RESUMO
The charge separation/transport efficiency is relatively high in thin-film hematite photoanodes in which the distance for charge transport is short, but simultaneously the high loss of light absorption due to transmission is confronted. To increase light absorption in thin-film Fe2O3:Ti, commercial substrates such as Cu foil, Ag foil, and a mirror are adopted acting as back-reflectors and individually integrated with the Fe2O3:Ti electrode. The promotion effect of the commercial back-reflectors on the light absorption efficiency and photoelectrochemical (PEC) performance of the hydrothermally prepared Fe2O3:Ti electrodes with a variety of film thicknesses is investigated. As a result, Ag foil and the mirror show favorable and equal efficacy while the promoting effect of Cu foil is limited. In addition, the photocurrent increment achieved by the Ag back-reflector decreases linearly along with the logarithmic of the film thickness and the optimized film thickness of the Fe2O3:Ti electrode is decreased from 520 to 290 nm. The high durability of Ag foil in the alkaline electrolyte during solar light irradiation is demonstrated. Furthermore, the reflective substrate also shows a promotion effect on the BiVO4 photoanode and CuBi2O4 photocathode, as well as the unbiased photocurrent from a tandem cell constituted by TiO2 and CuBi2O4.
RESUMO
MOFs are typically synthesized under severe conditions that require high pressure and temperature. Accordingly, herein we necessitated advances in their expeditious and scalable synthesis at ambient conditions. In this aspect, the Cu-BDC and Cu-BTC can now be prepared in minutes via a controlled dissolution-crystallization route with divalent metal acetate as a precursor at room temperature, and would be highly desired for industrial implementation and commercialization.
RESUMO
In this work, we have developed a novel and facile method to prepare gallic acid-grafted chitosan/polysulfone (PS) composite membranes for dye removal from aqueous solutions. First, the gallic acid was grafted onto the eco-friendly chitosan through a free-radical grafting copolymerization reaction. Second, the gallic acid-grafted chitosan conjugates were codeposited onto the top surface of PS substrates by electrostatic interactions in order to transform the ultrafiltration membrane to the thin and defect-free nanofiltration membrane. The morphology and chemical composition of the as-prepared composite membranes were fully characterized by various spectroscopy and microscopy techniques. Moreover, after the optimization of preparation parameters, the obtained membrane displayed a high rejection of 97.2% for Congo red with a high permeance of 14.0 L h-1 m-2 bar-1. Furthermore, the composite membranes also exhibited good rejections for other dyes with different molecular weights such as Evan blue (97.3%), Acid red 94 (97.6%), and Alcian blue 8GX (98%) on the basis of size exclusion, accompanied with good permeance of 12.9, 11.9, and 10.9 L h-1 m-2 bar-1, respectively, which shows potential for scale-up industrial applications.
RESUMO
The material demand for metal organic framework (MOF) production necessitates advance in their expedient and scalable synthesis that can operate at room temperature which would be pivotal for chemical industry. Toward that end, M-Hoba, where M = divalent metal acetate and Hoba = 4,4'-oxybis(benzoic acid), can now be prepared in minutes via a controlled dissolution-crystallization route with divalent metal acetate as a precursor. MOFs prepared by this strategy were highly crystalline. This synthetic method was also applied successfully to the synthesis of a MOF-5 series (Cu) and Cu-BTC to highlight its generality. This method can move traditional MOF synthesis from the laboratory scale to the industrial scale.