Synthesis of MOFs and Their Composite Structures through Sacrificial-Template Strategy

Exemplified by chemical conversion of ZnO nanostructures into zeolitic imidazolate framework-8 (ZIF-8) nanostructures, a sacrificial-template method has been demonstrated for the synthesis of metal–organic frameworks (MOFs) and their composite structures which may not be attainable by other methods. Their properties were investigated and the formation mechanism of ZIF-8 nanostructures was discussed. This method shows the potential of the formation of various-shaped MOFs and their composite nanostructures and will broad the applications of MOFs and their derivatives

Vapor–Liquid–Solid Growth of Endotaxial Semiconductor Nanowires

Free-standing and in-plane lateral nanowires (NWs) grown by the vapor–liquid–solid (VLS) process have been widely reported. Herein, we demonstrate that the VLS method can be extended to the synthesis of horizontally aligned semiconductor NWs embedded in substrates. Endotaxial SiGe NWs were grown in silicon substrates by tuning the directional movement of the catalyst in the substrates. The location of the SiGe NWs can be controlled by the SiO₂ pattern on the silicon surface. By varying the growth conditions, the proportion of Ge in the obtained NWs can also be tuned. This approach opens up an opportunity for the spatial control of the NW growth in substrates and can potentially broaden the applications of NWs in new advanced fields

Interdiffusion Reaction-Assisted Hybridization of Two-Dimensional Metal–Organic Frameworks and Ti₃C₂T_<i>x</i> Nanosheets for Electrocatalytic Oxygen Evolution

Two-dimensional (2D) metal–organic framework (MOF) nanosheets have been recently regarded as the model electrocatalysts due to their porous structure, fast mass and ion transfer through the thickness, and large portion of exposed active metal centers. Combining them with electrically conductive 2D nanosheets is anticipated to achieve further improved performance in electrocatalysis. In this work, we <i>in situ</i> hybridized 2D cobalt 1,4-benzenedicarboxylate (CoBDC) with Ti₃C₂T_<i>x</i> (the MXene phase) nanosheets <i>via</i> an interdiffusion reaction-assisted process. The resulting hybrid material was applied in the oxygen evolution reaction and achieved a current density of 10 mA cm^–2 at a potential of 1.64 V <i>vs</i> reversible hydrogen electrode and a Tafel slope of 48.2 mV dec^–1 in 0.1 M KOH. These results outperform those obtained by the standard IrO₂-based catalyst and are comparable with or even better than those achieved by the previously reported state-of-the-art transition-metal-based catalysts. While the CoBDC layer provided the highly porous structure and large active surface area, the electrically conductive and hydrophilic Ti₃C₂T_<i>x</i> nanosheets enabled the rapid charge and ion transfer across the well-defined Ti₃C₂T_<i>x</i>–CoBDC interface and facilitated the access of aqueous electrolyte to the catalytically active CoBDC surfaces. The hybrid nanosheets were further fabricated into an air cathode for a rechargeable zinc–air battery, which was successfully used to power a light-emitting diode. We believe that the <i>in situ</i> hybridization of MXenes and 2D MOFs with interface control will provide more opportunities for their use in energy-based applications