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Reinforced Lewis covalent bond induced by twinborn nitride heterostructure as the sulfur host enhances the Lewis covalent bond with S, catalyzes redox reactions, and improves the e−and Li+transmission.

• MXene derivative Ta 4 C 3 -Ta 2 O 5 heterostructure was firstly reported as bi-functional barrier for Li-S batteries. • A one stone two birds strategy is designed to inhibit polysulfides shuttle and protect Li metal anode. • Ta 4 C 3 -Ta 2 O 5 acquired strong coulombic interaction with Ta-S and Li-O bondings. • Ta 4 C 3 -Ta 2 O 5 heterostructure works as a robust shielding layer to achieve effective protection for Li metal anode. The shuttle effect of polysulfides during the charging and discharging of lithium-sulfur (Li-S) batteries and the growth of Li dendrites are crucial obstacles to hinder the commercialization of Li-S batteries. Heterostructure engineering is an effective strategy to accelerate catalytic conversion and suppress the dissolution of polysulfides. Herein, we report a Ta 4 C 3 -Ta 2 O 5 heterostructure composite as a bi-functional modified separator that not only achieves effective protection for lithium metal but also accelerates the polysulfides redox kinetics process. This heterostructure possesses efficient chemical anchoring and abundant active sites to immobilize polysulfides by synergistic effect, which endows a stable long cycling performance for Li-S batteries. This corresponds to an initial high capacity of 801.9 mAh g–1 at 1 C with a decay rate of 0.086% for 500 cycles. Due to its high Young's modulus (up to 384 GPa), Ta 4 C 3 contributes to forming a protective layer on the Li metal surface to inhibit the growth of Li dendrites. Accordingly, the symmetrical cell has a stable overpotential for 700 cycles at 20 mA cm–2/20 mAh cm–2. So, this "one stone two birds" design affords a novel perspective for high-energy Li-S battery storage system design and Li metal protection. [Display omitted] [ABSTRACT FROM AUTHOR]

• ST/KBST/ST multilayer film with various ST and KBST layers has been designed originally. • Each KBST layer coated by two ST layers is to better match adjacent structures. • The loose structure of the KBST layer makes it fully compound with the ST layer. • Preheating each layer at 600 °C improves the sandwich-type films in structure and growth. • ST/KBST/ST film shows excellent comprehensive dielectric properties. It is a challenge to reduce the dielectric loss and increase the tunability of pure barium strontium titanate (BST) films for microwave tunable application because these two properties change simultaneously. Herein, a novel composite of strontium titanate (ST) and potassium-doped BST (KBST) has been designed as ST/KBST/ST sandwich-type film with various ST and KBST layers. X-ray diffraction patterns show that the film exhibits cubic perovskite polycrystalline structure composed of BST and ST phase, mainly grow along (110) crystal plane with average grain size of less than 20 nm and decreasing BST phase/ST phase ratio with increasing film thickness. Scanning electron microscope shows that no interfacial layer can be observed, indicating that ST and KBST are fully compounded. Low dielectric loss and high tunability at -10 – 10 V and stable and excellent dielectric properties at 1 GHz are achieved, meeting the needs of microwave tunable application at high frequency. The surface structures are also studied by other analysis methods, and ST/MgBST/ST sandwich-type film is compared. [ABSTRACT FROM AUTHOR]

Lithium metal is expected to be an ideal anode material for future high-energy density lithium batteries. However, the uncontrollable growth of lithium dendrites resulting in a short circuit inside the battery and battery failure has become an obstacle to commercializing lithium metal batteries. In this work, a surface with lithiophilic CoIn3nucleation sites is developed to achieve a uniform lithium deposition by low temperature thermal treatment of super lithiophilic indium foil with three-dimensional (3D) cobalt foam (CoIn3@CF). The CoIn3@CF with 3D porous structure provide channels for rapid Li-ions (Li+) transport and inhibit the volume expansion, while the synergistic effect of lithiophilic CoIn3alloys caused by the multi-facet orientation relationship promote the formation of homogeneous Li+diffusion. As a result, the CoIn3@CF host exhibits long cycling over 2400 h at 40 mA cm−2/1 mA cm−2in symmetric cells. Moreover, a full cell with the Li/CoIn3@CF as anode and LiFePO4as cathode delivers a columbic efficiency more than 99.3% over 800 cycles. This work provides a new perspective for the design of high energy Li anodes.

Photocatalysis is a new type of renewable energy technology used in environmental treatment and hydrogen energy production. In this regard, a new class of photocatalysts, TiO2aerogels, are attractive for having the chemical characteristics of TiO2nanomaterials such as high catalytic activity, good stability, non-toxic, and non-polluting, and the structural characteristics of aerogels such as large specific surface area, high porosity, the 3-dimensional interconnected network structure composed of relatively uniform nanoparticles, and high light transmittance. Here we review the recent progress in TiO2aerogels for photocatalysis, focusing on preparation techniques, the crystalline phases’ influence on photocatalytic properties, the modification of photocatalytic properties, and the analysis and discussion of future development. In particular, we first summarize various preparation techniques, including sol–gel method, nanoparticles self-assembly synthesis, and high-temperature aerosol technique, then detail the structure and composition of TiO2crystalline phases that affect the photocatalytic properties. Subsequently, we discuss strategies to further enhance the photocatalytic properties of TiO2aerogels by the composite of SiO2aerogel semiconductors, the doping of metal dopants, and the doping or composite of non-metallic substances, and elaborate the modification mechanism and the modification effect achieved. Finally, combined with the research status of TiO2aerogels and the development experience of other aerogels, we conduct a reasonable analysis and discussion on their further research directions and industrialization roads.

Solar steam generation can be a practical and sustainable technology for wastewater purification and seawater desalination. However, both the inefficient utilization of solar energy and high complicity/cost of current solar steam generators hinder the scalable application of this technique. Herein, we demonstrate a facile, scalable and low-cost approach to produce highly-efficient solar steam generator via a one-step calcination of commercial melamine sponges (MS) in air. The in-air calcinated MS (AMS) with thermal insulator achieves an ultrafast solar evaporation rate (1.98 kg m−2h−1) and a high photothermal efficiency (~92%) under one sun illumination (1 kW m−2), superior to most reported values. This high solar evaporation rate is attributed to the effective heat localization and adequate water supply in AMS, caused by the low bulk thermal conductivity, high porosity and hydrophilicity of AMS, as well as the set-up of a thermal insulator. The AMS is found to be highly efficient and stable, and it can be used to purify various types of waste water, including river water, seawater, and strong acid/alkaline water. Performance analysis of a large-scale prototype device based on the AMS design for field tests promises significant opportunities for highly-efficient, reusable, portable and low-cost water purification systems.

Numerous efforts have been made to design the cathode of Li–S batteries to enhance reversible capacity and long-term cycling stability. However, challenges remain in achieving high electronic/ionic conductivity and suppressing the shuttle effect, especially for cathodes with high sulfur loading. Here we report a 3D free-standing hierarchical structure of VO2(P) (paramontroseite VO2) nanoparticles grown on nitrogen-doped carbon nanotube (NCNT) arrays as a catalytic host for high-performance sulfur cathodes. In this architecture, the VO2(P) nanoparticles function as catalysts to oxidize the LiPS to produce thiosulfate due to the strong chemical interaction. Furthermore, thiosulfates act as a mediator to catenate long-chain LiPS together and convert short-chain Li2S2/Li2S and surface-bound polythionate complexes. Accordingly, the VO2(P)-NCNT/S cathode exhibits excellent performance with high discharge capacity output (≈1200 mA h g−1at 0.2 C), stable long-term cycling (≈67% retention at 2 C for 500 cycles), and high sulfur loading cycling (initial areal capacity of 10.2 mA h cm−2at 0.2 C for 200 cycles). This nanostructure catalytic cathode with high sulfur loadings, as well as stable cycling performances, is attractive for developing practically useable Li-S batteries.

Graphene has been combined with molybdenum disulfide (MoS2) to ameliorate the poor cycling stability and rate performance of MoS2in lithium ion batteries, yet the underlying mechanisms remain less explored. Here, we develop multiscale modeling to investigate the enhanced electrochemical and thermal transport properties of graphene/MoS2heterostructures (GM-Hs) with a complex morphology. The calculated electronic structures demonstrate the greatly improved electrical conductivity of GM-Hs compared to MoS2. Increasing the graphene layers in GM-Hs not only improves the electrical conductivity but also stabilizes the intercalated Li atoms in GM-Hs. It is also found that GM-Hs with three graphene layers could achieve and maintain a high thermal conductivity of 85.5 W/(m·K) at a large temperature range (100–500 K), nearly 6 times that of pure MoS2[∼15 W/(m·K)], which may accelerate the heat conduction from electrodes to the ambient. Our quantitative findings may shed light on the enhanced battery performances of various graphene/transition-metal chalcogenide composites in energy storage devices.

Transparent conductive oxide (TCO) film acts as the window layer and carrier transport layer of silicon heterojunction (SHJ) solar cells. The optoelectrical and contact properties of TCO films, as well as the sputtering damage, limit the further efficiency improvement. Herein, the microstructure, morphology, and optoelectrical properties of sputtering‐prepared zinc‐doped indium oxide (IZO) are analyzed. The substrate temperature has a significant impact on the film growth and the cell performance. The IZO film is amorphous when substrate temperature is below 200 °C, while it seems the emergence of nanocrystals with the increased temperature, resulting in the highest conductivity (3070 S cm−1) and carrier mobility (47.9 cm2V−1s−1). In addition, the low carrier concentration and surface potential of IZO promote less optical parasitic absorption and higher work function. The IZO films are applied as the contact layer of SHJ solar cells. An impressive efficiency of 24.02% on an M2‐sized wafer is achieved, indicating great potential for the mass production application after careful optimization. Herein, the microstructure, morphology, and optoelectrical properties of sputtering prepared zinc‐doped indium oxide (IZO) are systematically investigated. The IZO film exhibits high conductivity (3070 S cm−1) and carrier mobility (47.9 cm2V−1s−1). An impressive efficiency of 24.02% on an M2‐sized wafer is achieved, indicating great potential for the mass production application after careful optimization.

It is a huge difficulty to improve the comprehensive dielectric performance of barium strontium titanate (BST) films for applications in energy storage, microwave, etc. Herein, on Pt/Ti/SiO2/Si substrate strontium titanate (ST), manganese (Mn) doped BST and yttrium (Y) doped BST layers were attempted to be designed as ST/MnBST/YBST/ … /MnBST/YBST/ST films and prepared by a modified sol–gel method, and structures and performances of the films were studied. X-ray diffraction shows that the films are ABO3perovskite polycrystalline with Ti4+at B sites replaced by some Mn2+and exhibit dense nodular microstructures observed by a scanning electron microscope. The films exhibit optimized comprehensive performance with leakage current density of less than 1E-10 A/cm2at 20 V and dielectric losses of 0.3%–0.4% at 100 kHz and about 1.8% at 1 GHz, meeting the needs of some applications.

Supercapacitors, due to their unique high-power characteristics, are bound to occupy a place in the field of energy storage. Carbon-based supercapacitor is one of the most promising in all material systems. In this work, N-doped/graphene composite activated carbon (AC) is prepared through a facile method as electrodes for the comparison between an aqueous system and an organic system. The obtained AC shows high surface areas of 1600 m2 g[?]1 with a high N content of 11.7 wt% and is simultaneously applied to lithium-ions capacitor (LIC), sodium-ions capacitor (NIC) and potassium ion capacitor (KIC). Electrochemical evaluations indicated that the high N-doped activated carbon-based LIC, NIC and KIC possess different performance and energy storage mechanisms. The KIC exhibits the highest energy density of 50 Wh kg[?]1 at 0.4 A g[?]1 and the most stable cycle performance of three capacitors. This work reveals differences among the three types of ion capacitors, providing clues for the development of high power-energy and long life ion supercapacitors. Moreover, KIC has better performance than LIC, and the reserve of K is much higher than Li, which makes KIC a better application prospect.

Supercapacitors, due to their unique high-power characteristics, are bound to occupy a place in the field of energy storage. Carbon-based supercapacitor is one of the most promising in all material systems. In this work, N-doped/graphene composite activated carbon (AC) is prepared through a facile method as electrodes for the comparison between an aqueous system and an organic system. The obtained AC shows high surface areas of 1600 m2g−1with a high N content of 11.7 wt% and is simultaneously applied to lithium-ions capacitor (LIC), sodium-ions capacitor (NIC) and potassium ion capacitor (KIC). Electrochemical evaluations indicated that the high N-doped activated carbon-based LIC, NIC and KIC possess different performance and energy storage mechanisms. The KIC exhibits the highest energy density of 50 Wh kg−1at 0.4 A g−1and the most stable cycle performance of three capacitors. This work reveals differences among the three types of ion capacitors, providing clues for the development of high power-energy and long life ion supercapacitors. Moreover, KIC has better performance than LIC, and the reserve of K is much higher than Li, which makes KIC a better application prospect.