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Exploring unique single‐atom sites capable of efficiently reducing O2 to H2O2 while being inert to H2O2 decomposition under light conditions is significant for H2O2 photosynthesis, but it remains challenging. Herein, we report the facile design and fabrication of polymeric carbon nitride (CN) decorated with single‐Zn sites that have tailorable local coordination environments, which is enabled by utilizing different Zn salt anions. Specifically, the O atom from acetate (OAc) anion participates in the coordination of single‐Zn sites on CN, forming asymmetric Zn−N3O moiety on CN (denoted as CN/Zn−OAc), in contrast to the obtained Zn−N4 sites when sulfate (SO4) is adopted (CN/Zn−SO4). Both experimental and theoretical investigations demonstrate that the Zn−N3O moiety exhibits higher intrinsic activity for O2 reduction to H2O2 than the Zn−N4 moiety. This is attributed to the asymmetric N/O coordination, which promotes the adsorption of O2 and the formation of the key intermediate *OOH on Zn sites due to their modulated electronic structure. Moreover, it is inactive for H2O2 decomposition under both dark and light conditions. As a result, the optimized CN/Zn−OAc catalyst exhibits significantly improved photocatalytic H2O2 production activity under visible light irradiation. [ABSTRACT FROM AUTHOR]

This paper proposes a new topology optimization formulation for obtaining shape memory alloy actuators which are designed with prescribed two-way transforming shapes. The actuation behaviors of shape memory alloy structures are governed by austenite-martensite phase transformations effected by thermal-mechanical loading processes; therefore, to realize the precise geometric shape variations of shape memory alloy actuators, traditional methods involve iteration processes including heuristic structural design, numerical predictions and experimental validation. Although advanced structural optimization methods such as topology optimization have been used to design three-dimensional (3D) shape memory alloy actuators, the maximization/minimization of quantities such as structural compliance or inaccurate stroke distances has usually been selected as the optimization objective to obtain feasible solutions. To bridge the gap between precise shape-morphing requirements and efficient shape memory alloy actuator designs, this paper formulates optimization criteria with quantitatively desired geometric shapes, and investigates the automatic designs of two-way prescribed shape morphing shape memory alloy structures based on the proposed topology optimization method. The super element method and adjoint method are used to derive the analytical sensitivities of the objective functions with respect to the design variables. Numerical examples demonstrate that the proposed method can obtain 3D actuator designs that have the desired two-way transforming shapes. [ABSTRACT FROM AUTHOR]

Developing highly efficient catalytic sites for O2 reduction to H2O2, while ensuring the fast injection of energetic electrons into these sites, is crucial for artificial H2O2 photosynthesis but remains challenging. Herein, we report a strongly coupled hybrid photocatalyst comprising polymeric carbon nitride (CN) and a two‐dimensional conductive Zn‐containing metal–organic framework (Zn‐MOF) (denoted as CN/Zn‐MOF(lc)/400; lc, low crystallinity; 400, annealing temperature in °C), in which the catalytic capability of Zn‐MOF(lc) for H2O2 production is unlocked by the annealing‐induced effects. As revealed by experimental and theoretical calculation results, the Zn sites coordinated to four O (Zn‐O4) in Zn‐MOF(lc) are thermally activated to a relatively electron‐rich state due to the annealing‐induced local structure shrinkage, which favors the formation of a key *OOH intermediate of 2e− O2 reduction on these sites. Moreover, the annealing treatment facilitates the photoelectron migration from the CN photocatalyst to the Zn‐MOF(lc) catalytic unit. As a result, the optimized catalyst exhibits dramatically enhanced H2O2 production activity and excellent stability under visible light irradiation. [ABSTRACT FROM AUTHOR]

Vanadium based compounds are promising cathode materials for aqueous zinc (Zn)‐ion batteries (AZIBs) due to their high specific capacity. However, the narrow interlayer spacing, low intrinsic conductivity and the vanadium dissolution still restrict their further application. Herein, we present an oxygen‐deficient vanadate pillared by carbon nitride (C3N4) as the cathode for AZIBs through a facile self‐engaged hydrothermal strategy. Of note, C3N4 nanosheets can act as both the nitrogen source and pre‐intercalation species to transform the orthorhombic V2O5 into layered NH4V4O10 with expanded interlayer spacing. Owing to the pillared structure and abundant oxygen vacancies, both the Zn2+ ion (de)intercalation kinetics and the ionic conductivity in the NH4V4O10 cathode are promoted. As a result, the NH4V4O10 cathode delivers exceptional Zn‐ion storage ability with a high specific capacity of about 370 mAh g−1 at 0.5 A g−1, a high‐rate capability of 194.7 mAh g−1 at 20 A g−1 and a stable cycling performance of 10 000 cycles. [ABSTRACT FROM AUTHOR]

To rationally design photocatalysts with high generation rate and selectivity of target product remains an ongoing challenge for CO2 conversion in pure H2O. Herein, from the viewpoint of enhancing the separation efficiency of photoinduced electron‐hole pairs and the adsorption ability of CO2 molecule, we have constructed a series of Z‐scheme defective heterojunctions of BiOBr nanosheets and hollow NH2‐functionalized metal‐organic framework (MOF) MIL‐125 with Ti ions as metal centers (noted as NH2‐MIL‐125(Ti)). Systematic characterization demonstrates that the BiOBr nanosheets are anchored on the surface of hollow NH2‐MIL‐125(Ti), which facilitates the efficient visible‐light‐driven catalytic reduction of CO2 to CO with nearly 100% selectivity by pure H2O. Especially, the CO generation rate of optimized catalyst with oxygen vacancies reaches 459.7 μmol g−1 h−1, which is higher than those of all the previously reported photocatalysts without sacrificial reagents. This approach provides a new insight for using inorganic semiconductors to fabricate semiconducting MOFs for high‐efficiency photocatalytic reduction CO2 into value‐added chemicals by pure H2O. [ABSTRACT FROM AUTHOR]

A new design method of the dual‐band balanced bandpass filter (BPF) using multilayer packaging dual‐mode substrate integrated waveguide (SIW) cavities is proposed. Split‐type coupling topology based on dual‐mode resonators is developed for the design. Firstly, a single‐band balanced filter with perturbed metal vias is designed. The TE201 mode and the TE202 mode perturbed by the metal vias can form a passband. Secondly, an additional metal vias perturbed SIW cavity with the same dual‐mode is placed in the lower layer for the bandstop function. A dual‐band balanced BPF with split‐type coupling topology is successfully realised. Compared with the traditional cascaded single‐mode form, the proposed dual‐mode split‐type design has more compact size and can be more easily extended to multi‐passbands. To verify the proposed method, a dual‐band balanced filter operating at 13.3 and 14.2 GHz is designed, fabricated and measured. The designed dual‐band balanced filter has good filtering performance including differential mode passband transmission and common mode rejection. Measured results show good agreements with simulated ones. [ABSTRACT FROM AUTHOR]

Serrations in the stress-time curve for a bulk metallic glass composite with microscale crystalline precipitates were measured with exceptionally high temporal resolution and low noise. Similar measurements were made for a more brittle metallic glass that did not contain crystallites but that was also tested in uniaxial compression. Despite significant differences in the structure and stress-strain behavior, the statistics of the serrations for both materials follow a simple mean-field model that describes plastic deformation as arising from avalanches of slipping weak spots. The presence of the crystalline precipitates reduces the number of large slips relative to the number of small slips as recorded in the stress-time data, consistent with the model predictions. The results agree with mean-field predictions for a smaller weakening parameter for the composite than for the monolithic metallic glass; the weakening parameter accounts for the underlying microstructural differences between the two. [ABSTRACT FROM AUTHOR]

Owing to the dissipative phase transformation and the porosity characteristics, cellular shape memory alloy (SMA) shows high damping capacity and thereby superior performance in vibration control. This paper studies the damping capacity and vibration behavior of the cellular SMA by means of the unit-cell finite element method. A material model of dense SMA is employed to simulate the thermodynamic behavior of the cellular SMA. A loss factor ω is introduced to evaluate the damping capacity of cellular SMA in a successive loading-unloading cycle. The effects of the material properties (the stress difference between the forward and reverse transformations, the saturated value of the transformation strain), the ambient temperature and the pore morphology (the porosity and the axial ratio of spheroid pore) on the damping capacity are investigated. Besides, the cellular SMA with randomly distributed pores is also considered. Simulation results well demonstrate the high damping capacity of the cellular SMA due to the local dissipative martensite phase transformation. Finally, by comparison of the free vibration behavior between the cellular SMA beam and the elastic beam, the cellular SMA exhibits superior performance in vibration control. [ABSTRACT FROM AUTHOR]