Xianluo Hu

Flexible and Binder‐Free Electrodes of Sb/rGO and Na3V2(PO4)3/rGO Nanocomposites for Sodium‐Ion Batteries

Flexible power sources have shown great promise in next-generation bendable, implantable, and wearable electronic systems. Here, flexible and binder-free electrodes of Na3V2(PO4)3/reduced graphene oxide (NVP/rGO) and Sb/rGO nanocomposites for sodium-ion batteries are reported. The Sb/rGO and NVP/rGO paper electrodes with high flexibility and tailorability can be easily fabricated. Sb and NVP nanoparticles are embedded homogenously in the interconnected framework of rGO nanosheets, which provides structurally stable hosts for Na-ion intercalation and deintercalation. The NVP/rGO paper-like cathode delivers a reversible capacity of 113 mAh g(-1) at 100 mA g(-1) and high capacity retention of ≈96.6% after 120 cycles. The Sb/rGO paper-like anode gives a highly reversible capacity of 612 mAh g(-1) at 100 mA g(-1) , an excellent rate capacity up to 30 C, and a good cycle performance. Moreover, the sodium-ion full cell of NVP/rGO//Sb/rGO has been fabricated, delivering a highly reversible capacity of ≈400 mAh g(-1) at a current density of 100 mA g(-1) after 100 charge/discharge cycles. This work may provide promising electrode candidates for developing next-generation energy-storage devices with high capacity and long cycle life.

Flexible fiber-shaped supercapacitors based on hierarchically nanostructured composite electrodes

A novel all-solid-state, coaxial, fiber-shaped asymmetric supercapacitor has been fabricated by wrapping a conducting carbon paper on a MnO2-modified nanoporous gold wire. This energy wire exhibits high capacitance of 12 mF·cm−2 and energy density of 5.4 μW·h·cm−2 with excellent cycling stability. Hierarchical nanostructures and coaxial architectural design facilitate effective contacts between the two core@sheath electrodes and active layers with high flexibility and high performance. This work provides the first example of coaxial fibershaped asymmetric supercapacitors with an operation voltage of 1.8 V, and holds great potential for future flexible electronic devices.

Constructing Hierarchical Tectorum‐like α‐Fe2O3/PPy Nanoarrays on Carbon Cloth for Solid‐State Asymmetric Supercapacitors

The design of complex heterostructured electrode materials that deliver superior electrochemical performances to their individual counterparts has stimulated intensive research on configuring supercapacitors with high energy and power densities. Herein we fabricate hierarchical tectorum-like α-Fe2 O3 /polypyrrole (PPy) nanoarrays (T-Fe2 O3 /PPy NAs). The 3D, and interconnected T-Fe2 O3 /PPy NAs are successfully grown on conductive carbon cloth through an easy self-sacrificing template and inu2005situ vapor-phase polymerization route under mild conditions. The electrode made of the T-Fe2 O3 /PPy NAs exhibits a high areal capacitance of 382.4u2005mFu2009cm-2 at a current density of 0.5u2005mAu2009cm-2 and excellent reversibility. The solid-state asymmetric supercapacitor consisting of T-Fe2 O3 /PPy NAs and MnO2 electrodes achieves a high energy density of 0.22u2005mWhu2009cm-3 at a power density of 165.6u2005mWu2009cm-3 .

TiO2–B Nanosheets/Anatase Nanocrystals Co‐Anchored on Nanoporous Graphene: In Situ Reduction–Hydrolysis Synthesis and Their Superior Rate Performance as an Anode Material

A unique hybrid, TiO2-B nanosheets/anatase nanocrystals co-anchored on nanoporous graphene sheets, can be synthesized by a facile microwave-induced in situ reduction-hydrolysis route. The as-formed nanohybrid has a hierarchically porous structure, involving both mesopores of approximately 4u2005nm and meso-/macropores of 30-60u2005nm in the graphene sheets, and a large surface area. Importantly, electrodes composed of the nanohybrid exhibit superior rate capability (160u2005mAu2009hu2009g(-1) at ca. 36u2009C; 154u2005mAu2009hu2009g(-1) at ca. 72u2009C) and excellent cyclability. The synergistic effects of conductive graphene with numerous nanopores and the pseudocapacitive effect of ultrafine TiO2-B nanosheets and anatase nanocrystals endow the hybrid a superior rate capability.

Nanostructured Ti-based anode materials for Na-ion batteries

With the shortage of fossil energy and global climate change, renewable energy sources offer the most promising solutions to these challenges. However, the intermittence of energy sources such as solar and wind requires sustainable energy storage technologies. Nowadays, electrochemical energy storage technologies and applications have attracted much attention, including portable electric devices, electric vehicles and smart power grids. Lithium-ion batteries (LIBs) have been widely applied in these areas because of their safety, portability and high energy density. Nevertheless, the resources of lithium are limited and the vast consumption of lithium has pushed up the price of lithium compounds, urging people to search for resourceful materials. Sodium can be a promising alternative due to its high abundance and low cost. Furthermore, titanium-based materials have become a hot spot for anode materials in sodium-ion batteries (SIBs), with their advantages of high safety and structural stability. In this review, we summarize the recent advances in Ti-based anode materials for SIB applications. We highlight the design and engineering of Ti-based nanoarchitectures, especially emphasizing the effective enhancement in performance and the related sodium storage mechanism.

Architectural design and phase engineering of N/B-codoped TiO2(B)/anatase nanotube assemblies for high-rate and long-life lithium storage

TiO2 polymorphs hold great promise as anode candidates in lithium-ion batteries (LIBs) because of their low cost, enhanced safety and high power capability, but they suffer from poor electrical conductivity and low lithium-ion mobility. Herein, an attractive nanoassembly made of ultrathin TiO2 nanotubes with selected phases and hetero-atom doping was developed through a mild ionothermal reaction. The grain interface of TiO2(B)/anatase, N/B codoping, and nanoassembly were elaborately engineered. They offer effective nanohighways for fast electronic and Li-ion transport, when applied as an anode in LIBs. The carbon-free, N/B-codoped TiO2(B)/anatase nanotube nanoassemblies exhibit exceptionally high rate capability and good durability (160 mA h g−1 at 12 A g−1 and retaining 140 mA h g−1 even after 500 cycles). This work demonstrates that the integrated design of surface states and electronic structures plays a crucial role in exploring new capabilities of TiO2 polymorphs for electrochemical energy storage.

Biomaterial-assisted synthesis of AgCl@Ag concave cubes with efficient visible-light-driven photocatalytic activity

A facile biomaterial-assisted method has been developed to fabricate AgCl@Ag concave cubes. The biomaterial agar gel was used to moderate the reaction process by providing a reaction matrix to mediate the diffusion of reactants and confine the growth of AgCl@Ag concave cubes. The whole reaction process was performed under mild conditions without heat treatment or organic additives. The as-formed AgCl@Ag concave cubes as a photocatalyst exhibit effective activity for photocatalytic degradation of methyl orange (MO) under visible-light irradiation, which is mainly attributed to the surface plasmon resonance (SPR) of Ag nanoparticles.

Controlled synthesis of monodispersed hematite microcubes and their properties

Hematite (α-Fe2O3) is a thermodynamically stable crystallographic phase of iron oxide and has attractive applications in many areas. By using a simple hydrothermal method, we synthesized smooth hematite microcubes and porous hematite microcubes. The as-synthesized microcubes have uniform edge lengths of about 1 μm. The magnetic, electrochemical properties and gas sensing performance to some organic gases were investigated, revealing the potential applications in various fields. By tuning the experimental parameters, such as source and solvent, we are able to tunably produce goethite (FeOOH) nanowires, and hematite nanoparticles, nanorods, and nanoplatelets and the formation mechanism was also discussed.

Large-scale synthesis of WOx–EDA nanobelts and their application as photoswitches

Hybrid inorganic–organic WOx–EDA nanobelts were prepared in a large scale by a mild solvothermal process. The nanobelts are ∼50 nm wide with lengths up to several tens of micrometres. A photoconduction device made of the resulting hybrid WOx–EDA nanobelts may have potential application as a photoswitch.

Microwave-Assisted Rapid Synthesis of Self-Assembled T-Nb2O5 Nanowires for High-Energy Hybrid Supercapacitors

Recently ion-intercalation hybrid supercapacitors, with high energy density at high power density, have been widely investigated to meet ever-increasing practical demands. Here, a unique hybrid supercapacitor has been designed and fabricated using self-assembled orthorhombic-phase niobium oxide@carbon (T-Nb2 O5 @C) nanowires as an anode and commercially available activated carbon as a cathode. The 3D-interconnected T-Nb2 O5 @C nanowires have been synthesized through a highly efficient microwave-solvothermal method, combined with subsequent thermal treatment. The experimental parameters (e.g., time and temperature) can be easily programmed, and the synthesis time can be significantly shortened, thus enabling the buildup of abundant recipes for the engineering of scaled-up production. The Li-ion intercalation pseudocapacitance electrode, made from the as-formed self-assembled T-Nb2 O5 @C nanowires, shows excellent charge storage and transfer capability. When assembled into a hybrid supercapacitor with a cathode of activated carbon, a high energy density of 60.6u2005Whu2009kg-1 and a high power density of 8.5u2005kWu2009kg-1 with outstanding stability are achieved. In virtue of easy optimization and programmability of the synthetic strategy, and the remarkable electrochemical performance, the self-assembled T-Nb2 O5 @C nanowires offer a promising anode for asymmetric hybrid supercapacitors.