Adsorption of Chromium(VI) Ions on to TiO from Aqueous Solution

The study of the adsorption of the Cr VI ion on to TiO 2 not only provides information on the removal of heavy metal ions from polluted aqueous solutions; but is also useful for further investigation of the photocatalytic decontamination of the Cr VI ion or of Cr VI –organic species which co-exist as pollutants with TiO 2 when the latter is used as a stable and highly efficient photocatalyst. It has been found that dark adsorption of the Cr VI ion on to TiO 2 is mainly dependent on the acidity of the system and the initial concentration of the Cr VI ion. As the pH of the system increases, so the extent of adsorption of the Cr VI ion decreases. The greatest adsorption was obtained with an initial Cr VI ion concentration of ca. 300 μmol/l. The presence of phosphate or acetate ions in the system dramatically decreases the adsorption efficiency of the Cr VI ion. In contrast, the addition of formic acid leads to a limited increase in the extent of Cr VI ion adsorption. Other organic ions and organic compounds examined showed no interference in Cr VI ion adsorption. FT-IR spectroscopic methods were used for the characterization of Cr VI ion adsorption on to TiO 2

Enhanced Electron Transfer from the Excited Eosin Y to mpg‑C₃N₄ for Highly Efficient Hydrogen Evolution under 550 nm Irradiation

Graphitic carbon nitride (g-C₃N₄) is a novel and stable metal-free photocatalyst that can generate H₂ from water under visible light irradiation, but its activity is significantly limited due to the insufficient light absorption in the solar spectrum (weak absorption in the wavelength longer than 460 nm). In this paper, we demonstrate that the photoresponse of the mesoporous g-C₃N₄ (mpg-C₃N₄) can be greatly extended up to nearly 600 nm by sensitization with Eosin Y (EY). This sensitization photocatalyst demonstrates high and rather stable photocatalytic activity for H₂ evolution under visible light irradiation, especially in the longer wavelength regions (450–600 nm). The apparent quantum efficiency (AQE) of 19.4% under 550 nm irradiation has been obtained. These results indicate that efficient electron transfer between excited EY molecules and mpg-C₃N₄ is achieved. The mpg-C₃N₄ with high surface area and nanoporous structure can greatly facilitate EY molecules assembly on the surface, thus promoting the activity via improved light harvesting

Catalytic wet oxidation of aqueous methylamine: comparative study on the catalytic performance of platinum–ruthenium, platinum, and ruthenium catalysts supported on titania

<div><p>Promotion of the dispersion of Ru species supported on TiO₂ was achieved by introduction of Pt component and the role of Pt in enhancing the catalytic performances of Pt–Ru was investigated with catalytic wet air oxidation of methylamine used as a probing reaction. It was found that Pt–Ru/TiO₂ displayed a much better catalytic performance compared with Pt/TiO₂ and Ru/TiO₂ catalysts due to having the highest dispersion of active species. Both high total organic carbon conversion and nitrogen selectivity (∼100%) over Pt–Ru/TiO₂ catalyst were achieved at low temperature (200 °C). X-ray photoelectron spectroscopy characterization indicated that there were strong interactions between metal particles and the support, which may increase the catalytic performance of catalysts.</p></div

Fivefold Enhanced Photoelectrochemical Properties of ZnO Nanowire Arrays Modified with C3N4 Quantum Dots

A facile and effective growing strategy of graphite-like carbon nitride quantum dots (CNQDs) modified on ZnO nanowire array composite electrodes has been successfully designed and prepared for the first time. The remarkable quantum enhanced properties were carefully studied by means of scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscope (XPS), UV-vis diffuse reflectance, PEC performance, and photocatalytic hydrogen production, and the results were in good agreement. Fivefold enhanced photoelectrochemical performances of this novel hierarchical hetero-array prepared in this paper compared with pure ZnO nanowire arrays were obtained under UV-light. The effect was attributed to the remarkable charge separation between CNQDs and ZnO nanowire arrays. Additional investigations revealed that the particular structure of CNQDs/ZnO composites contributed to the separation of a photon-generation carrier and an enhanced photoelectric current. Moreover, the absorption edge of CNQD-modified ZnO nanowire arrays was slightly broadened, and the diameter was reduced as well. The photoelectrochemistry hydrogen evolution splitting water using simulated solar irradiation exhibited the foreground of a possible application of a mechanism of photoelectrochemistry hydrogen evolution over CNQDs/ZnO composite electrodes