Titanium oxide was deposited on activated carbon (AC) in two forms, as powder and as a pellet. This oxide was obtained using sol–gel process based on titanium isopropoxide and isopropyl alcohol. Nanocrystalline TiO2 anatase phase on activated carbon was obtained using an adequated thermal treatment of 325 ¿C for 5 h considering the thermal instability of the AC. The resulting material was characterized by spectroscopic X-ray fluorescence, scanning electron microscopy with energy dispersive X-ray microanalyses (EDX), and Brunauer–Emmett–Teller (BET) surface area measurements. Activity measurements performed under UV lamp and solar irradiation have shown good results for the photo degradation of phenol in aqueous solution. For solar applications, a polyethylene terephtalate bottle containing the photocatalyts was filled up with the contaminated water and placed a few hours under the solar radiation for a couple of sunny days. The results indicate that 20 ppm of phenol can be removed by using this method.Indexado en ScopusRevisión por pare

Porous β-Bi₂O₃/Bi₂O₂CO₃ composite photocatalysts showed enhanced photocatalytic activities for degrading organic pollutants under visible light due to the p–n heterojunction.

The optoelectronic properties of hydrogenated amorphous silicon–carbon alloys (a‐SiC:H) are studied over the entire compositional range of carbon content. The films are prepared using radio‐frequency glow discharge and optimization was made with respect to deposition power and pressure, hydrogen dilution, and methane (or ethylene) ‐to‐silane gas phase ratio. Regardless of the deposition conditions and source gases used, the optical, structural, and transport properties of the a‐SiC:H alloys followed simple universal dependencies related to changes in the density of states associated with their structural disorder. The Urbach tail energy E_u and the B factor of the Tauc plot correlate with E₀₄ (defined as the energy at which the absorption coefficient is equal to 10⁴ cm⁻¹) taken from photothermal deflection spectroscopy measurements. Up to E₀₄^pds≊2.6 eV, E_u increases monotonically from 50 up to ≊200 meV, while the B factor decreases from ≊800 down to ≊200 cm^−1/2 eV^−1/2. Above E₀₄^pds≊2.6 eV, both E_u and B remain approximately constant. The photoconductivity decreases exponentially with E₀₄^pds and is below 10⁻¹⁰ Ω⁻¹ cm⁻¹ for E₀₄^pds≥2.6 eV. Room‐temperature photoluminescence is observed when E₀₄^pds≥2.6 eV. The photoluminescence peak position lies an average of 0.6 eV below the value of E₀₄^pds and increases linearly with decreasing value of the B factor of the Tauc plot.