摘要：Over the past decade,multistable mechanical metamaterials have been widely investigated because of their novel shape reconfigurability and programmable energy *** ability to reversibly reshape among diverse stable states with different energy levels represents the most important feature of the multistable mechanical *** summarize main design strategies of multistable mechanical metamaterials,including those based on self-assembly scheme,snap-through instability,structured mechanism and geometrical frustration,with a focus on the number and controllability of accessible stable *** we concentrate on unusual mechanical properties of these multistable mechanical metamaterials,and present their applications in a wide range of areas,including tunable electromagnetic devices,actuators,robotics,and mechanical logic ***,we discuss remaining challenges and open opportunities of designs and applications of multistable mechanical metamaterials.

摘要：Photocatalytic hydrogen production is considered a promising approach to generating clean sustainable ***,the conventional co-catalyst(e.g.,Pt)used in photocatalytic hydrogen production is high-cost and difficult to ***,we designed and prepared a ternary nanocomposite MXene@Au@Cd S,which can be used in the field of efficient and excellent photocatalytic hydrogen *** MXene@Au@Cd S has a hydrogen production rate of 17,070.43μmol g^-1h^-1(tested for 2 h),which is 1.85 times that of pure Cd S *** improved hydrogen production performance of the MXene@Au@Cd S is attributed to:(i)MXene provides more active adsorption sites and reaction centers for Au and Cd S nanoparticles;(ii)the synergistic effect of Au’s strong surface plasmon resonance expands the optical response range of Cd ***,this work solves the problem of the solid connection between the surface functional groups of photocatalyst,and achieves rapid interface charge transfer and long-term stability during the hydrogen production.

摘要：The thermal conduction of suspended few-layer hexagonal boron nitride （h-BN） sheets was experimentally investigated using a noncontact micro-Raman spectroscopy method. The first-order temperature coefficients for monolayer （1L）, bilayer （2L） and nine-layer （9L） h-BN sheets were measured to be -（3.41 ± 0.12）× 10-2, -（3.15 ± 0.14） × 10-2 and -（3.78 ±0.16）× 10-2 cm-1.K-1, respectively. The room-temperature thermal conductivity of few-layer h-BN sheets was found to be in the range from 227 to 280 W.m-1-K-1, which is comparable to that of bulk h-BN, indicating their potential use as important components to solve heat dissipation problems in thermal management configurations.

摘要：The poor oxygen evolution reaction(OER)activity of two-dimensional(2 D)transition metal carbides(MXenes)is a major obstacle to their application in highperformance water splitting and fuel cells due to the high energy barriers for the absorption of ***,we demonstrate that the lattice oxygen of M_(n)X_(n-1)O_(2)MXenes can be activated by 0 D graphene quantum dots(GQDs),thereby activating the OER via the lattice-oxygen oxidation mechanism(LOM)instead of the conventional adsorbate evolving *** pH-dependent OER activity of M_(n)X_(n-1)O_(2)@GQDs and ^(18)O isotope-labelling experiments with time-of-flight secondary-ion mass spectrometry(TOF-SIMS)provide the direct evidence of ***,the activated lattice oxygen amount can be controlled by the *** as-prepared 0 D/2 D Ti_(3)C_(2)O_(2)@GQDs heterostructure delivers a highly reduced overpotential of 390 mV(bare Ti_(3)C_(2)O_(2):530 mV)at a benchmark current density of 10 mA cm^(-2).Through optimizing the thickness and the additional conductive substrate,the overpotential at 10 mA cm^(-2)decreases to 250 mV,while the Tafel slope is reduced to 39 mV dec^(-1);these values indicate the as-prepared heterostructure is superior to the state-of-the-art MXene-based OER *** work provides a new strategy to enhance the OER activity of M_(n)X_(n-1)O_(2)and extends the application of LOM from perovskite to MXenes.

摘要：The design and synthesis of high‐performance and low‐cost electrocatalysts for the hydrogen evolution reaction(HER),a key half‐reaction in water electrolysis,are *** to their modest hydrogen adsorption energy,ruthenium(Ru)‐based nanomaterials are considered outstanding candidates to replace the expensive platinum(Pt)‐based HER *** this study,we developed an adsorption‐pyrolysis method to construct nitrogen(N)‐doped graphene aerogel(N‐GA)‐supported ultrafine Ru nanocrystal(Ru‐NC)nanocomposites(Ru‐NCs/N‐GA).The particle size of the Ru‐NCs and the conductivity of the N‐GA substrate can be controlled by varying the pyrolysis *** experiments reveal revealed that 10 wt%Ru‐NCs/N‐GA nanocomposites require overpotentials of only 52 and 36 mV to achieve a current density of 10 mA cm^(−2) in 1 mol/L HClO4 and 1 mol/L KOH electrolytes for HER,respectively,which is comparable to 20 wt%Pt/C *** from the ultrafine size and uniform dispersion of the Ru‐NCs,the synergy between Ru and the highly conductive substrate,and the anchoring effect of the N atom,the Ru‐NCs/N‐GA nanocomposites exhibit excellent activity and durability in the pH‐universal HER,thereby opening a new avenue for the production of commercial HER electrocatalysts.

摘要：Sodium-ion batteries are promising for large-scale energy storage due to sodium's low cost and infinite abundance. The most popular cathodes for sodium-ion batteries, i.e., the layered sodium-containing oxides, usually exhibit reversible host rearrangement between P-type and O-type stacking upon charge/discharge. Herein we demonstrate that such host rearrangement is unfavorable and can be suppressed by introducing transition-metal ions into sodium layers. The electrode with stabilized P3-type stacking delivers superior rate capability, high energy efficiency, and excellent cycling performance. Owing to the cation-mixing nature, it performs the lowest lattice strain among all reported cathodes for sodium-ion batteries. Our findings highlight the significance of a stable host for sodium-ion storage and moreover underline the fundamental distinction in material design strategy between lithium-and sodium-ion batteries.

摘要：Rational design and controllable synthesis of efficient electrocatalysts for water oxidation is of significant importance for the development of promising energy conversion systems, in particular integrated photoelectrochemical water splitting devices. Cobalt oxide(Co3O4) nanostructures with mixed valences(Ⅱ,Ⅲ)have been regarded as promising electrocatalysts for the oxygen evolution reaction(OER). They are able to promote catalytic support of OER but with only modest activity. Here, we demonstrate that the OER performance of cubic Co3O4 electrocatalyst is obviously improved when they are anchored on delaminated two-dimensional(2D) Ti3C2 MXene nanosheets. Upon activation the overpotential of the hybrid catalyst delivers 300 m V at a current density of 10 m A cm(2) in basic solutions, which is remarkably lower than those of Ti3C2 MXene and Co3O4 nanocubes. The strong interfacial electrostatic interactions between two components contribute to the exceptional catalytic performance and stability. The enhanced OER activity and facile synthesis make these Co3O4 nanocubes-decorated ultrathin 2D Ti3C2 MXene nanosheets useful for constructing efficient and stable electrodes for high-performance electrochemical water splitting.

摘要：Learning from nature photosynthesis,the development of efficient artificial catalysts for water oxidation is an ongoing ***,a lamellar cobalt oxide(CoO),black phosphorus(BP)and reduced graphene oxide(RGO)hybrid electrocatalyst is *** domains are anchored on RGO and coated with CoO via P–O *** widespread P–O bond network constitutes the proton acceptor and forms a proton exit channel,akin to the use of Asp61 in Photosystem II(PSII).The innermost kernel layer RGO serves as the current collector and forms an electron exit channel,mimicking the function of Tyr161 for charge *** outermost encapsulation CoO layer acts as water oxidation catalyst(WOC).These biology‐inspired features endow an outstanding OER performance of the hybrid material with a low overpotential of 206 mV at a current density of 10 mA cm^(-2).This work provides a new design guide for OER electrocatalysts through constructing two specialized channels for proton and electron transfer.

摘要：Lithium-sulfur(Li-S) batteries have attracted considerable attention due to their high energy density(2600 Wh kg-1). However, its commercialization is hindered seriously by the low loading and utilization rate of sulfur cathodes. Herein, we designed the cellulose-based graphene carbon composite aerogel(CCA) self-standing electrode to enhance the performance of Li-S batteries. The CCA contributes to the mass loading and utilization efficiency of sulfur, because of its unique physical structure: low density(0.018 g cm-3), large specific surface area(657.85 m2 g-1), high porosity(96%), and remarkable electrolyte adsorption(42.25 times). Compared to Al(about 49%), the CCA displayed excellent sulfur use efficiency(86%) and could reach to high area capacity of 8.60 mAh cm-2 with 9.11 mgS loading. Meanwhile,the CCA exhibits the excellent potential for pulse sensing applications due to its flexibility and superior sensitivity to electrical response signals.

摘要：In contrast to heterogeneous network frameworks(e.g.,covalent organic frameworks and metal‐organic frameworks)and porous organic polymers,porous organic cages(POCs)are soluble molecules in common organic solvents that provide significant potential for homogeneous ***,we report a triphenylphosphine‐derived quasi‐porous organic cage(denoted as POC‐DICP)as an efficient organic molecular cage ligand for Rh/PPh_(3) system‐catalyzed homogeneous hydroformylation ***‐DICP not only displays enhanced hydroformylation selectivity(aldehyde selectivity as high as 97%and a linear‐to‐branch ratio as high as 1.89)but can also be recovered and reused via a simple precipitation method in homogeneous reaction *** speculate that the reason for the high activity and good selectivity is the favorable geometry(cone angle=123.88°)and electronic effect(P site is relatively electron‐deficient)of POC‐DICP,which were also demonstrated by density functional theory calculations and X‐ray absorption fine‐structure characterization.