the unique layer structure and large interlayer spacing, the transition metal dichalcogenides have been regarded as promising anode materials to host K ions and widely explored in potassium ion batteries (PIBs). However, the low conductivity and large volume variation decline the cycling capacity and stability. It is still challenge to develop high performance anode to storage K+. Herein, the MoS2 nanoparticles anchored onto graphene sheet were synthesized (MoS2–C/rGO) through facile “one-step redox reaction” and following sulfidation method. Impressively, MoS2–C/rGO displayed superb cycling capability with a high reversible capacity of 405.25 mAh/g after 100 cycles at 0.1 A/g, accompanied with remarkable rate performance, outperforming than MoS2–C and MoS2. Most importantly, the ultra-long working life over 2000 cycles with a stable capacity of 161.67 mAh/g at 2 A/g was achieved in MoS2–C/rGO. The two-dimensional structure, rGO sheet and N, P co-doped C matrix of MoS2–C/rGO play great role on providing abundant ions storage sites, increasing conductivity and suppressing volume expansion, leading to high specific capacity, superior rate performance and cycling stability in PIBs. The ex-situ XPS revealed the conversion reaction mechanism for MoS2 during cycling. Accordingly, our work provides a new insight to design alternative anodes for PIBs and is significant to the application of the new generation secondary batteries.

Influence of deposit formation on corrosion at the high-temperature superheater of eucalyptus-fired boiler

ABSTRACT Eucalyptus biomass-fired boilers generally experience severe problems with deposit formation and are expected to suffer from severe superheater corrosion at high temperatures due to the large alkali and chlorine content in eucalyptus biomass. The unique deposition layer structure and corrosion mechanism of eucalyptus-fired boilers are discussed in this paper. It was found that a unique sandwich like cell-membrane structure on the heating surface was formed in eucalyptus biomass-fired boilers. Chlorine acts as a catalyst, circulates the reaction and causes serious corrosion. The oxides at the junction of the corrosion layer and the matrix mainly penetrate along the grain boundary of the matrix, forming a unique network structure. There is obvious internal oxidation and mass transfer along the grain boundary in the matrix of 12Cr2MoWVTiB steel pipe, and no obvious internal oxidation in SA213T91 steel pipe due to its fine and uniform grains.

Rose-like ZnNiCo layered double hydroxide grown on Co3O4 nanowire arrays for high energy density flexible supercapacitors

Ternary double layer hydroxides are considered as potential electrode materials for high-performance supercapacitors due to their unique layered structure and synergistic effect among their active components. However, the poor stability of these materials during the redox reaction seriously hinders their practical application. Therefore, it is of practical significance to design highly efficient and facile strategy to solve these issues. Herein, rose-like CC@Co3O4/ZNC-LDH hierarchical structure nanowire arrays are successfully synthesized on carbon cloth by a two-step hydrothermal method combined with a calcination process. Due to the unique structural design and the synergistic effect between Zn, Ni and Co elements, the prepared CC@Co3O4/ZNC-LDH nanocomposites exhibit excellent electrochemical properties (2084 mF cm−2 at 1 mA cm−2) and ideal capacitance retention (86.5 % after 10,000 cycles). In addition, the ASC device assembled with CC@Co3O4/ZNC-LDH nanocomposites as the positive electrode and activated carbon as the negative electrode can provide an energy density of 41 Wh kg−1 and a corresponding power density of 958 W kg−1 in a voltage window of 0–1.7 V. A multifunctional display can be lit up for more than 25 min by connecting two ASC devices in series. Therefore, the prepared rose-like CC@Co3O4/ZNC-LDH electrode with hierarchical structure should have a satisfactory practical application prospect.

Tuning the d-Band States of Ni-Based Serpentine Materials via Fe3+ Doping for Efficient Oxygen Evolution Reaction.

The serpentine germanate materials are promising oxygen evolution reaction (OER) electrocatalysts due to their unique layered crystal structure and electronic structure. However, the catalytic activities still need to be improved to satisfy the practical applications. Adjusting the d-band center of metal active site to balance the adsorption and desorption of intermediates is considered an effective approach to improve the OER activity. In this work, an element dopant strategy was proposed to optimize the d-band state of Ni3Ge2O5(OH)4 serpentine to improve the OER activity. The density functional theory calculations revealed that Fe3+ doping increased the d-band center of the Ni3Ge2O5(OH)4 serpentine, which optimized the adsorption strength of intermediates on surface Ni and Fe atoms so that the Fe3+ doped Ni3Ge2O5(OH)4 (Ni2.25Fe0.75Ge2O5(OH)4) exhibited much reduced Gibbs free energy changes in the rate-determining step compared with pristine serpentine. Inspired by the theoretical calculations, the NixFe3-xGe2O5(OH)4 nanosheets with different amounts of doped Fe3+ were designed and synthesized. The structural characterizations indicated that Fe3+ was successfully doped into Ni3Ge2O5(OH)4 and replaced the Ni2+. The Fe3+ doped NixFe3-xGe2O5(OH)4 nanosheets showed greatly improved OER activity than Ni3Ge2O5(OH)4 and Fe3Ge2O5(OH)4. Further electrochemical analysis illustrated that Fe3+ doping reduced the adsorptive/formative resistance of intermediates and the charge transfer resistance and facilitated the kinetic process of OER. The in situ Raman spectra indicated that the Fe3+ doped Ni3Ge2O5(OH)4 possesses a more active Ni-O bond than pristine Ni3Ge2O5(OH)4. This work provides an effective strategy to tune the d-band center of serpentines for efficient electrocatalytic OER.

A simple solution combustion method for the synthesis of V2O5 nanostructures for supercapacitor applications

The enhanced power density, long term cycling stability, and fast rate of operation, makes supercapacitors as desirable energy storage devices. Though metal oxides play a significant part in energy storage systems, Vanadium oxides have piqued the interest of electrochemists due to their multi-valency, potential window, unique layer structure, affordability, and plentiful availability. Vanadium pentoxide typically has relatively low specific capacitance due to its weak electrical conductivity and ionic diffusivity. However, these properties can be enhanced by encasing vanadium pentoxide in metal or carbonaceous materials, reducing it to the nanoscale, or changing its shape. On the other hand, the synthetic strategies are mostly essential in raising a compound's specific capacitance. Here, we report the synthesis of vanadium pentoxide nanoparticles using a cost effective solution combustion method. The synthesized material was characterized by X-ray diffraction analysis, UV-Vis Spectroscopy, FT-IR Spectroscopy, Scanning Electron Microscopy, Cyclic voltammetry, Galvanostatic Charge-discharge, and Electrochemical Impedance Spectroscopy. The crystallite size of obtained nanoparticles is 28 nm. The specific capacitance of Vanadium pentoxide nanoparticles is 310 F/g and is calculated at 1 A/g using Galvanostatic Charge-discharge method. The obtained specific capacitance is higher than the existing reports on V2O5 nanoparticles.

Synthesis of Bi4O5I2/Bi5O7I heterojunction at weak acidic solution with preferentially growing facets and high photocatalytic activity

Bismuth-rich oxyiodides are promising photocatalysts owing to their unique layered structures, tunable band potentials and excellent redox ability. It is significant to explore a facile and energy-saving method to prepare BixOyIz-based heterojunction photocatalysts with enhanced photocatalytic performance. In this work, Bi4O5I2/Bi5O7I heterojunction was prepared at room temperature in the existence of thiourea (TU). The addition of TU not only reduced pH value to 6 for the generation of Bi4O5I2/Bi5O7I heterojunction from pH 11 in water, but also improved the photocatalytic performance. The as-prepared Bi4O5I2/Bi5O7I (pH 6) heterojunction exhibited superior photocatalytic activity for the degradation of tetracycline (TC) and malachite green (MG) with degradation efficiency of 89.8% and 98.2% within 120 min of visible light illumination, respectively. And the photocatalytic performance was better than those of Bi4O5I2/BiOI heterojunction obtained in the absence of NaOH (79.2%; 85.8%), pure BiOI synthesized without the addition of TU (pH 6) (81%; 81.4%), and Bi4O5I2/Bi5O7I heterojunction produced at pH 11 in water (38.7%; 85.4%). The enhanced photocatalytic activity of Bi4O5I2/Bi5O7I (pH 6) heterojunction could be attributed to smaller particles with higher specific surface area and high exposure ratio of (001) facet of Bi5O7I and (402) facet of Bi4O5I2.