It is well-documented that large-scale pollution generated by human activity has a dramatic impact on ecosystems. In this context, removing harmful chemicals via photocatalysis has tremendous potential as a depollution method, utilizing freely available solar light and catalytic materials with low or negligible ecotoxicity. The main drawbacks, which aren’t often addressed in the available literature, are the formation of harmful intermediate products, low reaction rates, limited catalyst stability, and difficult catalyst recovery. In most cases, published works assess the efficiency of tested photocatalysts from pollutant degradation studies, whereas identifying and quantifying by-products is not often conducted. This review summarizes the recent advances reported for the photocatalytic removal of some organic (e.g., alcohols, carboxylic acids, volatile organic compounds, phenol) and inorganic (e.g., NO₃⁻) contaminants. The efficiency of various UV- and visible-light active photocatalysts and the reaction degradation pathways were explained, emphasizing the main factors contributing to their mineralization. The reaction mechanisms, the identification and quantification of degradation intermediates, and the implication of reactive active species (ROS) were discussed and analyzed for each category of model target pollutant. Additionally, the actual challenges and future photocatalytic approaches to improve environmental remediation were presented.

The electrochemical behavior at room temperature in a neutral sodium chloride aqueous solution of four types of metallorganic chemical vapor deposited aluminum oxide coatings on commercial Ti6242 titanium alloy was investigated. Polarization and electrochemical impedance curves revealed that porosity free, amorphous alumina coatings provide a two order of magnitude improvement of the corrosion resistance with regard to the bare alloy. Crystallized alumina as well as amorphous AlO(OH) only slightly improve the corrosion resistance of Ti6242. It was demonstrated that metallorganic chemical vapor deposition processed amorphous alumina is a highly promising solution to the protection of titanium alloys against corrosion in salt environments.

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.