The most environmentally friendly protocol for obtaining mesoporous SiO₂–TiO₂catalysts has been sought.

Photocatalytic hydrogen production through ethanol photo-reforming using Na₂Ti₃O₇ whiskers increases if the sodium titanate is decorated with well-known metallic catalysts such as Ni and Pt. Whereas wet impregnation with nickel gives only a slight increase in the activity, photo-deposition of Pt increased the H₂ production by more than one order of magnitude. Through the combination of both co-catalysts (Ni and Pt) a superior performance in terms of H₂ production is further observed. However, hydrogen yield is largely enhanced (almost three-fold), up to 778 μmol·g⁻¹·h⁻¹, if the Pt is photo-deposited on the surface of the catalyst before wet impregnation with Ni species (NTO/Pt/Ni) compared to H₂ yield (283 μmol·g⁻¹·h⁻¹) achieved with the catalyst prepared in the reverse order (NTO/Ni/Pt). Structural, morphological, optical, and chemical characterization was carried out in order to correlate physicochemical properties with their photocatalytic activity. The X-ray photoelectron spectroscopy (XPS) results show a higher concentration of Pt²⁺ species if this metallic layer is under the nickel oxide layer. Moreover, X-ray diffraction patterns (XRD) show that Na₂Ti₃O₇ surface is modified for both metal decoration processes.

High purity metoprolol prepared by neutralization of an aqueous solution of metoprolol tartrate is efficiently mineralized to CO ₂ and water by photocatalysis with TiO ₂ , UV light and a constant flow rate of oxygen. Since the tartrate anions were eliminated, all the HO• generated by photocatalysis reacted efficiently with the aromatic part of the medication. The reaction pathway includes two routes of degradation. The first one includes the transformation of metoprolol to hydroquinone via formation of 4-(2-methoxyethyl)phenol, 2-(4-hydroxyphenyl)ethanol and 4-hydroxybenzaldehyde. Metoprolol is also degraded directly to hydroquinone. Then, this aromatic compound is oxidized to 1,2,4-benzenetriol, which is rapidly oxidized to low molecular weight organic acids before being completely mineralized to CO ₂ and water. Kinetic studies indicated that the initial reaction rate of the degradation of metoprolol, 4-(2-methoxyethyl)phenol, 2-(4-hydroxyphenyl)ethanol and 4-hydroxybenzaldehyde is described by the LH-HW model.