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Abstract Ti3C2Tx Quantum dots (QDs)/L‐Ti3C2Tx fiber electrode (Q3M7) with high capacitance and excellent flexibility is prepared by a wet spinning method. The assembled units Ti3C2Tx nanosheets (NSs) with large size (denoted as L‐Ti3C2Tx) is obtained by natural sedimentation screen raw Ti3AlC2, etching, and mechanical delamination. The pillar agent Ti3C2Tx QDs is fabricated by an ultrasound method. Q3M7 fiber electrode gave a specific capacitance of 1560 F cm−3, with a capacity retention rate of 79% at 20 A cm−3, and excellent mechanical strength of 130 Mpa. A wide temperature all‐solid‐state the delaminated montmorillonite (F‐MMT)/Polyvinyl alcohol (PVA) dimethyl sulfoxide (DMSO) flexible hydrogel (DHGE) (F‐MMT/PVA DHGE) Q3M7 fiber supercapacitor is assembled by using Q3M7 fiber as electrodes and F‐MMT/PVA DHGE as electrolyte and separator. It showed a volume specific capacitance of 413 F cm−3 at 0.5 A cm−3, a capacity retention of 97% after 10 000 cycles, an energy density of 36.7 mWh cm−3 at a power density of 311 mW cm−3, and impressive capacitance and flexibility over a wide temperature range of −40 to 60 °C. This work provides an effective strategy for designing and assembling wide temperature all‐solid‐state fiber supercapacitors with optimal balance of capacitive performance and flexibility.

Abstract Photo‐assisted Li–O2 batteries are introduced as a promising strategy for reducing severe overpotential by directly employing photocathodes. Herein, a series of size‐controlled single‐element boron photocatalysts are prepared by the meticulous liquid phase thinning methods by combining probe and water bath sonication, and their bifunctional photocathodes in the photo‐assisted Li–O2 batteries are systematically investigated. The boron‐based Li–O2 batteries have shown incremental round‐trip efficiencies as the sized reduction of boron under illumination. It is noteworthy that the completely amorphous boron nanosheets (B4) photocathode not only delivers an optimizing round‐trip efficiency of 190% on the basis of the ultra‐high discharge voltage (3.55 V) and ultra‐low charge voltage (1.87 V) but also gives a high rate performance and ultralong durability with a round‐trip efficiency of 133% after 100 cycles (200 h) compared with the other‐sized boron photocathodes. This remarkable photoelectric performance of the B4 sample can be attracted to the synergistic effect on the suitable semiconductor property, high conductivity, and strengthened catalytic ability of boron nanosheets coated with ultrathin amorphous boron‐oxides overlayer. This research can open a new avenue to facilitate the rapid development of high‐efficiency photo‐assisted Li–O2 batteries.

Arc volcanism is a key process influencing Earth’s climate, continental growth, and the formation of mineral deposits. Therefore in this contribution, we have compiled whole-rock geochemistry of frontal arc and rear-/back-arc basalts, crustal thickness, and slab parameters (e.g., slab age, slab dip, and convergence velocity) from global convergent margins to investigate the factors controlling along-arc and across-arc variations. Crustal thickness or lithosphere thickness plays a dominant role in elements immobile in aqueous fluids (e.g., Zr/Yb and Nb/Yb). The effect is imposed through mantle partial melting for both frontal arc and rear-/back-arc rocks. Slab thermal structure also affects these immobile elements and gives rise to along-arc variations. Both slab sediment and altered oceanic crust can melt especially in hot subduction zones which yield across-arc variations (e.g., Nd isotope). Aqueous fluids (represented by element ratios such as Ba/Nb and Sr/Nd) also show across-arc variations as they decrease toward rear-/back-arc. This meanwhile decreases mantle wedge melting as rear-/back-arcs show higher Zr/Yb and Nb/Yb. However, no correlations between aqueous fluids and slab parameters suggest aqueous fluids in arc rocks are controlled by complex processes. We summarize factors such as slab alteration, slab dehydration, and mantle metasomatism might impose an effect on the content of fluid mobile elements in arc rocks.

V2O5 is one of the promising cathodes for aqueous zinc ion batteries. However, its performance is largely hindered by its low conductivity and poor cycling stability due to the electrode dissolution. In this work, an interfacial polymerization strategy is developed to prepare the V2O5@poly(3,4-ethylenedioxythiophene) (PEDOT) core-sheath nanowire electrode. The interfacial redox reactions between the vapor 3,4-ethylenedioxythiophene molecules and V2O5 nanowires initiate the polymerization reaction to yield uniform PEDOT sheaths with varying thickness controlled by the reaction duration. The PEDOT sheaths are found to improve the electrode conductivity, suppress the V2O5 nanowire dissolution, and improve the specific capacity. Theoretical simulation further shows that the PEDOT sheath weakens the interactions between Zn2+ and the V2O5 host, thus benefiting the extraction of Zn2+ from the host electrode and boosting the cycling stability. Consequently, V2O5@PEDOT-50m delivers a specific capacity of 293 mA h g-1 at 0.1 A g-1 and 225 mA h g-1 at 1 A g-1, which are superior to 205 mA h g-1 and 142 mA h g-1 of the pristine V2O5 nanowire electrode, respectively. Moreover, V2O5@PEDOT-50m maintains 97.8% and 99% capacity retention after 100 and 2000 cycles, respectively. The significantly enhanced performances with respect to the corresponding V2O5 nanowire counterpart demonstrate that the PEDOT sheaths developed by the interfacial polymerization could become an effective method to stabilize the vanadate-based cathodes for zinc ion storage. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) have attracted increasing interest as promising candidates for large-scale energy storage due to their low cost, natural abundance and similar chemical intercalation mechanism with lithium-ion batteries. However, achieving superior rate capability and long-life for SIBs remains a major challenge owing to the limitation of favorable anode materials selection. Herein, an elegant one-step solvothermal method was used to synthesize VS4 nanorods and VS4 nanorods/reduced graphene oxide (RGO) nanocomposites. The effects of ethylene carbonate/diethyl carbonate(EC/DEC), ethylene carbonate/dimethyl carbonate(EC/DMC), and tetraethylene glycol dimethyl ether (TEGDME) electrolytes on the electrochemical properties of VS4 nanorods were investigated. The VS4 nanorods electrodes exhibit high specific capacity in EC/DMC electrolytes. A theoretical calculation confirms the advance of EC/DMC electrolytes for VS4 nanorods. Significantly, the discharge capacity of VS4/RGO nanocomposites remains 100 mAh/g after 2000 cycles at a large current density of 2 A/g, indicating their excellent cycling stability. The nanocomposites can improve the electronic conductivity and reduce the Na+ diffusion energy barrier, thereby effectively improving the sodium storage performance of the hybrid material. This work offers great potential for exploring promising anode materials for electrochemical applications.

Black phosphorus (BP), especially for BP nanosheets, with unique layered structure among two dimensional (2D) materials has attracted much attention due to its outstanding physical properties, such as ultra-high mobility, in-plane anisotropic properties. However, the small horizontal-size of reported BP limits its applications in the integrated circuit or some functional devices. In this work, a solvothermal-assisted liquid-phase exfoliation technique is firstly employed for preparing large size and high-quality BP nanosheets. In the high-polar acetonitrile solvent, solvothermal treatment weakens the Van der Waals forces of block BP. Together with the subsequently ultrasonic processing, effective exfoliation of large size and high-quality BP nanosheets are realized. The TEM, AFM and Raman results indicate that the prepared BP nanosheets are high quality with an average thickness of about 2 nm, and the horizontal-size is up to 10 μm. This facile and effective method for exfoliated BP nanosheets provides a promising strategy for the exfoliation of other 2D materials. Keywords: Two dimensional materials black phosphorus, Liquid exfoliation, Solvothermal method

Three dimensional ordered graphitized mesoporous carbon GMC-6 (pore diameter ∼6 nm) and GMC-13 (pore diameter ∼13 nm), prepared by a nickel-catalyzed template-assisted method, were explored systematically for the construction of enzyme-based electrochemical biosensors. Comparative studies revealed that GMC-6 offer significant advantages over GMC-13 and graphitized multiwalled carbon nanotubes (CNTs) in facilitating the direct electron transfer of entrapped hemoglobin and improving the performance of fabricated biosensors. The possible factors that affect the biosensing performance of these carbon materials were evaluated comprehensively and comparatively based on the characterization of their physical parameters. The biosensor based on GMC-6 displayed excellent analytical performance over a wide linear range along with good stability and selectivity for the detection of hydrogen peroxide. The “entrapment” immobilization mode and “interspace confinement effect” (by restraining the unfolding or conformational change of enzyme molecules from inactivation) provided by GMC can result in pore-size-dependent enzymatic stability and bioactivity, which might be a crucial factor for the superior biosensing performance of GMC-6 to that of CNTs and GMC-13. Graphitized ordered mesoporous carbons with good pore size matching for enzymes proved to be a promising electrochemical biosensing platform. [ABSTRACT FROM AUTHOR]

In this work, we present a facile route to fabricate three-dimensionally ordered macroporous SiO2/graphitized carbon, TiO2/graphitized carbon, and the resultant graphitic carbon. The graphitized carbons were formed by catalytic graphitization of polystyrene arrays, which were used as both template and carbon source for the generation of macroporous composite. The prepared samples were characterized via powder X-ray diffraction, Raman spectroscopy, SEM, TEM, HRTEM, thermogravimetic analysis, and N2adsorption. The graphitization degree and the content of graphitic carbon in the composite were dependent on the pyrolysis temperature and confinement effect of macroporous oxides skeleton. The composite of SiO2/graphitized carbon exhibited long-range ordered structure at the pyrolysis temperature ranging from 600 to 1000 °C. The low pyrolysis temperature leads to the low degree of graphitization and low content of graphitic carbon in the composite. After the SiO2skeleton was removed, depending on the carbon content and the graphitization extent in the SiO2/graphitized carbon composite, the resultant graphitic carbons display either collapsed or ordered macroporous structure. Based on the HRTEM, the interlayer distance of graphitized carbon at a pyrolysis temperature of 900 °C is estimated to be 0.348 nm. In comparison with SiO2/graphitized carbon, the composite of TiO2/graphitized carbon exhibits less ordering but slightly higher surface area. The photoactivity of TiO2/graphitized carbon was examined and compared to commercial P25 and the composite of TiO2/amorphous carbon in terms of degradation of Rhodamine B and eosin Y aqueous solution. It was found the TiO2/graphitized carbon showed higher activity than TiO2/amorphous carbon and P25 in the degradation of Rhodamine B and activity comparable to that of P25 in the degradation of eosin Y. [ABSTRACT FROM AUTHOR]