BiVO4 Film Coupling with CoAl2O4 Nanoparticles for Photoelectrochemical Water Splitting Utilizing Broad Solar Spectrum through p-n Heterojunction, Photothermal, and Cocatalytic Synergism.

Water oxidation is an endothermic and kinetics-sluggish reaction; the research of photoanodes with photothermal and cocatalytic properties is of great significance. Herein, BiVO4/CoAl2O4 film photoanodes were studied for solar water splitting through coupling spinel p-type CoAl2O4 nanoparticles on n-type BiVO4 films. Compared to the BiVO4 photoanode, better performance was observed on the BiVO4/CoAl2O4 photoanode during water oxidation. A photocurrent of 3.47 mA/cm2 was produced on the BiVO4/CoAl2O4 photoanode at 1.23 V vs RHE, which is two-fold to the BiVO4 photoanode (1.70 mA/cm2). Additionally, the BiVO4/CoAl2O4 photoanodes showed an acceptable stability for water oxidation. The BiVO4/CoAl2O4 photoanode being of higher water oxidation performance could be attributed to the presence of p-n heterojunction, cocatalytic, and photothermal effects. In specific, under the excitation of λ < 520 nm light, the holes produced in/on BiVO4 can be transferred to CoAl2O4 owing to the p-n heterojunctions of BiVO4/CoAl2O4. Meanwhile, the temperature on the BiVO4/CoAl2O4 photoanode rises quickly up to ∼53 °C under AM 1.5 G irradiation due to the photothermal property of CoAl2O4 through capturing the 520 < λ < 720 nm light. The temperature rising on the BiVO4/CoAl2O4 photoanode improves the cocatalytic activity of CoAl2O4 and modifies the wettability of BiVO4/CoAl2O4 for effective water oxidation.

Mo modulating the structure of monoclinic vanadium dioxide boosting the aqueous ammonium-ion storage for high-performance supercapacitor.

Supercapacitors (SCs) using ammonium-ion (NH4+) as the charge carrier (NH4+-SCs) have attracted continuous attention and vanadium-based materials are proved to have high-efficient NH4+-storage properties. Monoclinic vanadium dioxide, VO2(B), as an anode material applied to SCs has been rarely reported and modulating its electronic structure for boosted NH4+-storage is full of challenge. In this work, molybdenum-doped VO2(B) (Mo-doped VO2(B)) is designed and synthesize to enhance its NH4+-storage. The introduction of Mo atom into the crystal structure of VO2(B) can modulate its crystal structure and bring in some defects. Experimental results manifest that Mo-doped VO2(B) with 2 % Mo-doping shows the best electrochemical properties. Mo-doped VO2(B) achieves the specific capacitance of 1403 F g-1 (390 mAh g-1) at 0.1 A g-1 and the capacitance retention of about 98 % after 5000 cycle, superior to that of VO2(B) (893 F g-1, 248 mAh g-1 at 0.1 A g-1 and 60 % capacitance retention. The hybrid supercapacitor (HSC) assembled by Mo-doped VO2(B) and active carbon delivers good electrochemical performance with the energy density of 38.6 Wh kg-1 at power density of 208.3 W kg-1. This work proves that the Mo-doping is an efficient strategy for boosted NH4+-storage of VO2(B) and this strategy is like a Chinese idiom "like adding wings to a tiger" to guide the design of electrode materials for high-efficient NH4+-storage.

Mn-Doped M2CdCl4 (M = CH3NH3+, C2H8N+, and C3H10N+) Layered Hybrid Perovskite and Its Flexible Film Based on Simple Mechanochemical Synthesis.

Layered hybrid perovskites show significant advantages in the field of optoelectronics. However, the low quantum efficiency and complex preparation methods limit their applications. In this work, we developed a series of perovskite powders with a two-dimensional (2D) layered structure of organic-inorganic hybrid metal halides M2CdCl4:x%Mn (M = CH3NH3+, C2H8N+, C3H10N+) via facile mechanochemical methods. The prepared manganese Mn-doped MA2CdCl4 produces orange emission at 605 nm under both 254 and 420 nm excitation, which originates from a dual excitation channel competition mechanism, and its excitation channel could be changed with the increase of Mn2+ ion concentration. Typically, MA2CdCl4:20%Mn powder exhibits high photoluminescence quantum yield (PLQY) close to 90% at 605 nm due to the organic amine ions enlarging the Mn-Mn interlayer distances. In addition, we prepared MA2CdCl4:x%Mn@PVA flexible films, which also exhibit good luminescence at 254 nm excitation and were unexpectedly found to have a better response to Cs+, which could be a candidate for anticounterfeiting applications.

Vanadate ion promoting the transformation of α-phase molybdenum trioxide (α-MoO3) to h-phase MoO3 (h-MoO3) for boosted Zn-ion storage.

Molybdenum trioxide (MoO3) has been widely studied in the energy storage field due to its various phase states and unique structural advantages. Among them, lamellar α-phase MoO3 (α-MoO3) and tunnel-like h-phase MoO3 (h-MoO3) have attracted much attention. In this study, we demonstrate that vanadate ion (VO3-) can transform α-MoO3 (a thermodynamically stable phase) to h-MoO3 (a metastable phase) by altering the connection of [MoO6] octahedra configurations. h-MoO3 with VO3- inserted (referred to as h-MoO3-V) as the cathode material for aqueous zinc ion batteries (AZIBs) exhibits excellent Zn2+ storage performances. The improvement in electrochemical properties is attributed to the open tunneling structure of the h-MoO3-V, which offers more active sites for Zn2+ (de)intercalation and diffusion. As expected, the Zn//h-MoO3-V battery delivers specific capacity of 250 mAh·g-1 at 0.1 A·g-1 and rate capability (73% retention from 0.1 to 1 A·g-1, 80 cycles), well exceeding those of Zn//h-MoO3 and Zn//α-MoO3 batteries. This study demonstrates that the tunneling structure of h-MoO3 can be modulated by VO3- to enhance the electrochemical properties for AZIBs. Furthermore, it provides valuable insights for the synthesis, development and future applications of h-MoO3.

Synthesis of V2O5·nH2O nanobelts@polyaniline core-shell structures with highly efficient Zn2+ storage.

Aqueous zinc-ion batteries (AZIBs) are regarded as attractive candidates for next-generation energy storage devices. Among various cathode materials, V2O5·nH2O (VOH) possesses a high theoretical capacity but poor cycle stability due to the susceptibility of its open structure to damage by the quick shuttling of Zn2+. Herein, the structural stability of VOH is directly improved by wrapping polyaniline (PANI) on the VOH nanobelts (VOH@PANI). As a cathode material for AZIBs, the VOH nanobelts@PANI core-shell structures exhibit an outstanding cycle stability of 98% after 2000 cycles at 2 A g-1. The improved conductivity and additional energy storage contribution of the PANI endow VOH@PANI with a specific capacity as high as 440 mAh g-1 at 0.1 A g-1, substantially higher than pure VOH (291 mAh g-1). At the same time, high energy and power densities of 349 Wh kg-1 and 3347 W kg-1 are achieved. This work not only demonstrates that p-type doped PANI coatings on VOH can boost the Zn2+ storage of VOH, but also provides a novel method to enhance cathode materials for high electrochemical performance.

Flexible quasi-solid-state zinc-ion hybrid supercapacitor based on carbon cloths displays ultrahigh areal capacitance.

Over the past few years, the flexible quasi-solid-state zinc-ion hybrid supercapacitors (FQSS ZHSCs) have been found to be ideal for wearable electronics applications due to their high areal capacitance and energy density. The assembly of desirable ZHSCs devices that have promising practical applications is of high importance, whereas it is still challenging to assemble ZHSCs devices. In this study, a ZHSC that exhibited ultrahigh areal capacitance and high stability was developed by using an active carbon cloth (ACC) cathode, which could improve ionic adsorption. The as-obtained ACC cathode had an energy storage mechanism due to the electrical double-layer capacitive behavior of Zn2+, which was accompanied by the dissolution/deposition of Zn4SO4(OH)6·5H2O. The ACC//Zn@ACC ZHSC device exhibited an areal capacitance of 2437 mF cm-2 (81 F cm-3, 203 F g-1 under the mass of ACC with ∼12 mg cm-2) at 1 mA cm-2, an areal energy density of 1.354 mWh cm-2 at 1 mW cm-2, as well as high stability (with an insignificant capacitance decline after 20000 cycles), which was demonstrated to outperform the existing ZHSCs. Furthermore, the assembled flexible device still had competitive capacitance, energy density and service life when integrated into a FQSS ZHSC. When applied in practice, the device could achieve high mechanical flexibility, wearable stability and output. This study can inspire the development of the FQSS ZHSC device to satisfy the demands for wearable energy storage devices with high performance.

Effects of Preparation Methods on the Microstructure and Mechanical Properties of Graphene-Reinforced Alumina Matrix Composites.

Recent years have witnessed a growing research interest in graphene-reinforced alumina matrix composites (Al2O3-G). In this paper, to better achieve the dispersion of graphene in composites, a ball milling method for adding raw materials step by step, called stepwise feeding ball milling, was proposed. The Al2O3-1.0 wt % graphene composites were prepared by this stepwise feeding ball milling and hot pressing. Then, the effects of sintering temperature and sintering pressure on the microstructure and mechanical properties of composites were studied. Results showed that the bending strength, fracture toughness and Vickers hardness of composites increased firstly and then decreased with increasing sintering temperature. The mechanical properties of composites were all at their maximum with the sintering temperature of 1550 °C. For example, the bending strength of composites reached 754.20 MPa, which was much bigger than 478.03 MPa at 1500 °C and 364.01 MPa at 1600 °C. Analysis suggested that the strength of composites was mainly related to the grain size, microflaw size and porosity.

Dual intercalation of inorganics-organics for synergistically tuning the layer spacing of V2O5·nH2O to boost Zn2+ storage for aqueous zinc-ion batteries.

Possessing a 2D zinc-ion transport channel, layered vanadium oxides have become good candidates as cathode materials for aqueous rechargeable zinc-ion batteries (ARZIBs). Tuning the lamellar structure of vanadium oxides to enhance their zinc-ion storage is a great challenge. In the present study, we proposed and investigated a "co-intercalation mechanism" in which Mg2+ and polyaniline (PANI) were simultaneously intercalated into the layers of hydrated V2O5 (MgVOH/PANI) by a one-step hydrothermal method. Inorganic-organic co-intercalation could tune the layer spacing of VOH, and this combination played a synergistic role in enhancing the zinc-ion storage in MgVOH/PANI. It showed an extremely large layer spacing of 14.2 Å, specific capacity of up to 412 mA h g-1 at 0.1 A g-1, and the capacity retention rate could reach 98% after 1000 cycles. PANI itself has a zinc-storage capacity, and Mg2+ intercalated with PANI can improve the conductivity of the material and enhance its stability. Further first-principles calculations clearly revealed the structural changes and improved electrochemical performance of vanadium oxides. This method of inorganic and organic co-regulation of the VOH structure opens a new strategy for tuning the lamellar structure of layered materials to boost their electrochemical performances.

Dynamics and Functional Interplay of Nonhistone Lysine Crotonylome and Ubiquitylome in Vascular Smooth Muscle Cell Phenotypic Remodeling.

Background: The crotonylation of histones is discovered of late as one of the post-translational modifications (PTMs) that can regulate gene expression. However, the function of crotonylation on nonhistone proteins in vascular smooth muscle cells (VSMCs) is unclear. Here, we aim to find the cellular characteristics of crotonylated nonhistone proteins and the cross talk with ubiquitinated proteins in VSMC phenotypic remodeling using the modified omics and proteomic analysis. Methods: We performed the modified omics and proteomic analysis of VSMCs before and after the stimulation with platelet-derived growth factor-BB (PDGF-BB). The crotonylated and ubiquitinated pan-antibody was used to enrich proteins and then subjected to a high-throughput mass spectrometry analysis. The enrichment analysis was performed within differentially modified proteins in regard to GO terms, KEGG, and protein domains. Results: As a result, there were 2,138 crotonylation sites in 534 proteins and 1,359 ubiquitination sites corresponding to 657 proteins. These crotonylated proteins detected after PDGF-BB stimulation might be involved in various vital cellular pathways and carry out important functions in VSMCs. Some of them closely took part in significant physiological processes of VSMC phenotypic remodeling, including glycolysis/gluconeogenesis, vascular smooth muscle contraction, and the PI3K-Akt signaling pathway. Furthermore, the KEGG pathway enrichment analysis showed the involvement of ubiquitinated proteins in the physiological processes of VSMC phenotypic remodeling, including glycolysis/gluconeogenesis, vascular smooth muscle contraction, RAS signaling pathway, or the PI3K-Akt signaling pathway. A cross talk analysis showed that there were 199 sites within the 177 proteins modified by crotonylation and ubiquitination simultaneously. Protein-protein interaction (PPI) network analysis indicated that crotonylated and ubiquitinated proteins play an important role in cellular bioprocess commonly and possibly have a synergistic effect. Conclusion: In summary, our bioinformatics analysis shows that the crotonylation and ubiquitination of nonhistone proteins play an essential role in VSMC phenotypic transformation induced by PDGF-BB stimulation. The cross talk between crotonylation and ubiquitination in glycolysis is possibly a novel mechanism during VSMC phenotypic remodeling.

Engineering Interlayer Space of Vanadium Oxide by Pyridinesulfonic Acid-Assisted Intercalation of Polypyrrole Enables Enhanced Aqueous Zinc-Ion Storage.

By adjusting the structure of vanadium oxides, their electrochemical performances as cathode materials for aqueous rechargeable zinc-ion batteries (ARZIBs) can be improved effectively. Due to the layered structure and high specific capacity of V2O5, many guests (like metal ions and conducting polymers) intercalated and regulated the structure to enhance its electrochemical properties. Polypyrrole (PPy) has attracted people's attention due to its good conductive ability. However, the intercalation of PPy into a lamellar structure of hydrated V2O5 (VOH) has rarely been achieved as a cathode material for ARZIBs. Herein, we developed a pyridinesulfonic acid (PSA)-assisted approach to intercalate PPy into the interplanar spacing of VOH under acidic conditions, and the sample is denoted as VOH-PPy (PSA). The presence of protic acid can improve the electrical conductivity of the polymer and enhance the oxidation of VOH, making the polymerization of pyrrole easier. Furthermore, the nitrogen-containing groups in PSA can interact with vanadium to further expand the layer space of VOH, and the sulfonic groups can facilitate the polymerization of pyrrole. The addition of the PSA results in an ultralarge interlayer spacing of 15.8 Å. VOH-PPy (PSA) delivers an excellent specific capacity of up to 422 mAh·g-1 at 0.1 A·g-1 and a stable cycle performance of 165 mAh·g-1 after 5000 cycles at 10 A·g-1. This work not only realizes PPy expanding the lamellar structure of VOH but also provides feasibility for improving the electrochemical properties of VOH as a cathode material for ARZIBs by intercalating conductive polymers.

Rice-like and rose-like zinc silicates anchored on amorphous carbon derived from natural reed leaves for high-performance supercapacitors.

3D N, S, P-doped rice-like C-Zn4Si2O7(OH)2·H2O (C-ZnSi-N2) and rose-like C-Zn2SiO4 (C-ZnSi-CO2) are derived from reed leaves and used for application in supercapacitors. The as-prepared C-ZnSi architectures with a large number of hierarchical pores and high specific surface area from reed leaves have outstanding electrochemical performance. The obtained C-ZnSi-N2 shows 341 F g-1 at the current density of 0.5 A g-1, while the C-ZnSi-CO2 exhibits 498 F g-1, and both of the C-ZnSi materials significantly retain above 99% of their capacitance after 10 000 cycles. Furthermore, the flexible solid-state asymmetric supercapacitors (ASCs) synthesized from C-ZnSi and activated carbon (denoted as C-ZnSi-N2//AC and C-ZnSi-CO2//AC) achieve a high capacitance (405 and 194 mF cm-2 at the current density of 2 mA cm-2, respectively). Besides, the ASC devices show good cycling stability for 7300 cycles with 73% and 77% capacitance retention. The results presented in this study indicate that the N, S, P-doped C-ZnSi architectures from natural reed leaves are promising and efficient materials for manufacturing high performance supercapacitors.

Polyaniline-expanded the interlayer spacing of hydrated vanadium pentoxide by the interface-intercalation for aqueous rechargeable Zn-ion batteries.

The metal ions or conductive macromolecules intercalated hydrated vanadium oxides for aqueous Zn-ion batteries (AZIBs) have received increasing attention in recent years. The strategy for the preparation of the intercalated hydrated vanadium oxides has been achieved great advances but is still a huge challenge. In this contribution, we develop an interface-intercalation method to synthesize the polyaniline-intercalated hydrated vanadium pentoxide (V2O5·nH2O), denoted as PANI-VOH, as the cathode materials for AZIBs. The prepared PANI-VOH exhibits a 3D sponge-like morphology and the surface area of 190 m2·g-1. The interlayer spacing of VOH is expanded to be 14.1 Å, which provides a lot of channels for the rapidly reversible (de)intercalation of Zn2+ ions. The coin-typed Zn//PANI-VOH battery shows the specific discharge capacity of 363 mAh·g-1 at 0.1 A·g-1 and stable cycling performance. Furthermore, the specific capacity remains 131 mAh·g-1 after 2000 cycles at 5 A·g-1, and the energy density is calculated to be 275 Wh·kg-1 at 78 W·kg-1 on the mass of PANI-VOH. The achieved values are comparable to or even much higher than that of the most state-of-the-art V-based cathode materials for AZIBs. The PANI intercalation can shorten the pathways and facilitate the transports for the migration of ions and electrons. Our finding guides a novel strategy for the intercalation of PANI into the layered materials to adjust their interlayer spacing, which exhibits super ions migration efficiency, as the cathode materials for AZIBs and even other multivalent ions batteries.

Mn2+ as the "spearhead" preventing the trap of Zn2+ in layered Mn2+ inserted hydrated vanadium pentoxide enables high rate capacity.

Vanadium oxides attract much attention and are concerned as one of the most promising cathodes for aqueous zinc-ion batteries (AZIBs) owing to the layered structures. However, their intensive development is limited by the fragile structures and laggard ion-transferring. Herein, Mn2+ inserted hydrated vanadium pentoxide nanobelts/reduced graphene oxide (MnxV2O5·nH2O/rGO, abbreviated as MnVOH/rGO) was prepared by a simple one-pot hydrothermal process, delivering excellent electrochemical properties for AZIBs. The Zn//MnVOH/rGO cell operates well even at changing current densities over 45 cycles, behaving 361 mAh·g-1 at 0.1 A·g-1, 323 mAh·g-1 as the current density gradually increasing to 2 A·g-1 and 350 mAh·g-1 when gradually back to 0.1 A·g-1 (∼97% of initial capacity). Such a superb cycling and rate performance is ascribed to the unique stable structure with the compact electrostatic attraction between Mn2+ and V2O5·nH2O (VOH) laminate. On the one hand, Mn2+ generates electrostatic network with [VO6] polyhedrons and suppresses the following electrostatic trap for the moving Zn2+. On the other hand, rGO improves the conductivity, endowing the high capacity and energy density. The performance of the MnVOH/rGO cathode exceeds most of vanadium-based cathodes applying in AZIBs and paves the way to the ideal energy storage system.

Hydrated vanadium pentoxide/reduced graphene oxide-polyvinyl alcohol (V2O5⋠nH2O/rGO-PVA) film as a binder-free electrode for solid-state Zn-ion batteries.

Recently, solid-state aqueous Zn-ion batteries (ZIBs) have become the most promising wearable storage systems to replace Li-ion batteries owing to their advantages such as high safety and environmental friendliness. However, the critical challenge is to develop stable and robust cathode materials for excellent Zn2+ storage. In this study, a hydrated vanadium pentoxide/reduced graphene oxide-polyvinyl alcohol (V2O5⋅nH2O/rGO-PVA, abbreviated as VOH/rGO-P) film was synthesized as a binder-free cathode for solid-state aqueous ZIBs. The addition of PVA not only increases the layer spacing of VOH and forms a strong hydrogen bond network with GO and water molecules, but also enhances the mechanical properties of the film. As a binder-free cathode for solid-state aqueous ZIBs, the VOH/rGO-P film attains excellent electrochemical capacity as high as 481 mAh∙g-1 at 0.1 A∙g-1. Such a high specific capacity indicates that the VOH/rGO-P film shows great potential for the next generation solid-state aqueous ZIBs.

Fabrication of vanadium sulfide (VS4) wrapped with carbonaceous materials as an enhanced electrode for symmetric supercapacitors.

Exploring electrode materials with excellent electrochemical performance is the key to the development of applications in energy storage and conversion. Herein, three-dimensional (3D) vanadium sulfide/carbon nanotubes/reduced graphene oxide (VS4/CNTs/rGO) composite is synthesized by a simple one-step hydrothermal method. VS4 short nanorods cover the both sides of the rGO sheets, and CNTs distribute at the edge of the composite to form a sandwich-like structure, which effectively prevents the accumulation of rGO. Due to the special 3D hierarchical structure, VS4/CNTs/rGO exhibits a large specific surface area and a rich pore structure, and the addition of CNTs and rGO also improves the electrochemical properties of VS4. At 1 A·g-1, VS4/CNTs/rGO exhibits a capacitance of 497 F·g-1 (1374.0 C·g-1) in the voltage range of -1.4 to 1.4 V, which is much higher than those binary materials including CNTs/rGO, VS4/CNTs and VS4/rGO. The VS4/CNTs/rGO symmetric supercapacitor (SSC) device shows a remarkable electrochemical performance in a large potential window up to 2.2 V. The capacitance of VS4/CNTs/rGO SSC device can reach 1003.5 mF·cm-2 (2207.6 mC·cm-2) at 0.5 mA·cm-2, and it exhibits an energy density of 6.75 Wh·m-2 (72.07 Wh·kg-1) at a power density of 1.38 W·m-2 (14.69 W·kg-1). The high capacitance and energy density of the VS4/CNTs/rGO composite in the high voltage interval make it as the potential energy storage material.

Functional-Group Modification of Kraft Lignin for Enhanced Supercapacitors.

Recent efforts to improve the capacitances of Kraft lignin (KL) in supercapacitors have mainly focused on screening KL substrates, which could either compensate the poor conductivity of KL or directly contribute to the capacitance. However, increasing the pseudocapacitance contributed by KL itself, through hydroquinone/quinone redox cycles, remains a challenge, owing to the roughly fixed content of hydroquinone species in natural KL. In this study, the capacitance of KL is greatly improved by using a functional-group modification strategy in which methoxy groups in KL are selectively converted into phenolic hydroxy groups, which facilitate the formation of additional hydroquinone moieties and thus lead to higher pseudocapacitances. The oxidized KL materials show up to 25.6 % enhancement of the phenolic hydroxy content in comparison to raw KL, which results in 21.9 % capacitance improvement from 322 to 390 F g-1 at 0.5 A g-1 in an acidic system.

Synthesis of amorphous cobalt silicate nanobelts@manganese silicate core-shell structures as enhanced electrode for high-performance hybrid supercapacitors.

Among diverse transition metal silicates (TMSs), cobalt silicate (Co2SiO4) and manganese silicate (MnSiO3) have been diffusely developed for electrode materials due to their high theoretical capacity, structural stability and simple synthetic process. In this work, Co2SiO4 nanobelts@MnSiO3 have been designed and synthesized as the enhanced electrode for high-performance hybrid supercapacitors. The one-dimensional (1D) Co2SiO4 nanobelts enhance their ability to transport electrons along the long axis, which allows current collection during the charge and discharge to improve electrochemical performances. The MnSiO3 coating can be a steady elastic buffer layer, which can protect the active materials during the charge and discharge in effect. What's more, the "core" and "shell" will both be a considerable offering to the total capacity. Sure enough, the capacitance value of Co2SiO4 nanobelts@MnSiO3 can achieve 309 F g-1 at 0.5 A g-1 accompanied by 64% capacitance retention after 10,000 cycles. And the hybrid supercapacitor (HSC) device assembled by Co2SiO4 nanobelts@MnSiO3 and activated carbon (AC) own an excellent capacitance of 384 mF cm-2 at 2 mA cm-2 accompanied by 57% capacitance retention after 2000 cycles. Meanwhile, the Co2SiO4 nanobelts@MnSiO3//AC HSC device's power density (P/W m-2) and energy density (E/Wh m-2) can reach to be 30 W m-2 and 0.77 Wh m-2, respectively. The unique and novel microstructure makes cobalt silicate and manganese silicate shine once again in excellent electrochemical performance.

Ultrathin Ti3C2Tx (MXene) Nanosheet-Wrapped NiSe2 Octahedral Crystal for Enhanced Supercapacitor Performance and Synergetic Electrocatalytic Water Splitting.

Metal selenides, such as NiSe2, have exhibited great potentials as multifunctional materials for energy storage and conversation. However, the utilization of pure NiSe2 as electrode materials is limited by its poor cycling stability, low electrical conductivity, and insufficient electrochemically active sites. To remedy these defects, herein, a novel NiSe2/Ti3C2Tx hybrid with strong interfacial interaction and electrical properties is fabricated, by wrapping NiSe2 octahedral crystal with ultrathin Ti3C2Tx MXene nanosheet. The NiSe2/Ti3C2Tx hybrid exhibits excellent electrochemical performance, with a high specific capacitance of 531.2 F g-1 at 1 A g-1 for supercapacitor, low overpotential of 200 mV at 10 mA g-1, and small Tafel slope of 37.7 mV dec-1 for hydrogen evolution reaction (HER). Furthermore, greater cycling stabilities for NiSe2/Ti3C2Tx hybrid in both supercapacitor and HER have also been achieved. These significant improvements compared with unmodified NiSe2 should be owing to the strong interfacial interaction between NiSe2 octahedral crystal and Ti3C2Tx MXene, which provides enhanced conductivity, fast charge transfer as well as abundant active sites, and highlight the promising potentials in combinations of MXene with metal selenides for multifunctional applications such as energy storage and conversion.

In-situ grown manganese silicate from biomass-derived heteroatom-doped porous carbon for supercapacitors with high performance.

Supercapacitor performance is reported for manganese silicate hybridized carbon materials (MnSi-C) that is derived from natural bamboo leaves. The in-situ generated manganese silicate is in good distribution by a simple hydrothermal treatment without the addition of another controlling agent. We also study the performance of MnSi-C as a single electrode and a cathode for fabrication of asymmetric supercapacitor device with a Ni(OH)2 anode. Remarkably, the single electrode MnSi-C-3 delivered a capacity of 162.2 F g-1 at a current density of 0.5 A g-1. The cyclic performance of single electrode MnSi-C-3 maintains high capacitance retention of 85% after 10,000 cycles of charge-discharge. By assembled MnSi-C-3 with Ni(OH)2, the asymmetric supercapacitor device shows a capacity of 438.5 mF cm-2 at a scan rate of 4 mA cm-2. The device exhibits an optimal electrochemical performance with an energy density of 3 mWh cm-3 (24.6 Wh kg-1) and power density of 130.4 mW cm-3 (604.8 W kg-1). A reasonable mechanism of in-situ generated manganese silicate on the surface of carbon is proposed based on the experimental data and existed theories. This MnSi-C nanocomposite proves to be a promising electrode material for high energy supercapacitor.

Formation and optical properties of metal/10-hydroxybenzo[h]quinolone complexes in the interlayer spaces of magadiite by solid-solid reactions.

Intercalation and in situ formation of three fluorescent complexes, Al(III)-, Cr(III)- and Cu(II)-10-hydroxybenzo[h]quinolone (M-HBQ, M = Al, Cr and Cu), in the interlayer spaces of magadiite (mag) were studied by solid-solid reactions between metal ions exchanged mags (M-mag, M = Al, Cr and Cu) and HBQ. Results show that the basal spacings of the intercalated composites increase after the intercalation of HBQ into M-mags. The amount of HBQ in the intercalated compounds is different due to the amount of metal ions and the diversification of coordination ability of metal ions, and the order of the coordination ability of these three metal ions is Cu2+ > Cr3+ > Al3+. The amount of the metal cations in the interlayer of mag is enough for the in situ complex formation of M-HBQ complexes. The slight shift of the absorption and luminescence bands of the complexes suggests the different microstructures, including molecular packing of the complexes in the interlayer spaces of mags, resulting that the host-guest interactions are formed. These findings show that the intercalation and in situ formation of M-HBQ complexes (M = Al, Cr and Cu) in the interlayer space of mag are successfully achieved in the current work.