Motivating borate doped FeNi layered double hydroxides by molten salt method toward efficient oxygen evolution.

The incorporation of borate is a beneficial strategy to improve the catalytic activity of transition metal-based electrocatalyts for oxygen evolution reaction (OER). However, how to efficiently introduce borate has always been a challenge. Here, a facile and scalable molten salt method is developed to successfully dope borate into FeNi layered double hydroxides (FeBi@FeNi LDH) for efficient OER. The molten salt method can not only promote the formation of evenly dispersed nano-pompous FeBi precursor, thus providing the possibility to realize the direct doping of borate and the increase of mass, charge transfer and oxygen evolution active sites in FeNi LDH, but also promote the in-situ growth of FeBi@FeNi LDH on the conductive iron foam, improvingconductivity and stability of the material. The results indicate that the synthesized FeBi@FeNi LDH shows enhanced OER activity by delivering current densities of 10 and 100 mA cm-2 at low overpotentials of 246 and 295 mV and showing a small Tafel slope of 56.48 mV dec-1, benefiting from the optimization of geometric structure of active sites as well as the adjustment of electron density by borate doping especially in the case of molten salt. In addition, the sample can maintain durability at an industrial current density of 100 mA cm-1 for 90 h. This work provides a new way for the construction of efficient catalysts using boron doping assisted by molten salt.

Ultrahigh activity of molybdenum/vanadium-doped Ni-Co phosphides nanoneedles based on ion-exchange for hydrogen evolution at large current density.

Heteroatom doping is a promising strategy to optimize the electronic structure of transition metal phosphides so enhancing the hydrogen evolution reaction (HER). However, complex and harsh experimental design is often required to achieve homogeneous doping of corresponding elements while achieving the best regulating effect. Herein, a facile ion-exchange (IE) strategy is applied to dope Mo/V species evenly into Ni-Co phosphides under mild conditions while maintaining the nanoneedle morphology. The electrochemical characterization verifies Mo dopants have a better electronic regulation effect on NiCoP crystal than V dopants, corresponding to the better hydrogen evolution performance of Mo-NiCoP/NF. Notably, due to the highly dispersed nanoneedle morphology, the synergistic effect of Ni-Co phosphides, and the optimized electronic structure, Mo-NiCoP/NF demonstrates a higher activity than that of the noble metal Pt/C at the high current density (>99 mA cm-2). The present work is supposed to open new sights for the development of high-performance catalysts by ion-exchange strategy.

Yap1-2 Isoform Is the Primary Mediator in TGF-ß1 Induced EMT in Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is the most aggressive human malignancy and intrinsically resistant to conventional therapies. YAP1, as a key downstream effector of the Hippo pathway, plays an important role in tumorigenesis including PDAC. Alternative mRNA splicing of YAP1 results in at least 8 protein isoforms, which are divided into two subgroups (YAP1-1 and YAP1-2) based on the presence of either a single or double WW domains. We investigated the functions and regulatory mechanisms of YAP1-1 and YAP1-2 in PDAC cells induced by TGF-ß to undergo epithelial-to-mesenchymal transition (EMT). CRISPR-Cas9 and shRNA were used to silence YAP1 expression in pancreatic cancer cells. Re-constituted lentivirus mediated overexpression of each single YAP1 isoform was generated in the parental knockout L3.6 cells. EMT was induced by treatment with TGF-ß, EGF and bFGF in parental and the constructed stable cell lines. Western blot and qPCR were used to detect the expression of EMT markers. Scratch wound healing and transwell assays were used to detect cell migration. The stability and subcellular localization of YAP1 proteins were determined by Western blot analysis, immunofluorescence, as well as ubiquitination assays. We showed that TGF-ß, EGF and bFGF all significantly promoted EMT in PDAC cells, which was inhibited by knockdown of YAP1 expression. Interestingly, YAP1-1 stable cells exhibited a stronger migratory ability than YAP1-2 cells under normal culture condition. However, upon TGF-ß treatment, L3.6-YAP1-2 cells exhibited a stronger migratory ability than L3.6-YAP1-1 cells. Mechanistically, TGF-ß treatment preferentially stabilizes YAP1-2 and enhances its nuclear localization. Furthermore, TGF-ß-induced EMT and YAP1-2 activity were both blocked by inhibition of AKT signaling. Our results showed that both YAP1-1 and YAP1-2 isoforms are important mediators in the EMT process of pancreatic cancer. However, YAP1-2 is more important in mediating TGF-ß-induced EMT, which requires AKT signaling.

Modulation engineering of in situ cathodic activation of FePx based on W-incorporation for the hydrogen evolution reaction.

In situ electrochemical activation as a new pretreating method to adjust electrocatalytic performance attracts extensive attention. However, the activation mechanisms of electrocatalysts are still ambiguous. Herein, we propose a facile modulation strategy of in situ cathodic activation of FePx based on W-incorporation (W-FePx/IF) for the hydrogen evolution reaction (HER). The activated W-FeOx with obvious surface reconstruction demonstrates the role of W-incorporation for driving the cathodic activation of FePx, which suggests the larger surface area and more active sites. In fact, W incorporation can not only accelerate the cathodic activation process but also act as the adsorption sites for Had to form the synergistic effect with FeOx for water dissociation. The obtained W-FeOx/IF exhibits greatly enhanced HER activity featuring decreased overpotential from 237.7 to 154.0 mV at 100 mA cm-2, which may be ascribed to W-FeOx with double catalytic active sites after cathodic activation. Additionally, the modulation effects of cathodic activation can be exactly achieved by changing electrochemical parameters such as CV cycles. W-FeOx/IF also shows excellent long-term stability for at least 100 h at 100 mA cm-2. This modulation engineering based on metal doping is expected to provide inspiration for the understanding of the cathodic activation process for efficient electrocatalysts.

Surface construction of loose Co(OH)2 shell derived from ZIF-67 nanocube for efficient oxygen evolution.

The rational design of nanostructure is very important for improving the number and effective utilization of active sites of the electrocatalysts. Here, a core-shell nanostructure composed of ZIF-67 core and Co(OH)2 shell (ZIF-67@Co(OH)2) has been obtained by subjecting ZIF-67 nanocube to the optimal high temperature etching process. After refluxing and etching in ethanol/water mixed solution, the loose Co(OH)2 shell can be constructed based on the surface of etched ZIF nanocube, which provides the obviously abundant active cobalt sites and better contact for oxygen evolution reaction (OER). Compared to the whole hollow Co(OH)2 nanocube, the solid ZIF-67 core in ZIF-67@Co(OH)2 can be favorable for charge transfer and provide the stable structure. The synergistic effect between Co(OH)2 shell and ZIF-67 core under suitable etching regulation can realize the optimized electrocatalysis for OER. The performance measurements show that Co(OH)2-1 after refluxing 1 h demonstrates the excellent activity requiring 354 mV overpotential at the current density of 10 mA cm-2 and the good stability. The enhanced mechanism may be due to the formation of loose Co(OH)2 as shell with fully exposed active sites, as well as the synergistic effect between ZIF-67 core and Co(OH)2 shell. Therefore, the surface construction of active composites based on ZIF precursor may be a new strategy for efficient electrocatalysis for water splitting.