Developing efficient metal−organic framework (MOF)-based electrocatalysts with improvable activity and persistence toward the methanol oxidation reaction (MOR) is attracting great research attention but still remains an enormous challenge. Herein, a facile strategy, hydrangea-shaped nickel hydroxide template-directed synthesis of the hierarchically structured Ni-MOF on the Ni(OH) 2 heterocomposite (denoted as Ni−Ni) for efficient MOR, is developed. The unique hierarchical structure and synergistic effect of the heterocomposite afford more exposed active sites, a facile ion diffusion path, and improved conductivity, favorable for improving MOR catalytic performance. Remarkably, the optimized Ni−Ni-2 material delivers an excellent activity with a high peak current density (24.6 mA cm −2 ). Furthermore, to prove the universality of this strategy, Ni x Cu 1−x (OH) 2 isometallic hydroxide was used as the precursor, and a series of MOF-74/Cu x Ni 1−x (OH) 2 (denoted as Ni−NiCu) heterogeneous materials have been prepared and could be used as an effective electrocatalyst to catalyze MOR. The results indicate that this strategy can be used in the synthesis of other new composite materials with specific hierarchical structures for a more efficient electrocatalytic system.

Developing high-efficiency and cost-effective electrocatalytic oxygen evolution reaction (OER) catalysts would determine the future distributions of energy conversion technologies. Metal–organic frameworks (MOFs), with unsaturated active metal sites, functionalized organic linkers, and large surface areas, are emerging heterogeneous electrocatalysts for the water oxidation process. Herein, we report an oxygen-evolving microporous (3,10)-connected Co6-based MOF (denoted as CTGU-14) for the electrocatalytic OER. Moreover, the integration of Co-MOF and SnO2, SnO2 (15%) & CTGU-14 composite attains remarkable electrochemical OER performance with a small Tafel slope of 68 mV·dec–1, a positive overpotential of 388 mV at 10 mA·cm–2, and overall durability in an alkali medium. The superior OER activities might be ascribed to more convenient electron transfer from the SnO2 additive to the electrode medium, effective surface area and unsaturated active cobalt centers, and more beneficial delivery for hydroxy radicals in the microporous Co-MOF skeleton in the process of the OER.

Understanding the active species derived from metal− organic frameworks (MOFs) plays a vital role in the fabrication of highly efficient and stable oxygen evolution reaction (OER) electrocatalysts. Herein, a new alkaline-stable 3D nickel metal−organic framework (Ni-MOF), containing a 1D rod-packing chain structure fused with a tetranuclear nickel cluster [Ni 4 (μ 3 -OH) 2 ], is used as a target material to explore its OER properties. The electrocatalytic activities of pure Ni-MOF and hybrid materials made from Ni-MOF with different acetylene black loaded electrodes, such as glassy carbon, fluorine-doped tin oxide, and nickel foam, have been evaluated. Further analysis unravels that the enhanced OER performance might be attributed to the synergistic interactions of two catalytic active species between in situ formed β-Ni(OH) 2 and a tetranuclear Ni 4 (μ 3 -OH) 2 cluster in Ni-MOF. The findings will shed fresh light on the fabrication of MOF-derived catalysts for efficient electrochemical energy conversion.

BACKGROUNDEctopic expression of miRNAs promotes tumor development and progression. miRNA (miR)-320a is downregulated in many cancers, including gastric cancer (GC). However, the mechanism underlying its downregulation and the role of miR-320a in GC are unknown.AIMTo determine expression and biological functions of miR-320a in GC and investigate the underlying molecular mechanisms.METHODSQuantitative real-time polymerase chain reaction (PCR) was used to determine expression of miR-320a in GC cell lines and tissues. TargetScanHuman7.1, miRDB, and microRNA.org were used to predict the possible targets of miR-320a, and a dual luciferase assay was used to confirm the findings. Western blotting was used to detect the protein levels of pre-B-cell leukemia homeobox 3 (PBX3) in GC cells and tissue samples. Cell Counting Kit-8 proliferation, Transwell, wound healing, and apoptosis assays were performed to analyze the biological functions of miR-320a in GC cells. Methylation-specific PCR was used to analyze the methylation level of the miR-320a promoter CpG islands. 5-Aza-2’-deoxycytidine (5-Aza-CdR) and trichostatin A (TSA) were used to treat GC cells.RESULTSmiR-320a expression was lower in GC cell lines and tissues than in the normal gastric mucosa cell line GES-1 and matched adjacent normal tissues. miR-320a overexpression suppressed GC cell proliferation, invasion and migration, and induced apoptosis. PBX3 was a target of miR-320a in GC. The methylation level of the miR-320a promoter CpG islands was elevated and this was partly reversed by 5-Aza-CdR and TSA.CONCLUSIONmiR-320a acts as a tumor suppressor and inhibits malignant behavior of GC cells, partly by targeting PBX3. DNA methylation is an important mechanism associated with low expression of miR-320a.

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