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A cyano-based DCI additive induces phase-buffering during the crystallization growth process of 2D halide perovskites, which effectively suppresses interphase strain, enhances lattice orientation and reduces trap-state density, delivering an outstanding and stable efficiency of ∼17.0% (n = 4).

Rhenium(I)-carbonyl-diimine complexes are promising photocatalysts for CO2 reduction. Covalent organic frameworks (COFs) can be perfect sensitizers to enhance the reduction activities. Here we investigated the excited state dynamics of COF (TpBpy) with 2,2'-bipyridine incorporating Re(CO)5Cl (Re-TpBpy) to rationalize the underlying mechanism. The time-dependent DFT calculation first clarified excited state structure of the hybrid catalyst. The studies from transient visible and infrared spectroscopies revealed the excitation energy-dependent photo-induced charge transfer pathways in Re-TpBpy. Under low energy excitation, the electrons at the LUMO level are quickly injected from Bpy into ReI center (1–2 ps) followed by backward recombination (13 ps). Under high energy excitation, the hot-electrons are first injected into the higher unoccupied level of ReI center (1–2 ps) and then slowly relax back to the HOMO in COF (24 ps). There also remains long-lived free electrons in the COF moiety. This explained the excitation energy-dependent CO2 reduction performance in our system.

Rechargeable aqueous zinc-ion battery (ZIB) is considered as a promising energy storage device due to the low cost, high obtainable output voltage, non-toxicity, and environmental friendliness. To achieve an excellent energy storage performance, morphology engineering of cathode materials for aqueous ZIBs is regarded as an important strategy. The impact of dimension and orientation of the cathode material on the electrochemical performance are, however, less studied. Herein, we compare two types of zinc pyrovanadate (Zn3V2O7(OH)2•2H2O, ZnVO) in nanowires and nanoflakes with the same crystal type but different orientations. ZnVO nanowires expose mostly the (001) plane lattice, in contrast to (020) and (110) lattice for ZnVO flakes. Interestingly, nanowires exhibit an excellent specific discharge capacity of 108 mAh g−1 after 700 cycles at 2 A g−1, contributed from Faradic and diffusion-controlled capacity. In contrast, nanoflakes deliver a very poor capacity of 1.5 mAh g−1 after 700 cycles at 0.1 A g−1 with only diffusion-controlled capacity. Density functional theory (DFT) reveals significantly different Zn2+ ion diffusion rates in ZnVO along different orientations.

Metal–organic frameworks (MOFs) as a class of crystalline porous solids have attracted considerable attention due to their promising potential performance. MOFs have been recently proved to be ideal sacrificial templates for fabricating their respective derivatives by changing the thermal conditions. However, uncertainties still remain, and the direct observation of transition from MOF to metal nanoparticles (NPs) dispersed in carbon matrix is an important and crucial task for the development of MOF-derived materials. Here, transmission electron microscopy (TEM) combined with in situ hot stage technique was applied to directly observe the transition from MOF to metal NPs. Through in situ TEM experiment, the nanocrystals of Ni–ntca precursor (ntca = 1,4,5,8-naphthalenetetra carboxylic acid) are pyrolyzed under the temperature of 400, 500, or 600 °C to synthesize abundant Ni-NPs embedded in hierarchically porous carbon composites. Furthermore, the as-prepared samples show high catalytic activity and stability for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with NaBH4 in aqueous conditions. More importantly, Ni@C-600, which has nickel contents of 72.8%, shorten the reduction time to 3.5 min with high conversion of nearly 100%. When the catalyst is applied to recycle after being separated from the reaction by an extern magnet, it still keeps high conversion of 92% after 8 cycles, addressing the high stability of the composites. It is believed that these results will further facilitate the exploration of the technique of the TEM combined with in situ hot stage as a powerful tool in the carbonization of MOFs to obtain MOF-derived materials with different applications.

Covalent organic frameworks (COFs) are an emerging class of porous crystalline polymers with broad potential applications. So far, the availability of three-dimensional (3D) COFs is limited and more importantly only one type of covalent bond has been successful used for 3D COF materials. Here, we report a new synthetic strategy based on dual linkages that leads to 3D COFs. The obtained 3D COFs show high specific surface areas and large gas uptake capacities, which makes them the top COF material for gas uptake. Furthermore, we demonstrate that the new 3D COFs comprise both acidic and basic sites, and act as excellent bifunctional catalysts for one-pot cascade reactions. The new synthetic strategy provides not only a general and versatile approach to synthesize 3D COFs with sophisticated structures but also expands the potential applications of this promising class of porous materials.