RESUMEN
High-performance production of green hydrogen gas is necessary to develop renewable energy generation technology and to safeguard the living environment. This study reports a controllable engineering approach to tailor the structure of nickel-layered double hydroxides via doped and absorbed platinum single atoms (PtSA) promoted by low electronegative transition metal (Mn, Fe) moieties (PtSA-Mn,Fe-Ni LDHs). We explore that the electron donation from neighboring transition metal moieties results in the well-adjusted d-band center with the low valence states of PtSA(doped) and PtSA(ads.), thus optimizing adsorption energy to effectively accelerate the H2 release. Meanwhile, a tailored local chemical environment on transition metal centers with unique charge redistribution and high valence states functions as the main center for H2O catalytic dissociation into oxygen. Therefore, the PtSA-Mn,Fe-Ni LDH material possesses a small overpotential of 42 and 288 mV to reach 10 mA·cm-2 for hydrogen and oxygen evolution, respectively, superior to most reported LDH-based catalysts. Additionally, the mass activity of PtSA-Mn,Fe-Ni LDHs proves to be 15.45 times higher than that of commercial Pt-C. The anion exchange membrane electrolyzer stack of PtSA-Mn,Fe-Ni LDHs(+,-) delivers a cell voltage of 1.79 V at 0.5 A·cm-2 and excellent durability over 600 h. This study presents a promising electrocatalyst for a practical water splitting process.
RESUMEN
This research designs a triphasic Ni2P-Ni12P5-Ru heterostructure with amorphous interface engineering strongly coupled by a cobalt nano-surface (Co@NimPn-Ru) to form a hierarchical 3D interconnected architecture. The Co@NimPn-Ru material promotes unique reactivities toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media. The material delivers an overpotential of 30 mV for HER at 10 mA cm-2 and 320 mV for OER at 50 mA cm-2 in freshwater. The electrolyzer cell derived from Co@NimPn-Ru(+,-) requires a small cell voltage of only 1.43 V in alkaline freshwater or 1.44 V in natural seawater to produce 10 mA cm-2 at a working temperature of 80 °C, along with high performance retention after 76 h. The solar energy-powered electrolyzer system also shows a prospective solar-to-hydrogen conversion efficiency and sufficient durability, confirming its good potential for economic and sustainable hydrogen production. The results are ascribed to the synergistic effects by an exclusive combination of multi-phasic crystalline Ni2P, Ni12P5, and Ru clusters in presence of amorphous phosphate interface attached onto cobalt nano-surface, thereby producing rich exposed active sites with optimized free energy and multi open channels for rapid charge transfer and ion diffusion to promote the reaction kinetics.
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The effects of the type of plasticizers and concentration of active substance on skin permeation properties of DHEA from patches were studied. The results showed that propylen glycol (as a plasticizer) could improve the skin permeation rate of DHEA significantly comparing with medium chain triglycerid. When the concentrations of DHEA in the patch increased, the skin permeation rates of DHEA increased linearly until DHEA solubility saturates in the matrix. But while the concentrations of DHEA in the patch were higher, DHEA could change in to the crystalline form that makes decreasing of the skin permeation rate of DHEA
Asunto(s)
Deshidroepiandrosterona , Preparaciones FarmacéuticasRESUMEN
PVP only does not enhance the solubility of DHEA but a combination effect will manifeste once the substance is used concurrently with HPCD. In 5,59% HPCD solution, this solubility was enhanced by 115 times and in 5,59% HPCD solution adding 0,1% PVP it was enhanced by 139 times. There is a strict interaction between its components, different evidently from the physical mixed graphic
Asunto(s)
Povidona , beta-Ciclodextrinas , AndrosteronaRESUMEN
Effects of HPCD and PVP in transdermal delivery systems prepared by combination of Eudragit E100, medium chain triglyceride and isopropyl alcohol on DHEA skin permeation properties were studied. The results were shown that HPCD and PVP have good effects both in permeation properties of DHEA in vitro through pig’s ear stratum corneum and the release properties of DHEA to skin surface. The highest permeation rate reported was about 3.88 mg/cm2.h that indicated the ability of using the patches as a dosage form for administration of DHEA