Multifunctional Zincophilic Hydrogel Electrolyte with Abundant Hydrogen Bonds for Zinc-Ion Capacitors and Supercapacitors.

The new-generation flexible Zn-ion capacitors (ZICs) require multifunctionality and environmental adaptability for practical applications. This essentially means that hydrogel electrolytes are expected to possess superior mechanical properties, temperature resistance, and tunable interface properties to resist flexibility loss and performance degradation over a wide operating temperatures range. Herein, a multifunctional polyzwitterionic hydrogel electrolyte (PAM/LA/PSBMA) with wide operating temperatures, excellent tensile ability, high water retention, and self-adhesion is designed. Molecular dynamics simulations and experimental results show that polar functional groups (-COO-, -SO3-, -C═O, and -NHCO-) in the hydrogel can form abundant hydrogen bonds with water molecules, which can destroy the original hydrogen bonds (HBs) network between the water molecules and have a low freezing point. It can also form coordination with Zn2+, so that the deposition of Zn2+ electric field homogenization effectively alleviates the growth of Zn dendrites. On this basis, the constructed Zn//Zn cell can be stably cycled 290 h at 10 mA cm-2 (1 mA h cm-2). The constructed ZICs and supercapacitor have a high specific capacitance, excellent energy density, good ionic conductivity, and long cycling stability. This study provides guidance on molecular design for the development of integrated multifunctional smart electronic devices that are environmentally adaptable, resistant to drying, and highly flexible.

Bimetallic iron complex constructed clusters and single atoms neighboring structure to enhance oxygen reduction reaction performance.

Electrocatalysts are useful in lowering the energy barrier in oxygen reduction reaction (ORR). In this study, a catalyst with neighboring Fe single-atom and cluster is created by adsorbing a bimetallic Fe complex onto N-doped carbon and then pyrolyzing it. The resulting catalyst has good performance and a half-wave potential of 0.89 V. When used in Zn-air batteries, the voltage drops by only 8.13 % after 145 h of cycling. Theoretical studies show that electrons transfer from neighboring clusters to single atoms and the catalyst has a lower d-band center. These reduce intermediate desorption energy, hence improving ORR performance. This work demonstrates the capacity to adjust the catalytic properties through the interaction of diverse metal structures, which helps to design more efficient catalysts.

Title High Solar-Thermal Conversion Aerogel for Efficient Atmospheric Water Harvesting.

The shortage of freshwater is a global problem, however, the gel that can be used for atmospheric water harvesting (AWH) in recent years studying, suffer from salt leakage, agglomeration, and slow water evaporation efficiency. Herein, a solar-driven atmospheric water harvesting (SAWH) aerogel is prepared by UV polymerization and freeze-drying technique, using poly(N-isopropylacrylamide) (PNIPAm), hydroxypropyl cellulose (HPC), ethanolamine-decorate LiCl (E-LiCl) and polyaniline (PANI) as raw materials. The PNIPAm and HPC formed aerogel networks makes the E-LiCl stably and efficiently loaded, improving the water adsorption-desorption kinetics, and PANI achieves rapid water vapor evaporation. The aerogel has low density ≈0.12-0.15 g cm-3, but can sustain a weight of 1000 times of its own weight. The synergist of elements and structure gives the aerogel has 0.46-2.95 g g-1 water uptake capability at 30-90% relative humidity, and evaporation rate reaches 1.98 kg m-2 h-1 under 1 sun illumination. In outdoor experiments, 88% of the water is harvesting under natural light irradiation, and an average water harvesting rate of 0.80 gwater gsorbent -1 day-1. Therefore, the aerogel can be used in arid and semi-arid areas to collect water for plants and animals.

Covalent Organic Frameworks as Electrode Materials for Alkali Metal-ion Batteries.

Covalent organic frameworks (COFs) are a class of porous crystalline polymeric materials constructed by linking organic small molecules through covalent bonds. COFs have the advantages of strong covalent bond network, adjustable pore structure, large specific surface area and excellent thermal stability, and have broad application prospects in various fields. Based on these advantages, rational COFs design strategies such as the introduction of active sites, construction of conjugated structures, and carbon material composite, etc. can effectively improve the conductivity and stability of the electrode materials in the field of batteries. This paper introduces the latest research results of high-performance COFs electrode materials in alkali metal-ion batteries (LIBs, SIBs, PIBs and LSBs) and other advanced batteries. The current challenges and future design directions of COFs-based electrode are discussed. It provides useful insights for the design of novel COFs structures and the development of high-performance alkali metal-ion batteries.

Rapid Radiation Synthesis of a Flexible, Self-Healing, and Adhesive Ionogel with Environmental Tolerance for Multifunctional Strain Sensors.

Ionogels are increasingly used in flexible strain sensors, but it is still challenging to incorporate multifunctional properties such as flexibility, self-healing, adhesion, temperature resistance, and electrical conductivity. Herein, a facile and rapid one-step photoinitiated polymerization strategy is employed to prepare multifunctional ionogels by filling a hydrophobic and conductive ionic liquid into a flexible, hydrophobic fluoropolymer matrix. Thanks to the presence of abundant noncovalent interactions (hydrogen-bonding and ion-dipole interactions), the ionogels exhibit high transparency, excellent mechanical properties, self-healing ability, and adhesion. Moreover, rich C-F bonds in the fluoropolymer matrix can eliminate the interference of water molecules, resulting in excellent environmental tolerance such as high and low temperature resistance, waterproofness, and anticorrosion. Furthermore, the ionogel-based wearable strain sensor can sensitively detect and differentiate human movements and subtle muscle movements and serve as a Morse code signal transmitter for information transmission. The presented work provides an effective method to develop versatile flexible conductive ionogels for wearable devices and ionotronics.

Alleviating Zn Dendrites by Growth of Ultrafine ZnO Nanowire Arrays through Horizontal Anodizing for High-Capacity, Long-Life Zn Ion Capacitors.

Zn ion capacitors (ZICs) composed of a carbon-based cathode and a Zn anode are one of the most promising energy storage devices due to their inherent safety and high-power output. However, their poor cycling stability originating from the Zn dendrites' formation and low energy density limited by insufficient activated carbon properties remain major challenges for development of high-performance ZICs. Hence, we constructed a facile and effective strategy to alleviate "edge effects" and suppress Zn dendrites by growing ZnO nanowire arrays on Zn foil (ZnO@Zn) using a horizontally potentiostatic anodizing technique. The electrochemical characterizations and in situ optical microscopy observation revealed that the introduction of ZnO nanowire arrays can significantly suppress the growth of Zn dendrites and enhance the cycling stability of the Zn anode. The superfine and interlaced ZnO nanowire arrays provide uniform nucleation sites and high electrical conductivity for the Zn metal anode, reducing the local current density and promoting the rapid diffusion and migration of Zn ions on the Zn anode surface. As a result, the ZnO@Zn electrode has a very low nucleation overpotential and excellent cycle stability, far superior to the bare Zn anode. Furthermore, a ZnO@Zn//NPHC ZIC assembled with an N, P-codoped hard carbon (NPHC) cathode delivers a high specific capacity of 110.3 mAh g-1 at 0.1 A g-1 and achieves outstanding cycling stability with 90% capacity retention together with ∼100% Coulombic efficiency after 20000 cycles.

Iron-modulated Ni3S2 derived from a Ni-MOF-based Prussian blue analogue for a highly efficient oxygen evolution reaction.

Developing efficient, environmentally friendly and cost-effective non-precious metal electrocatalysts for the oxygen evolution reaction (OER) is essential to alleviate the energy crisis and environmental pollution. Herein, we report a simple and practical method to prepare non-precious metal catalysts, namely iron-modulated Ni3S2 (Fe-Ni3S2/NF) on nickel foam, by growing a Ni-MOF directly on 3D porous conductive nickel foam, followed by the formation of Ni-MOF-based Prussian blue analogs (Ni-MOF@PBA) via in situ cation exchange reactions, which are further sulfidated to iron-modulated Ni3S2. Based on a series of characterization results, it is confirmed that iron acts as a modulator at the Ni active site, leading to electron depletion, thereby modulating the electron spin state and optimizing the binding energy of key reaction intermediates, resulting in highly exposed active sites and acceleration of OER reaction kinetics. The synthesized Fe-Ni3S2/NF exhibits excellent activity in alkaline media, which needs overpotentials of only 232 mV and 287 mV to drive current densities of 10 mA cm-2 and 50 mA cm-2, respectively. Additionally, Fe-Ni3S2/NF exhibits excellent stability for at least 24 h during the OER process. This work presents a rational design and synthesis of transition metal-based catalysts with nanocone structures, providing a new strategy for assembling advanced materials and insights for exploring various energy storage and conversion systems.

Three-dimensional nanoporous activated carbon electrode derived from acacia wood for high-performance supercapacitor.

Herein, the novel acacia wood based hierarchical porous activated carbons (AWCs) are easily prepared, low cost and have excellent characterization, such as special biomass nanopores via structural stability and large specific surface areas. Activating agents such as KOH, ZnCl2, and H3PO4 have been used to convert acacia wood carbon into active carbons such as AWC-K, AWC-Z, and AWC-P, respectively, which are named after the activating agent. As a supercapacitor electrode, the AWC-K sample has a high yield was 69.8%, significant specific surface area of 1563.43 m2g-1 and layer thickness of 4.6 mm. Besides that, it showed specific capacitance of 224.92 F g-1 at 0.5 A g-1 in 2 M KOH as electrolyte. In addition, the AWC-K//AWC-K symmetrical supercapacitor device displays high energy density of 23.98 Wh kg-1 at 450 W kg-1 power density with excellent cycling number stability was 93.2% long lifetime of 10,000 cycles using 0.5 M Na2SO4 as electrolyte. The high electrochemistry performance mainly contributed the special biomass pores structure. Therefore, the presented approach opens new avenues in supercapacitor applications to meet energy storage.

An Olefin-based, Fluorescent Covalent Organic Framework for Selective Sensing of Aromatic Amines.

Owing to various chemical structures and different basicity of amines, a fluorescent probe that could distinguish aromatic and aliphatic amines is highly desirable for practical applications. Herein, an olefin-based, fluorescent COF (COF-Py-AN) with unique π-electron deficient groups was synthesized, which was a functionalized platform to realize sensing of π electron-rich aromatic amines. COF-Py-AN displayed fluorescence quenching in the presence of aromatic amines like aniline, with excellent selectivity against a variety of aromatic molecules, and the detection limit of COF-Py-AN toward aniline was as low as 1.29 µM. More importantly, COF-Py-AN could realize discriminating between aromatic and aliphatic amines. Furthermore, density functional theory calculations showed that the photoinduced electron transfer mechanism contributes to fluorescence sensing. This is the first example of olefin-based fluorescent COF materials for selective sensing of aromatic amines.

An asymmetric supercapacitor based on controllable WO3 nanorod bundle and alfalfa-derived porous carbon.

A novel asymmetric supercapacitor (ASC) is assembled on the basis of an inerratic hexagonal-like WO3 nanorod bundle as a negative electrode and graphene-like alfalfa-derived porous activated carbon (APAC) as the positive electrode in 1 M H2SO4 aqueous electrolyte. The WO3 nanostructures prepared at pH of 1.6, 1.8, 2.0, 2.5 and 3.0 display hexagonal disc-like, nanorod bundle, inerratic hexagonal-like, sphere-like, and needle-shaped nanorod morphology. WO3-2.0, which was prepared at a pH of 2.0, exhibits high specific capacitance (415.3 F g-1 at 0.5 A g-1). APAC-2, which had the mass ratios of dried alfalfa and ZnCl2 as 1 : 2, showed a 3D porous structure, large surface area (1576.3 m2 g-1), high specific capacitance (262.1 F g-1 at 0.5 A g-1), good cycling stability with 96% of initial specific capacitance after 5000 consecutive cycles. The ASC assembled with WO3-2.0 and APAC-2 exhibits high energy density (27.3 W h kg-1 at a power density of 403.1 W kg-1), as well as good electrochemical stability (82.6% capacitance retention after 5000 cycles). Such outstanding electrochemical behavior implies that the electrode materials are promising for practical energy-storage systems.

Iron ion irradiated Bi2Te3 nanosheets with defects and regulated hydrophilicity to enhance the hydrogen evolution reaction.

The introduction of defects can enhance the active sites on transition metal dichalcogenides, which can cause changes in crystal structures, and then lead to a change in the original catalytic performance. Herein, an efficient method of introducing defects was reported. In this method, high-energy iron ions were irradiated on the surface of Bi2Te3 nanosheets by ion irradiation technology, which resulted in the generation of a variety of defects. Compared to the original Bi2Te3 nanosheets, the Bi2Te3 nanosheets irradiated by iron ions showed significant improvement in the hydrogen evolution reaction performance in acidic solution. After the iron ion irradiation, the electric double layer capacitance of the Bi2Te3 nanosheets increased significantly, which indicated an increase in the number of active sites on the surface of Bi2Te3. Analysis of high-resolution transmission electron microscopy images reveals the occurrence of various defects on the surface of Bi2Te3 after the iron ion irradiation, which increased the active sites. Moreover, the conductivity of the iron ion-irradiated Bi2Te3 nanosheets was also significantly improved. It is noteworthy that iron ion irradiation changed the characteristic of the Bi2Te3 surface from hydrophobic to hydrophilic, which facilitated the release of hydrogen bubbles from the catalyst surface and exposed the active sites in time. At the same time, the damage caused by the large bubbles to the electrode material could be avoided, and the stability of the material was improved. This efficient iron ion irradiation method provides an innovative idea for the design of other high-efficient catalysts.

Phosphorus-doped CoTe2/C nanoparticles create new Co-P active sites to promote the hydrogen evolution reaction.

Doping has been widely recognized as an effective method for adjusting the performance of electrocatalysts. It can cause changes in the electronic structure of substances. Thereby, it can affect the intrinsic catalytic performance. Herein, we report a facile doping method in which phosphorus can be simultaneously doped into both CoTe2 and C. In the acidic solution, the hydrogen evolution reaction (HER) performance of the obtained P-CoTe2/C nanoparticles was significantly improved compared with that of undoped nanoparticles. At a current density of 10 mA cm-2, the overpotential decreased from 430 mV to 159 mV. Density functional theory (DFT) calculations show that phosphorus doping can produce new high activity Co-P catalytic sites. In addition, phosphorus can be doped into the carbon in the composite at the same time, which enhances the electrical conductivity of the composite. Moreover, in the process of calcination and doping, the electric double layer capacitance (Cdl) of the composite is significantly increased, which helps in exposing more active sites. This work has developed a multi-effect doping method that simultaneously increases the intrinsic activity, conductivity and active sites of the material. This method provides a new strategy for the performance regulation of other electrocatalysts.

Synthesis of porous carbon material based on biomass derived from hibiscus sabdariffa fruits as active electrodes for high-performance symmetric supercapacitors.

Carbon-based materials are manufactured as high-performance electrodes using biomass waste in the renewable energy storage field. Herein, four types of hierarchical porous activated carbon using hibiscus sabdariffa fruits (HBFs) as a low-cost biomass precursor are synthesized through carbonization and activation. NH4Cl is used as a chemical blowing agent to form carbon nanosheets, which are the first types of hibiscus sabdariffa fruit-based carbon (HBFC-1) sample, and KOH also forms a significant bond in the activation process. The prepared HBFC-1 is chosen to manufacture the symmetric supercapacitor due to its rough surface and high surface area (1720.46 m2 g-1), making it show a high specific capacity of 194.50 F g-1 at a current density of 0.5 A g-1 in a three-electrode system. Moreover, the HBFC-1 based symmetric supercapacitor devices display a high energy density of 13.10 W h kg-1 at a power density of 225.00 W kg-1, and a high specific capacity of 29 F g-1 at 0.5 A g-1. Additionally, excellent cycle life is observed (about 96% of capacitance retained after 5000 cycles). Therefore, biomass waste, especially hibiscus sabdariffa fruit based porous carbon, can be used as the electrode for high-performance supercapacitor devices.

Template-Confined Growth of Poly(4-aminodiphenylamine) Nanosheets as Positive Electrode toward Superlong-Life Asymmetric Supercapacitor.

Two-dimensional conducting polymers nanosheet prepared by the soft-template-assisted technique in aqueous system still has rarely been reported, especially the formation of nanosheets structure by protonic acid assisted controlling the stability of the micelles method. Herein, a facile, one-step, bottom-up approach is developed to synthesize novel and uniform conductive poly(4-aminodiphenylamine) (P(4-ADPA)) nanosheets with controlled morphology via regulating the proton acid concentration during the self-assembly of surfactant lamellar micelles. The as-produced conducting P(4-ADPA) demonstrates a integral nanoframework structure with uniform and intertwined nanosheets, resulting in a satisfactory specific capacitance of 395 F g-1 at the current density of 0.5 A g-1. Furthermore, another pseudocapacitor electrode material, urchin-like W18O49, is selected as a negative electrode material to fabricate a novel P(4-ADPA)//W18O49 asymmetric supercapacitor, which extends the operating voltage window up to 1.5 V, provides an energy density of 24.4 W h kg-1 at a high power density of 1491 W kg-1, and possesses superlong-life of 92% capacitance retention after 10 000 cycles. Therefore, the present work will propose an affordable strategy to design novel conducting polymer nanosheets and open up the possibility of cheap conductive polymers to meet the demands of energy storage.

Nanostructure selenium compounds as pseudocapacitive electrodes for high-performance asymmetric supercapacitor.

The electrochemical performance of an energy conversion and storage device like the supercapacitor mainly depends on the microstructure and morphology of the electrodes. In this paper, to improve the capacitance performance of the supercapacitor, the all-pseudocapacitive electrodes of lamella-like Bi18SeO29/BiSe as the negative electrode and flower-like Co0.85Se nanosheets as the positive electrode are synthesized by using a facile low-temperature one-step hydrothermal method. The microstructures and morphology of the electrode materials are carefully characterized, and the capacitance performances are also tested. The Bi18SeO29/BiSe and Co0.85Se have high specific capacitance (471.3 F g-1 and 255 F g-1 at 0.5 A g-1), high conductivity, outstanding cycling stability, as well as good rate capability. The assembled asymmetric supercapacitor completely based on the pseudocapacitive electrodes exhibits outstanding cycling stability (about 93% capacitance retention after 5000 cycles). Moreover, the devices exhibit high energy density of 24.2 Wh kg-1 at a power density of 871.2 W kg-1 in the voltage window of 0-1.6 V with 2 M KOH solution.

Sb2O3 Nanoparticles Anchored on Graphene Sheets via Alcohol Dissolution-Reprecipitation Method for Excellent Lithium-Storage Properties.

Sb2O3 nanoparticles are uniformly anchored on reduced graphene oxide (rGO) sheets via a facile and ecofriendly route based on the alcohol dissolution-reprecipitation method. Such obtained Sb2O3/rGO composite demonstrates a highly reversible specific capacity (1355 mA h g-1 at 100 mA g-1), good rate capability, and superior life cycle (525 mA h g-1 after 700 cycles at 600 mA g-1) when used an anode electrode for lithium-ion batteries (LIBs). The outstanding electrochemical properties of Sb2O3/rGO composite could be attributed to its unique structure in which the strong electronic coupling effect between Sb2O3 and rGO leads to an enhanced electronic conductivity, structure stability, and electrochemical activity during reversible conversion-alloying reactions. Also, these findings are helpful in both developing novel high-performance electrodes for LIBs and synthesizing functional materials in an ecofriendly and economical way.

Ni0.85Se@MoSe2 Nanosheet Arrays as the Electrode for High-Performance Supercapacitors.

In this study, we report novel Ni0.85Se@MoSe2 nanosheet arrays prepared by a facile one-step hydrothermal method through nickel (Ni) foam as Ni precursor and the framework of MoSe2. Owing to the unique interconnection and hierarchical porous nanosheet array architecture, the Ni0.85Se@MoSe2 nanosheet arrays exhibit a high specific capacitance of 774 F g-1 at the current density of 1 A g-1, which is almost 2 times higher than that (401 F g-1) of the Ni0.85Se matrix and about 7 times greater than that (113 F g-1) of the MoSe2 nanoparticles. Moreover, we report an asymmetric supercapacitor (ASC), which is fabricated by using the Ni0.85Se@MoSe2 nanosheet arrays as the positive electrode and the graphene nanosheets (GNS) as the negative electrode, with aqueous KOH as the electrolyte. The Ni0.85Se@MoSe2//GNS ASC possesses an output voltage of 1.6 V, an energy density of 25.5 Wh kg-1 at a power density of 420 W kg-1, and a cycling stability of 88% capacitance retention after 5000 cycles. These results indicate that the Ni0.85Se@MoSe2 nanosheet arrays are a good electrode for supercapacitors.

Anchoring Sb6O13 Nanocrystals on Graphene Sheets for Enhanced Lithium Storage.

Sb6O13/reduced graphene oxide (Sb6O13/rGO) nanocomposite was synthesized by the solvothermal method using Sb2O3 and graphene oxide as raw material. On the basis of the physical and electrochemical characterizations, Sb6O13 nanocrystals of 10-20 nm size were uniformly anchored on rGO sheets, and the nanocomposite displayed a large reversible specific capacity of 1271 mA h g-1 and an excellent cyclability of 1090 mA h g-1 after 140 cycles at 100 mA g-1 when proposed as a potential anode material for lithium ion batteries, emphasizing the advantages of anchoring of Sb6O13 nanocrystals on rGO sheets for the maximum utilization of electrochemically active Sb6O13 and rGO for lithium storage.

Nitrogen-doped porous carbon derived from biomass waste for high-performance supercapacitor.

High capacitance property and low cost are the pivotal requirements for practical application of supercapacitor. In this paper, a low cost and high capacitance property nitrogen-doped porous carbon with high specific capacitance is prepared. The as-prepared nitrogen-doped porous carbon employing potato waste residue (PWR) as the carbon source, zinc chloride (ZnCl2) as the activating agent and melamine as nitrogen doping agent. The morphology and structure of the carbon materials are studied by scanning electron microscopy (SEM), N2 adsorption/desorption, X-ray diffraction (XRD) and Raman spectra. The surface area of the nitrogen-doped carbon which prepared under 700°C is found to be 1052m(2)/g, and the specific capacitance as high as 255Fg(-1) in 2M KOH electrolyte is obtained utilize the carbon as electrode materials. The electrode materials also show excellent cyclability with 93.7% coulombic efficiency at 5Ag(-1) current density of for 5000cycles.

Formation of carbon nanosheets via simultaneous activation and catalytic carbonization of macroporous anion-exchange resin for supercapacitors application.

Two-dimensional mesoporous carbon nanosheets (CNSs) have been prepared via simultaneous activation and catalytic carbonization route using macroporous anion-exchange resin (AER) as carbon precursor and ZnCl2 and FeCl3 as activating agent and catalyst, respectively. The iron catalyst in the skeleton of the AER may lead to carburization to form a sheetlike structure during the carbonization process. The obtained CNSs have a large number of mesopores, a maximum specific surface area of 1764.9 m(2) g(-1), and large pore volume of 1.38 cm(3) g(-1). As an electrode material for supercapacitors application, the CNSs electrode possesses a large specific capacitance of 283 F g(-1) at 0.5 A g(-1) and excellent rate capability (64% retention ratio even at 50 A g(-1)) in 6 mol L(-1) KOH. Furthermore, CNSs symmetric supercapacitor exhibits specific energies of 17.2 W h kg(-1) at a power density of 224 W kg(-1) operated in the voltage range of 0-1.8 V in 0.5 mol L(-1) Na2SO4 aqueous electrolyte, and outstanding cyclability (retains about 96% initial capacitance after 5000 cycles).