energy density and good cycle stability is believed as a promising strategy to solve this issue. For example, Li-CO 2 batteries which have been developed on the basis of Li-O 2 batteries have recently attracted attention. This battery system not only offers a high energy density for electrochemical energy storage but also alleviates the greenhouse effect by capturing CO 2 . [5] More recently, Li-CO 2 batteries have been attempted as new energy carriers to store renewable energy, in which Li 2 CO 3 is the main discharge product: 4Li + 3CO 2 + 4e − ↔ 2Li 2 CO 3 + C (E 0 = 2.80 V vs Li/Li). [6][7][8] Unfortunately, this incipient prototype battery can only run about ten cycles. The main bottlenecks are related to two aspects. First, the insert decomposition of Li 2 CO 3 discharge product is prone to adhere on the cathode surface, and then remarkably reduces the capacity. [8] Second, the aggregation of Li 2 CO 3 product will block the channels of gas diffusion and reduce the conductivity of electrode, resulting in a very high charge potential (>4.3 V). [6] In this regard, a cathode with a high surface area which could promote the reversibility of the Li 2 CO 3 discharge product is desirable to accelerate the practical applications of Li-CO 2 batteries. [9] Akin to the development of Li-O 2 batteries, there are two approaches to improve the electrochemical properties of the cathodes. On the one hand, the direct optimization of cathode structures has been regarded as a simple method to improve the properties of Li-CO 2 batteries. For instance, Zhou et al. [10,11] successfully examine graphene and carbon nanotubes (CNTs) as the cathodes, in which Li-CO 2 batteries operate for 20 cycles with an overpotential of 1.78 V at 50 mA g −1 under a limitative capacity of 1000 mA h g −1 . Dai et al. [12] design two graphenebased materials with defective structures for Li-CO 2 batteriesholey graphene and B,N-co-doped holey graphene, which show a cycling lifetime of over 200 cycles at 1 A g −1 , but suffer from a large overpotential (about 1.8 V at 1 A g −1 ). Liu et al. [13] first introduce CNTs which decorated with RuO 2 as cathode materials for Li-CO 2 batteries, which can deliver a high specific capacity together with a lower overpotential.On the other hand, the development of new catalysts is another effective method to enhance the electrochemical properties of Li-CO 2 batteries. For example, the cobalt-titanium-layered oxide-RuO 2 composite with a low over-potential of 0.6 V has Li-CO 2 batteries can not only capture CO 2 to solve the greenhouse effect but also serve as next-generation energy storage devices on the merits of economical, environmentally-friendly, and sustainable aspects. However, these batteries are suffering from two main drawbacks: high overpotential and poor cyclability, severely postponing the acceleration of their applications. Herein, a new Co-doped alpha-MnO 2 nanowire catalyst is prepared for rechargeable Li-CO 2 batteries, which exhibits a high capacity (8160 mA h g −1 at a current density of 100 mA g ...

The research studies on the functionalization of two-dimensional (2D) materials (such as black phosphorus) are essential for the development of self-assembled nanomaterials. In this work, the composite films based on black phosphorus (BP) and dyes were prepared by Langmuir–Blodgett (LB) technology. In order to make better use of the characteristics of BP, it was exfoliated to form BP nanosheets (BPNS) and then modified with polyethyleneimine (PEI) to maintain stability. UV–vis, Raman, atomic force microscopy, and other characterizations prove that the composite films are successfully synthesized, which may be attributed to electrostatic forces and π–π stacking forces. Interestingly, the obtained BPNS-PEI-TPPS composite LB film shows good sensitivity to acid and alkali gas. In addition, the results of surface-enhanced Raman scattering (SERS) indicated that the BPNS-PEI-TsNiPc composite film had surface-enhanced performance for crystal violet molecules. The current work provides new clues for the preparation and development of BP-based self-assembled film materials for gas sensors and SERS.

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Light-weight magnesium alloys with high strength are especially desirable for the applications in transportation, aerospace, electronic components, and implants owing to their high stiffness, abundant raw materials, and environmental friendliness. Unfortunately, conventional strengthening methods mainly involve the formation of internal defects, in which particles and grain boundaries prohibit dislocation motion as well as compromise ductility invariably. Herein, we report a novel strategy for simultaneously achieving high specific yield strength (∼160 kN m kg) and good elongation (∼23.6%) in a duplex magnesium alloy containing 8 wt % lithium at room temperature, based on the introduction of densely hierarchical {101̅1}-{101̅1} double contraction nanotwins (DCTWs) and full-coherent hexagonal close-packed (hcp) particles in twin boundaries by ultrahigh pressure technique. These hierarchical nanoscaled DCTWs with stable interface characteristics not only bestow a large fraction of twin interface but also form interlaced continuous grids, hindering possible dislocation motions. Meanwhile, orderly aggregated particles offer supplemental pinning effect for overcoming latent softening roles of twin interface movement and detwinning process. The processes lead to a concomitant but unusual situation where double contraction twinning strengthens rather than weakens magnesium alloys. Those cutting-edge results provide underlying insights toward designing alternative and more innovative hcp-type structural materials with superior mechanical properties.

Photocatalysts play an increasingly important role in environmental remediation polluted by industrial wastewater. However, the preparation of adsorbents and catalysts with high activity by simple and easy methods is still a great challenge. Here, sandwich-like composite catalyst Cu2O/TiO2/Ti3C2 was prepared by an easily available solvent reduction measure for the highly efficient catalytic nitro compounds. In particular, sandwich-like composite catalyst Cu2O/TiO2/Ti3C2 exhibits excellent catalysis for 2-nitroaniline (2-NA) and 4-nitrophenol (4-NP), and its pseudo-first-order reaction rate constants (k) are 0.163 and 0.114 min–1, respectively. Interestingly, even after eight consecutive cycles of catalytic experiments, the conversion rates of catalytic 2-NA and 4-NP are still greater than 95 and 92%, respectively, demonstrating that the obtained catalyst has excellent catalytic capability and a high reutilization rate. The excellent catalytic performances of Cu2O/TiO2/Ti3C2 can be attributed to the fact that Ti3C2 provides a greater reaction site for the formation of Cu2O and reduces the aggregation during the formation of Cu2O by in situ synthesis. Therefore, ternary composite catalyst Cu2O/TiO2/Ti3C2 prepared by solvent reduction not only supplies a technical method for the catalytic reaction of MXene-based material but also lays the foundation for the development of new photocatalysts.