The specific roles played by both support and noble metals in light absorption, charge separation, and the formation of ·OH and O₂⁻ (ROS) are analyzed for light-triggered oxidation of phenol (Ph) over pristine and over noble metal (Ag, Au, Pt) -loaded TiO₂. Experiments show that the supported noble metals act as a light visible absorber, assist the separation of photo-charges and reduction of O₂ to O₂⁻. The O₂⁻ oxidizes mildly Ph to oxygenated products (hydroquinone, benzoquinone, and 1,2-dihydroxibenzene). In a parallel process, ·OH radicals, yielded by TiO₂, mineralize Ph to CO₂ by fast reaction sequences. Radical quenching and photo electrochemical measurements (surface photovoltage) confirm independently that the production of ·OH and O₂⁻ scale with oxidative conversion of Ph. The selectivity to CO₂ and mild oxidation products is the result of the interplay between catalyst activity for ·OH and for O₂⁻ production.

This paper presents the synthesis of La₂Ti₂O₇ nanoparticles by the sol–gel method starting from lanthanum nitrate and titanium alkoxide (noted as LTA). Subsequently, the lanthanum titanium oxide nanoparticles are modified with noble metals (platinum) using the chemical impregnation method, followed by a reduction process with NaBH₄. The comparative analysis of the structure and surface characteristics of the nanopowders subjected to thermal treatment at 900 °C is conducted using Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), ultraviolet-visible (UV–Vis) spectroscopy, as well as specific surface area and porosity measurements. The photocatalytic activity is evaluated in the oxidative photodegradation of ethanol (CH₃CH₂OH) under simulated solar irradiation. The modified sample shows higher specific surfaces areas and improved photocatalytic properties, proving the better conversion of CH₃CH₂OH than the pure sample. The highest conversion of ethanol (29.75%) is obtained in the case of LTA-Pt after 3 h of simulated solar light irradiation.

A multi-step ion-exchange methodology was developed for the fabrication of Cu(LaTa₂O₇)₂ lamellar architectures capable of wastewater depollution. The (001) diffraction line of RbLaTa₂O₇ depended on the guest species hosted by the starting material. SEM and TEM images confirmed the well-preserved lamellar structure for all intercalated layered perovskites. The UV–Vis, XPS, and photocurrent spectroscopies proved that Cu intercalation induces a red-shift band gap compared to the perovskite host. Moreover, the UV–Vis spectroscopy elucidated the copper ions environment in the Cu-modified layered perovskites. H₂-TPR results confirmed that Cu species located on the surface are reduced at a lower temperature while those from the interlayer occur at higher temperature ranges. The photocatalytic degradation of phenol under simulated solar irradiation was used as a model reaction to assess the performances of the studied catalysts. Increased photocatalytic activity was observed for Cu-modified layered perovskites compared to RbLaTa₂O₇ pristine. This behavior resulted from the efficient separation of photogenerated charge carriers and light absorption induced by copper spacer insertion.