RESUMEN
Ru-doped Co9S8 hollow porous polyhedrons (Ru-Co9S8 HPPs) derived from zeolitic-imidazolate-frameworks were synthesized through hydrothermal coprecipitation and thermal decomposition methods. The results indicate that Ru-Co9S8-500 HPPs possess a strong Ru-Co synergistic effect, large electrochemical surface area, and sufficient active sites, endowing them with excellent hydrogen evolution reaction performance.
RESUMEN
Transition metal oxides (TMOs) and their heterostructure hybrids have emerged as promising candidates for hydrogen evolution reaction (HER) electrocatalysts based on the recent technological breakthroughs and significant advances. Herein, Ru-Co oxides/Co3 O4 double-shelled hollow polyhedrons (RCO/Co3 O4 -350 DSHPs) with Ru-Co oxides as an outer shell and Co3 O4 as an inner shell by pyrolysis of core-shelled structured RuCo(OH)x @zeolitic-imidazolate-framework-67 derivate at 350 °C are constructed. The unique double-shelled hollow structure provides the large active surface area with rich exposure spaces for the penetration/diffusion of active species and the heterogeneous interface in Ru-Co oxides benefits the electron transfer, simultaneously accelerating the surface electrochemical reactions during HER process. The theory computation further indicates that the existence of heterointerface in RCO/Co3 O4 -350 DSHPs optimize the electronic configuration and further weaken the energy barrier in the HER process, promoting the catalytic activity. As a result, the obtained RCO/Co3 O4 -350 DSHPs exhibit outstanding HER performance with a low overpotential of 21 mV at 10 mA cm-2 , small Tafel slope of 67 mV dec-1 , and robust stability in 1.0 m KOH. This strategy opens new avenues for designing TMOs with the special structure in electrochemical applications.
RESUMEN
In this paper, an intensive and glow-type chemiluminescence (CL) hydrogel was prepared by simultaneous incorporation of chemiluminescence reagent (luminol) and catalytic cofactor (hemin) into the scaffold of guanosine-derived hydrogel. The self-assembled hydrogel consisted of K+ stabilized hemin/G-quartet structures, showing significant enzyme-like activity to H2O2-mediated oxidation of luminol. After adding H2O2 into the hydrogel, blue light visible to naked eyes would come into being and last for over 8 h. The lasting-time CL emission of hydrogel was achieved due to a mechanism of slow-diffusion-controlled heterogeneous catalysis. Moreover, this self-assembled hydrogel performed a good response to H2O2 and the CL emission images could be recorded by smartphone. The hydrogel could remain excellent lifetime stability for months and the stable, enhanced and glow-type CL emission could improve the reliability and precision of CL detection, which has a promising application in cold light source and H2O2 detection of real biological samples.
RESUMEN
Organic molecules and related nanomaterials have attracted extensive attention in the realm of electrochemiluminescence (ECL). Herein, a well-known electroluminescence (EL) dopant 2,3,6,7-tetrahydro-1,1,7,7,-tetramethyl-1H,5H,11H-10-(2-benzothiazolyl)quinolizino-[9,9a,1gh] coumarin (C545T) is selected as a new ECL illuminant, which shows a high photoluminescence quantum yield of nearly 100% and excellent ECL performance in the organic phase. For utilizing C545T to achieve ECL detection in aqueous solution, organic microrods of C545T (C545T MRs) were synthesized by a precipitation method. Cyclic voltammetry and differential pulse voltammetry of C545T and C545T MRs in acetonitrile or phosphate buffer showed one reduction and multiple oxidation peaks, suggesting that the multiple charge states of C545T could be produced by continuous electron- or hole-injection processes. The annihilated ECL emission of C545T and C545T MRs was observed using ECL transient technology. In the presence of triethanolamine (TEOA) or potassium persulfate (K2S2O8), C545T MRs can also give bright anodic and cathodic ECL emission at the GCE/water interface. The proposed ECL system not only has multichannel ECL emission but also shows intense yellow emission (569 nm) with a relative ECL efficiency of 0.81 when TEOA was used as a coreactant. Benefiting from the strong ECL emission of the C545T MRs/TEOA system and the quenching effect of dopamine (DA) on ECL, a convenient sensor for DA was developed with high selectivity and sensitivity.
RESUMEN
Cyclin-dependent kinase 5 (Cdk5) is a serine/threonine kinase that is activated by the neuron-specific activators p35/p39 and plays important roles in neuronal development, synaptic plasticity, and cognitive behavior. However, the proteolytic cleavage of p35 to p25 leads to prolonged and aberrant Cdk5 activation and results in synaptic depression, highly mimicking the early pathology of Alzheimer's disease (AD). Therefore, Cdk5 inhibition is a potential promising strategy for AD drug development. Here in the present study, we showed that metformin, the most widely used drug for type 2 diabetes, suppressed Cdk5 hyper-activation and Cdk5-dependent tau hyper-phosphorylation in the APP/PS1 mouse hippocampus. We also identified the underlying molecular and cellular mechanism that metformin prevented Cdk5 hyper-activation by inhibiting the calpain-dependent cleavage of p35 into p25. Moreover, chronic metformin treatment rescued the core phenotypes in APP/PS1 mice as evidenced by restored spine density, surface GluA1 trafficking, Long-term potentiation (LTP) expression, and spatial memory. Altogether our study discovered an unidentified role of metformin in suppressing Cdk5 hyper-activation and thus preventing AD pathogenesis and suggested that metformin is a potential promising AD therapeutic drug.
RESUMEN
SrRuO3 as a rare conductive perovskite ruthenate has attracted increasing attention for application in energy conversion. Here, the electrocatalytic activity for the hydrogen evolution reaction (HER) of thermally synthesized layered SrRuO3 is investigated and shows a considerable activation during cathodic polarization in alkaline solution. The analysis demonstrates the electrode activation is caused by the increased hydrophilicity of SrRuO3 surface, revealing the influence of the surface properties on HER performance. For further improving the catalytic activity of perovskite ruthenate, the RuO2 /SrRuO3 (RSRO) heterostructure is fabricated in situ by reducing the thermal decomposition temperature of 1000 °C for SrRuO3 to 600 °C. The appropriate lattice parameter of SrRuO3 ensures a good lattice match, which results in a strong interaction between SrRuO3 and RuO2 . Hence, the RSRO substantially outperforms the corresponding single-component oxides. In addition, the increased active sites induced by the rapid improvement of hydrophilicity of RSRO surface further highlight its structural advantage for catalytic hydrogen generation. The experimental and theoretical computation results consistently validate the positive synergistic effect among SrRuO3 and RuO2 in tuning the atomic and electronic configuration.
RESUMEN
Ru, RuO2 and MoO3 embedded carbon nanorods (Ru-RuO2/MoO3 CNRs) were synthesized through electrospinning and low-temperature calcination. Results of comprehensive characterizations suggest that the strong interaction between Ru and Mo species, large electrochemical surface area, and high electrical conductivity (a proper ratio of RuO2 to Ru) endow Ru-RuO2/MoO3 CNRs-350 with excellent hydrogen evolution reaction (HER) performance.
RESUMEN
A [Fe3O4/polyvinyl pyrrolidone (PVP)]//[Tb(BA)3phen/PVP] Janus nanofiber array pellicle (denoted JNAP) was successfully constructed by facile conjugate electrospinning without twisting for the first time. The JNAP offers the dual-functionality of fluorescence and magnetism. This technology entirely solves the dilemma of the magnetic spinning dope and fluorescent spinning dope being easily mixed together during the parallel electrospinning process, as it achieves complete segregation of magnetic nanoparticles and fluorescent molecules. Moreover, conjugate electrospinning without twisting has fewer requirements on the viscosity of the spinning dope compared with parallel electrospinning, in which the two spinning dopes should have the same viscosity. It was satisfactorily found that the JNAP has higher fluorescence intensity than the corresponding non-aligned Janus nanofiber pellicle. The magnetism of the JNAP could be tailored by changing the doping amount of the Fe3O4 NPs. The JNAP has potential applications in nanotechnology and biomedicine, etc., due to its enhanced green fluorescence and adjustable magnetism. In addition, this design concept and manufacturing process provide a facile way for preparing other one-dimensional Janus nanomaterials with multifunctionality.
