Heterogeneous ice nucleation of salt solution in porous media.

Water ubiquitously exists with dissolved salt in both natural and engineered porous media, such as soil, rock, concrete, and tissue; therefore, its freezing temperature depression behavior is of particular interest to various scientific communities tackling with mechanics and physics of porous media. To date, it remains elusive which physical mechanism accounts for its freezing temperature depression and how dissolved ions affect it. Herein, a series of pore-scale experiments were designated to investigate the freezing temperature of salt solutions in tubes with varying pore diameters, pore solution volumes, solid-liquid interfacial areas, ion concentrations, and ion types. The results reveal two main findings: (i) the freezing temperature depression of pore solutions is governed by the heterogeneous ice nucleation (HIN) at the water-solid interface, as evidenced by the observation that the freezing temperature decreases with the decreasing solid-liquid interfacial areas, regardless of pore diameter and pore solution volume; (ii) the dissolved salts alter HIN processes via changing the osmotic potential across the ice embryo-liquid water interface, as indicated by the observation that the freezing temperature is mainly determined by the salt concentration irrespective of salt types. Furthermore, the classical nucleation theory model is adapted for the freezing behavior of pore solutions by including an osmotic potential term. The model shows excellent performance in capturing experimental data with various pore solution concentrations, further substantiating the HIN as the physical mechanism governing pore solution freezing.

Steerable artificial magnetic bacteria with target delivery ability of calcium carbonate for soil improvement.

The microbial-induced carbonate precipitation (MICP) has acquired significant attention due to its immense potential in sustainable engineering applications, particularly in soil improvement. However, the precise control of microbial-induced calcium carbonate precipitation remains a formidable challenge in engineering practices, owing to the uncertain movement paths of bacteria and the nonuniform distribution of soil pores. Taking inspiration from targeted therapy in medicine, this paper presents novel research on the development and validation of magnetically responsive bacteria. These bacteria demonstrate the ability to target calcium carbonate precipitation in a microfluidic chip, thereby promoting an environmentally friendly and ecologically sustainable biomineralization paradigm. The study focuses on investigating the migration of magnetite nanoparticles (MNPs) in aqueous solutions and enhancing the stability of MNP culture liquids. A specially designed microfluidic chip is utilized to simulate natural sand particles and their pores, while an external magnetic field is applied to precisely control the movement path of the artificial magnetic bacteria, enabling targeted precipitation of calcium carbonate at the micron-scale. Verification of the engineered artificial magnetic bacteria and their ability to induce calcium carbonate precipitation is conducted through SEM-EDS analysis, microfluidic chip observations, and the application of the K-means algorithm and ImageJ software to analyze calcium carbonate formation. The influence of the concentration of magnetic nanoparticles on the calcium carbonate production rate was also studied. The results confirm the potential of the artificial magnetic bacteria for future engineering applications. KEY POINTS: • Sporosarcina pasteurii is first time successfully engineered into artificial magnetic bacteria. • The artificial magnetic bacteria show excellent performance of targeted transportation and directional deposition of CaCO3 in microfluidic chip. • The emergence of artificial magnetic bacteria promotes paradigm shift of next generation environmentally friendly biomineralization.

Modified geosynthetic clay liners bentonite for barriers of Cr (VI) in contaminated soil.

Hydroxy-Fe-Al and cetyltrimethylammonium bromide (CTMAB) were chosen to modified Na-bentonite (Na-bent). The characteristics of Na-bent and modified bentonites were determined with scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR) and zeta potential. It was found that CTMAB mainly entered the interlayer and hydroxy-Fe-Al groups were mostly loaded on the external surface of the Na-bent, respectively. The efficiency to remove Cr (VI) of Na-bent, organic modified bentonite (O-bent), inorganic modified bentonite (I-bent) and composite modified bentonite (Co-bent) followed the order: Co-bent > I-bent > O-bent > Na-bent. Adsorption experiments were carried out by the batch contact method. The highest removal rate of Cr (VI) by Co-bent was found to be 96.2% at optimal pH = 4. The Cr (VI) uptake on Co-bent from 50 mg/L solution rapidly attained equilibrium within 10 min, and the pesudo-second-order kinetic model could provide satisfactory fitting of the kinetic data (R2 = 0.999) compared to the intraparticle diffusion model (R2 = 0.585). The adsorption data were applied to the Langmuir, Freundlich, Temkin isotherm model. The Langmuir was found to be the most suitable equation to fit the experimental data (R2 = 0.956) with a high Cr (VI) adsorption capacity of 27.472 mg/g, and RL values (0.012-0.035) also indicated the adsorption could be accepted. The present study confirmed that Co-bent would be one of candidates for Cr (VI) adsorbent.

New Insights into Phase-Mechanism Relationship of Mgx MnO2 Nanowires in Aqueous Zinc-Ion Batteries.

In response to the call for safer energy storage systems, rechargeable aqueous manganese-based zinc-ion (Zn-ion) batteries using mild electrolyte have attracted extensive attention. However, the charge-storage mechanism and structure change of manganese-based cathode remain controversial topics. Herein, a systematic study to understand the electrochemical behavior and charge storage mechanism based on a 3 × 3 tunnel-structured Mgx MnO2 as well as the correspondence between different tunnel structures and reaction mechanisms are reported. The energy storage mechanism of the different tunnel structure is surface faradaic dissolution/deposition coupled with an intercalation mechanism of cations in aqueous electrolyte, which is confirmed by in situ X-ray diffraction, in situ Raman and ex situ extended X-ray absorption fine structure. The deposition process at the cathode is partially reversible due to the accumulation of a birnessite layer on the surface. Compared to smaller tunnels, the 3 × 3 tunnel structure is more conducive to deposit new active materials from the electrolyte. Therefore, pristine Mgx MnO2 nanowires with large tunnels display an excellent cycling performance. This work sheds light on the relationship between the tunnel structure and Mn2+ deposition and provides a promising cathode material design for aqueous Zn-ion batteries.

Near-Infrared-Responsive Photo-Driven Nitrogen Fixation Enabled by Oxygen Vacancies and Sulfur Doping in Black TiO2-xSy Nanoplatelets.

Solar-driven nitrogen fixation is a promising clean and mild approach for ammonia synthesis beyond the conventional energy-intensive Haber-Bosch process. However, it is still challenging to design highly active, stable, and low-cost photocatalysts for activating inert N2 molecules. Herein, we report the synthesis of anatase-phase black TiO2-xSy nanoplatelets enriched with abundant oxygen vacancies and sulfur anion dopants (VO-S-rich TiO2-xSy) by ion exchange method at gentle conditions. The VO-S-rich TiO2-xSy nanoplatelets display a narrowed bandgap of 1.18 eV and much stronger light absorption that extends to the near-infrared (NIR) region. The co-presence of oxygen vacancies and sulfur dopants facilitates the adsorption of N2 molecules, promoting the reaction rate of N2 photofixation. Theoretical calculations reveal the synergistic effect of oxygen vacancies and sulfur dopants on visible-NIR light adsorption and photoexcited carrier transfer/separation. The VO-S-rich TiO2-xSy exhibits improved ammonia yield rates of 114.1 µmol g-1 h-1 under full-spectrum irradiation and 86.2 µmol g-1 h-1 under visible-NIR irradiation, respectively. Notably, even under only NIR irradiation (800-1100 nm), the VO-S-rich TiO2-xSy can still deliver an ammonia yield rate of 14.1 µmol g-1 h-1. This study presents the great potential to regulate the activity of photocatalysts by rationally engineering the defect sites and dopant species for room-temperature N2 reduction.

Controlled growth and ion intercalation mechanism of monocrystalline niobium pentoxide nanotubes for advanced rechargeable aluminum-ion batteries.

Rechargeable aluminum-ion batteries (RAIBs) have attracted increasing attention owing to their high theoretical volumetric capacity, high resource abundance, and good safety performance. However, the existing RAIB systems usually exhibit relatively low specific capacities limited by the cathode materials. In this study, we developed a one-step chemical vapor deposition method to prepare single-crystal orthogonal Nb2O5 nanotubes for serving as high-performance electrode materials for RAIBs, showing a high reversible capability of 556 mA h g-1 at 25 mA g-1 and good thermal endurability at elevated temperatures (50 °C). A combination of a series of detailed ex situ structural characterization studies verified the reversible intercalation/deintercalation of chloroaluminate anions (AlCl4-) into/from the (001) planes of monocrystalline Nb2O5 nanotubes. It also revealed that the nanoarchitecture of Nb2O5 nanotubes with thin tube walls, hollow inner space and a short ion transport distance is conducive to the rapid kinetics of the insertion/extraction process. This work provides a promising route to design high-performance electrode materials based on transition metal compounds for RAIBs via the rational modulation of their structure and morphology.

Intermetallic SnSb nanodots embedded in carbon nanotubes reinforced nanofabric electrodes with high reversibility and rate capability for flexible Li-ion batteries.

Tin (Sn) based anode materials have been regarded as promising alternatives for graphite in lithium ion batteries (LIBs) due to their high theoretical specific capacity and conductivity. However, their practical application is severely restrained by the drastic volume variation during cycling processes. Here we report the preparation of intermetallic SnSb nanodots embedded in carbon nanotube reinforced N-doped carbon nanofibers (SnSb-CNTs@NCNFs) as a free-standing and flexible anode for LIBs. In this unique structure, the SnSb nanodots are well protected by the NCNFs and exhibit greatly reduced volume change. The mechanical strength and conductivity of the nanofabric electrode are further improved by the embedded CNTs. Benefiting from these advantages, the SnSb-CNTs@NCNFs anode delivers a high reversible capacity of 815 mA h g-1 at 100 mA g-1, a high rate capability (370 mA h g-1 at 5000 mA g-1) and a long cycle life (451 mA h g-1 after 1000 cycles at 2000 mA g-1). When assembled into flexible pouch cells, the full cells based on SnSb-CNTs@NCNFs anodes also exhibit high flexibility and good lithium storage performances.

All-polymer particulate slurry batteries.

Redox flow batteries are promising for large-scale energy storage, but some long-standing problems such as safety issues, system cost and cycling stability must be resolved. Here we demonstrate a type of redox flow battery that is based on all-polymer particulate slurry electrolytes. Micro-sized and uniformly dispersed all-polymer particulate suspensions are utilized as redox-active materials in redox flow batteries, breaking through the solubility limit and facilitating the application of insoluble redox-active materials. Expensive ion-exchange membranes are replaced by commercial dialysis membranes, which can simultaneously realize the rapid shuttling of H+ ions and cut off the migration of redox-active particulates across the separator via size exclusion. In result, the all-polymer particulate slurry redox flow batteries exhibit a highly reversible multi-electron redox process, rapid electrochemical kinetics and ultra-stable long-term cycling capability.

Efficient photocatalytic nitrogen fixation under ambient conditions enabled by the heterojunctions of n-type Bi2MoO6 and oxygen-vacancy-rich p-type BiOBr.

N2 fixation is one of the most important chemical reactions in the ecosystem of our planet. However, the industrial Haber-Bosch ammonia synthesis process is restricted by harsh reaction conditions (350-550 °C, 150-350 atm) and undesirable environmental effects (a large amount of CO2 emission). Photocatalytic N2 fixation is promising for achieving sustainable ammonia synthesis under ambient conditions with lower energy input and less environmental issues. However, the known photocatalysts for N2 reduction under mild conditions still face the great challenge of very low energy conversion efficiency. Herein, we report a facile solution-phase method to prepare the heterojunctions based on n-type Bi2MoO6 nanorods and oxygen-vacancy-rich p-type BiOBr nanosheets (Bi2MoO6/OV-BiOBr). Originating from the formation of p-n junctions and suitable bandgap configuration, the Bi2MoO6/OV-BiOBr heterojunctions exhibit effective light utilization and photogenerated electron-hole separation properties. Moreover, it is confirmed that the oxygen vacancies on BiOBr nanosheets are propitious to the adsorption and activation of N2 molecules. Benefiting from these merits, the Bi2MoO6/OV-BiOBr heterojunctions exhibit improved photocatalytic performance for N2 conversion to ammonia without any noble metal co-catalysts and sacrificial reagents under ambient conditions.

Surface plasmon resonance enhanced direct Z-scheme TiO2/ZnTe/Au nanocorncob heterojunctions for efficient photocatalytic overall water splitting.

Solar-driven photocatalytic overall water splitting is regarded as one of the ideal strategies to generate renewable hydrogen energy without the initiation of environmental issues. However, there are still a few remaining challenges to develop wide-light-absorption and stable photocatalysts for the simultaneous production of H2 and O2 in pure water without sacrificial reagents. Herein, we report the design and preparation of Z-scheme TiO2/ZnTe/Au nanocorncob heterojunctions by homogeneously decorating Au nanoparticles onto the surface of core-shell TiO2/ZnTe coaxial nanorods for highly efficient overall water splitting. With the appropriate band structure of TiO2/ZnTe heterojunctions and the surface plasmon resonance enhancement of Au nanoparticles, the well-designed TiO2/ZnTe/Au nanocorncob heterojunctions can synergistically make effective utilization of broad-range solar light illunimation and enhance the separation efficency of electron-hole pairs, as evidenced by UV-Vis absorption and time-resolved photoluminescence spectroscopy. Photoelectrochemical characterization confirms that the water-splitting reaction on TiO2/ZnTe/Au nanocorncobs is mainly carried out via a two-electron/two-electron transfer process with an intermediate product of H2O2. As a result, the TiO2/ZnTe/Au nanocorncob photocatalyst can generate H2 and O2 with a stoichiometric ratio of 2 : 1 under light irradiation without any sacrificial agents, exhibiting a high H2 production rate of 3344.0 µmol g-1 h-1 and a solar-to-hydrogen (STH) efficiency of 0.98%. Moreover, the TiO2/ZnTe/Au nanocorncob heterojunctions show high stability and well-preserved morphological integrity after long-term photocatalytic tests. This study provides a prototype route to produce clean hydrogen energy from only sunlight, pure water, and rationally-designed heterojunction photocatalysts.

The dealloying-lithiation/delithiation-realloying mechanism of a breithauptite (NiSb) nanocrystal embedded nanofabric anode for flexible Li-ion batteries.

Antimony (Sb) based anodes with high conductivity and capability have shown great promise for applications in lithium ion batteries (LIBs). However, they often suffer from poor cycling stability because of the drastic volume variation and structural degradation on undergoing lithiation-delithiation processes. Here we demonstrate a novel Sb-based anode with a free-standing structure realized by uniformly implanting intermetallic compound breithauptite (nickel antimonide, NiSb) nanocrystals into nitrogen-doped carbon nanofibers (NiSb@NCNFs). The discharge/charge behavior of NiSb@NCNFs was systematically investigated by ex situ characterization, which revealed a special "dealloying-lithiation/delithiation-realloying" cycling mechanism. The NiSb nanocrystals possess high lithium storage capacity, and the interconnected network of NCNFs can accommodate the volume variation of encapsulated NiSb nanoparticles, while also providing smooth pathways for charge transport. Compared to other Sb-based anodes, the NiSb@NCNF anode presents exceptional reversible capacity (720 mA h g-1 at a current density of 100 mA g-1) and greatly enhanced cycling life at high rates (510 mA h g-1 after 2000 cycles at 2000 mA g-1). Furthermore, the free-standing NiSb@NCNF anode is free of binders, conductive additives and metal current collectors, exhibiting high flexibility and remarkable performances for the construction of flexible and bendable soft-packed full Li-ion pouch cells.

Nitrogen-Doped Carbon Nanotube Forests Planted on Cobalt Nanoflowers as Polysulfide Mediator for Ultralow Self-Discharge and High Areal-Capacity Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries with high theoretical energy density have caught enormous attention for electrochemical power source applications. However, the development of Li-S batteries is hindered by the electrochemical performance decay that resulted from low electrical conductivity of sulfur and serious shuttling effect of intermediate polysulfides. Moreover, the areal capacity is usually restricted by the low areal sulfur loadings (1.0-3.0 mg cm-2). When the areal sulfur loading increases to a practically accepted level above 3.0-5.0 mg cm-2, the areal capacity and cycling life tend to become inferior. Herein, we report an effective polysulfide mediator composed of nitrogen-doped carbon nanotube (N-CNT) forest planted on cobalt nanoflowers (N-CNTs/Co-NFs). The abundant pores in N-CNTs/Co-NFs can allow a high sulfur content (78 wt %) and block the dissolution/diffusion of polysulfides via physical confinement, and the Co nanoparticles and nitrogen heteroatoms (4.3 at. %) can enhance the polysulfide retention via strong chemisorption capability. Moreover, the planted N-CNT forest on N-CNTs/Co-NFs can enable fast electron transfer and electrolyte penetration. Benefiting from the above merits, the sulfur-filled N-CNTs/Co-NFs (S/N-CNTs/Co-NFs) cathodes with high areal sulfur loadings exhibit low self-discharge rate, high areal capacity, and stable cycling performance.

Atomic Substitution Enabled Synthesis of Vacancy-Rich Two-Dimensional Black TiO2- x Nanoflakes for High-Performance Rechargeable Magnesium Batteries.

Rechargeable magnesium (Mg) batteries assembled with dendrite-free, safe, and earth-abundant metal Mg anodes potentially have the advantages of high theoretical specific capacity and energy density. Nevertheless, owing to the large polarity of divalent Mg2+ ions, the insertion of Mg2+ into electrode materials suffers from sluggish kinetics, which seriously limit the performance of Mg batteries. Herein, we demonstrate an atomic substitution strategy for the controlled preparation of ultrathin black TiO2- x (B-TiO2- x) nanoflakes with rich oxygen vacancies (OVs) and porosity by utilizing ultrathin 2D TiS2 nanoflakes as precursors. We find out that the presence of OVs in B-TiO2- x electrode material can greatly improve the electrochemical performances of rechargeable Mg batteries. Both experimental results and density functional theory simulations confirm that the introduction of OVs can remarkably enhance the electrical conductivity and increase the number of active sites for Mg2+ ion storage. The vacancy-rich B-TiO2- x nanoflakes exhibit high reversible capacity and good capacity retention after long-term cycling at large current densities. It is hoped that this work can provide valuable insights and inspirations on the defect engineering of electrode materials for rechargeable magnesium batteries.

Oxygen Vacancy Engineering Promoted Photocatalytic Ammonia Synthesis on Ultrathin Two-Dimensional Bismuth Oxybromide Nanosheets.

The catalytic conversion of nitrogen to ammonia is one of the most important processes in nature and chemical industry. However, the traditional Haber-Bosch process of ammonia synthesis consumes substantial energy and emits a large amount of carbon dioxide. Solar-driven nitrogen fixation holds great promise for the reduction of energy consumption and environmental pollution. On the basis of both experimental results and density functional theory calculations, here we report that the oxygen vacancy engineering on ultrathin BiOBr nanosheets can greatly enhance the performance for photocatalytic nitrogen fixation. Through the addition of polymetric surfactant (polyvinylpyrrolidone, PVP) in the synthesis process, VO-BiOBr nanosheets with desirable oxygen vacancies and dominant exposed {001} facets were successfully prepared, which effectively promote the adsorption of inert nitrogen molecules at ambient condition and facilitate the separation of photoexcited electrons and holes. The oxygen defects narrow the bandgap of VO-BiOBr photocatalyst and lower the energy requirement of exciton generation. In the case of the specific surface areas are almost equal, the VO-BiOBr nanosheets display a highly improved photocatalytic ammonia production rate (54.70 µmol·g-1·h-1), which is nearly 10 times higher than that of the BiOBr nanoplates without oxygen vacancies (5.75 µmol·g-1·h-1). The oxygen vacancy engineering on semiconductive nanomaterials provides a promising way for rational design of catalysts to boost the rate of ammonia synthesis under mild conditions.

Highly Branched VS4 Nanodendrites with 1D Atomic-Chain Structure as a Promising Cathode Material for Long-Cycling Magnesium Batteries.

Rechargeable magnesium batteries have attracted increasing attention due to the high theoretical volumetric capacities, dendrite formation-free characteristic and low cost of Mg metal anodes. However, the development of magnesium batteries is seriously hindered by the lack of capable cathode materials with long cycling life and fast solid-state diffusion kinetics for highly-polarized divalent Mg2+ ions. Herein, vanadium tetrasulfide (VS4 ) with special one-dimensional atomic-chain structure is reported to be able to serve as a favorable cathode material for high-performance magnesium batteries. Through a surfactant-assisted solution-phase process, sea-urchin-like VS4 nanodendrites are controllably prepared. Benefiting from the chain-like crystalline structure of VS4 , the S22- dimers in the VS4 nanodendrites provide abundant sites for Mg2+ insertion. Moreover, the VS4 atomic-chains bonded by weak van der Waals forces are beneficial to the diffusion kinetics of Mg2+ ions inside the open channels of VS4 . Through a series of systematic ex situ characterizations and density functional theory calculations, the magnesiation/demagnesiation mechanism of VS4 are elucidated. The VS4 nanodendrites present remarkable performance for Mg2+ storage among existing cathode materials, exhibiting a remarkable initial discharge capacity of 251 mAh g-1 at 100 mA g-1 and an impressive long-term cyclability at large current density of 500 mA g-1 (74 mAh g-1 after 800 cycles).

Strong Capillarity, Chemisorption, and Electrocatalytic Capability of Crisscrossed Nanostraws Enabled Flexible, High-Rate, and Long-Cycling Lithium-Sulfur Batteries.

The development of flexible lithium-sulfur (Li-S) batteries with high energy density and long cycling life are very appealing for the emerging flexible, portable, and wearable electronics. However, the progress on flexible Li-S batteries was limited by the poor flexibility and serious performance decay of existing sulfur composite cathodes. Herein, we report a freestanding and highly flexible sulfur host that can simultaneously meet the flexibility, stability, and capacity requirements of flexible Li-S batteries. The host consists of a crisscrossed network of carbon nanotubes reinforced CoS nanostraws (CNTs/CoS-NSs). The CNTs/CoS-NSs with large inner space and high conductivity enable high loading and efficient utilization of sulfur. The strong capillarity effect and chemisorption of CNTs/CoS-NSs to sulfur species were verified, which can efficiently suppress the shuttle effect and promote the redox kinetics of polysulfides. The sulfur-encapsulated CNTs/CoS-NSs (S@CNTs/CoS-NSs) cathode in Li-S batteries exhibits superior performance, including high discharge capacity, rate capability (1045 mAh g-1 at 0.5 C and 573 mAh g-1 at 5.0 C), and cycling stability. Intriguingly, the soft-packed Li-S batteries based on S@CNTs/CoS-NSs cathode show good flexibility and stability upon bending.

Progress and Perspective of Electrocatalytic CO2 Reduction for Renewable Carbonaceous Fuels and Chemicals.

The worldwide unrestrained emission of carbon dioxide (CO2) has caused serious environmental pollution and climate change issues. For the sustainable development of human civilization, it is very desirable to convert CO2 to renewable fuels through clean and economical chemical processes. Recently, electrocatalytic CO2 conversion is regarded as a prospective pathway for the recycling of carbon resource and the generation of sustainable fuels. In this review, recent research advances in electrocatalytic CO2 reduction are summarized from both experimental and theoretical aspects. The referred electrocatalysts are divided into different classes, including metal-organic complexes, metals, metal alloys, inorganic metal compounds and carbon-based metal-free nanomaterials. Moreover, the selective formation processes of different reductive products, such as formic acid/formate (HCOOH/HCOO-), monoxide carbon (CO), formaldehyde (HCHO), methane (CH4), ethylene (C2H4), methanol (CH3OH), ethanol (CH3CH2OH), etc. are introduced in detail, respectively. Owing to the limited energy efficiency, unmanageable selectivity, low stability, and indeterminate mechanisms of electrocatalytic CO2 reduction, there are still many tough challenges need to be addressed. In view of this, the current research trends to overcome these obstacles in CO2 electroreduction field are summarized. We expect that this review will provide new insights into the further technique development and practical applications of CO2 electroreduction.

Porous-Shell Vanadium Nitride Nanobubbles with Ultrahigh Areal Sulfur Loading for High-Capacity and Long-Life Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries hold great promise for the applications of high energy density storage. However, the performances of Li-S batteries are restricted by the low electrical conductivity of sulfur and shuttle effect of intermediate polysulfides. Moreover, the areal loading weights of sulfur in previous studies are usually low (around 1-3 mg cm-2) and thus cannot fulfill the requirement for practical deployment. Herein, we report that porous-shell vanadium nitride nanobubbles (VN-NBs) can serve as an efficient sulfur host in Li-S batteries, exhibiting remarkable electrochemical performances even with ultrahigh areal sulfur loading weights (5.4-6.8 mg cm-2). The large inner space of VN-NBs can afford a high sulfur content and accommodate the volume expansion, and the high electrical conductivity of VN-NBs ensures the effective utilization and fast redox kinetics of polysulfides. Moreover, VN-NBs present strong chemical affinity/adsorption with polysulfides and thus can efficiently suppress the shuttle effect via both capillary confinement and chemical binding, and promote the fast conversion of polysulfides. Benefiting from the above merits, the Li-S batteries based on sulfur-filled VN-NBs cathodes with 5.4 mg cm-2 sulfur exhibit impressively high areal/specific capacity (5.81 mAh cm-2), superior rate capability (632 mAh g-1 at 5.0 C), and long cycling stability.

Self-Templated Formation of Interlaced Carbon Nanotubes Threaded Hollow Co3S4 Nanoboxes for High-Rate and Heat-Resistant Lithium-Sulfur Batteries.

Lithium-sulfur batteries (Li-S) have attracted soaring attention due to the particularly high energy density for advanced energy storage system. However, the practical application of Li-S batteries still faces multiple challenges, including the shuttle effect of intermediate polysulfides, the low conductivity of sulfur and the large volume variation of sulfur cathode. To overcome these issues, here we reported a self-templated approach to prepare interconnected carbon nanotubes inserted/wired hollow Co3S4 nanoboxes (CNTs/Co3S4-NBs) as an efficient sulfur host material. Originating from the combination of three-dimensional CNT conductive network and polar Co3S4-NBs, the obtained hybrid nanocomposite of CNTs/Co3S4-NBs can offer ultrahigh charge transfer properties, and efficiently restrain polysulfides in hollow Co3S4-NBs via the synergistic effect of structural confinement and chemical bonding. Benefiting from the above advantages, the S@CNTs/Co3S4-NBs cathode shows a significantly improved electrochemical performance in terms of high reversible capacity, good rate performance, and long-term cyclability. More remarkably, even at an elevated temperature (50 °C), it still exhibits high capacity retention and good rate capacity.