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Sodium-ion batteries (SIBs) have recently attracted great interest and been considered an ideal alternative toward lithiumion batteries due to the low cost and abundance of sodium resources on the earth. [1][2][3] However, the intrinsic larger radius (1.06 Å) of Na + than that of Li + (0.76 Å), leads to a sluggish kinetics and grievous volume expansion during Na + insertion and extraction as well as low reversible capacity and fast capacity fading for SIBs. [4,5] The key to widespread application for SIBs is to seek a suitable electrode material which is expected to simultaneously possess high theoretical capacity, low volume expansion, and excellent electric conductivity. [6] To date, considerable efforts have been devoted to developing suitable anode materials for SIBs, such as transition metal dichalcogenides (M = Mo and W), [7,8] alloying compounds (Sb, Sn, and SnO 2 ), [9][10][11] titanates, [12] and 2D metal carbides. [13] It is found that most Sodium-ion batteries (SIBs) are considered a prospective candidate for large-scale energy storage due to the merits of abundant sodium resources and low cost. However, a lack of suitable advanced anode materials has hindered further applications. Herein, metal-semiconductor mixed phase twinned hierarchical (MPTH) MoS 2 nanowires with an expanded interlayer (9.63 Å) are engineered and prepared using MoO 3 nanobelts as a selfsacrificed template in the presence of a trace amount of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O as initiator. The greatly expanded interlayer spacing accelerates Na + insertion/extraction kinetics, and the metal-semiconductor mixed phase enhances electron transfer ability and stabilizes electrode structure during cycling. Benefiting from the structural merits, the MPTH MoS 2 electrode delivers high reversible capacities of 200 mAh g −1 at 0.1 A g −1 for 200 cycles and 154 mAh g −1 at 1 A g −1 for 2450 cycles in the voltage range of 0.4-3.0 V. Strikingly, the electrode maintains 6500 cycles at a current density of 2 A g −1 , corresponding to a capacity retention of 82.8% of the 2nd cycle, overwhelming the all reported MoS 2 cycling results. This study provides an alternative strategy to boost SIB cycling performance in terms of reversible capacity by virtue of interlayer expansion and structure stability.

Electrochemical semihydrogenation (ECSH) of alkynes to alkenes is an ideal alternative to traditional thermal semihydrogenation, and yet is limited by low conversion yield and product selectivity. Here, we offer an insight into the catalyst design from the viewpoint of an interfacial water structure toward highly active and selective ECSH. In situ Raman spectroscopy measurements combined with theoretical calculations reveal that the structure of interfacial water on Pd nanosheets can be altered by Fe doping toward trihedrally coordinated water and dangling O–H water, which in turn boosts the activity and selectivity in ECSH. Remarkably, the PdFe nanosheets can sustain continuous 264 h of electrolysis with 100-fold amplified amount of alkynes production in a flow cell. We also demonstrate the incomparable superiority for ECSH of alkynes to alkenes in terms of performance, energy, and cost.

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The atomically monodispersed dual‐atom nanozyme not only possesses the advantages of homogeneous active centers and high atomic utilization efficiency but also exhibits amazing synergistic effect for higher catalytic activities than single‐atom nanozyme. However, how to construct dual‐atom nanozyme with multi‐enzyme cascade capacity for protecting against brain tissue damage is a great challenge. Herein, for coping with the secondary damage to brain tissue caused by the explosive generation of reactive oxygen species(ROS) during cerebral ischemia‐reperfusion, a multi‐enzyme cascade antioxidant system is constructed by encapsulating dual‐Fe‐atom nanozyme (Fe2NC) in a selenium‐containing MOF (Se‐MOF) shell layer. The designed dual‐Fe‐atom nanozyme exhibits higher superoxide dismutase‐like, catalase‐like, and even oxidase‐like activities than single‐atom Fe (Fe1NC) nanozyme, and moreover, the Se‐MOF shell layer not only acts as a glutathione peroxidase mimic, but also improves the stability and biocompatibility of the Fe2NC nanozyme obviously. The synergistic effect of Fe2NC has been demonstrated to be the main reason for the higher activity by density functional theory calculations. In vitro and in vivo results reveal that the multifunctional antioxidant Fe2NC@Se nanoparticles can counteract oxidative damage and inhibit neural apoptosis after cerebral ischemia‐reperfusion injury by effectively eliminating intracellular ROS and potentially inhibiting the ASK1/JNK apoptotic signaling pathway.

No abstract

The industrial Haber‐Bosch process for ammonia synthesis is extremely important in modern society. However, it is energy intensive and leads to severe pollution, which has motivated eco‐friendly NH3 synthesis research. Electroreduction of contaminant nitrate ions back to NH3 is an effective complement but is still limited by low NH3 yields and nitrate‐to‐NH3 selectivities. In this study, the electrochemical nitrate reduction reaction (NTRR) is carried out over a single‐atom Cu catalyst. Atomically dispersed Cu sites anchored on dual‐mesoporous N‐doped carbon framework display excellent NTRR performance with NH3 production rate of 13.8 molNH3  gcat−1 h−1 and NO3−‐to‐NH3 faradaic efficiency (FE) of 95.5 % at −1.0 V. Cu−N−C catalyst can sustain continuous 120 h NTRR test in the simulated NH3 synthesis scenarios with large current density (about 200 mA cm−2) and amplified volume of NO3− solution (9 times). Theoretical calculations reveal that atomically dispersed Cu1−N4 sites reduce the energy barrier of potential‐determining step in NTRR and promote the decomposition of primary intermediate in NO3−‐to‐N2 process. These findings provide a guideline for the rational design of highly active, selective and durable electrocatalysts for the NTRR.

Both doping and compositing in TiO 2 are exceedingly effective strategies to overcome the compound's shortcomings, such as invalid visible-light response and enormous recombination of photogenerated carriers. Herein, a convenient and costeffective route has been put forward to in situ synthesize nanolayered heterostructure based on N-doped TiO 2 nanoparticles and Ndoped carbon (N-TiO 2 /NC) using 2D layered N-MXene (N−Ti 3 C 2 T x ) as the template. The as-obtained N-TiO 2 /NC nanocomposite displays greatly enhanced visible light absorption property, superior carrier separation and transport ability. As a result, the nanolayered N-TiO 2 /NC heterostructure exhibits a satisfactory H 2 evolution rate from water-splitting (102.6 μmol g −1 h −1 ) under visible-light without any additional cocatalyst. The study provides a new strategy for the synthesis of defective nanoheterostructure and expands the applications of MXene family.