In this work, the optimization of Ni amount on LaFeO₃ photocatalyst was studied in the photocatalytic molecular hydrogen production from glucose aqueous solution under UV light irradiation. LaFeO₃ was synthesized via solution combustion synthesis and different amount of Ni were dispersed on LaFeO₃ surface through deposition method in aqueous solution and using NaBH₄ as reducing agent. The prepared samples were characterized with different techniques: Raman spectroscopy, UltraViolet-Visible Diffuse Reflectance Spettroscopy (UV–Vis-DRS), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), X-ray Fluorescence (XRF), Transmission Electron microscopy (TEM), and Scanning Electron microscopy (SEM) analyses. For all the investigated photocatalysts, the presence of Ni on perovskite surface resulted in a better activity compared to pure LaFeO₃. In particular, it is possible to identify an optimal amount of Ni for which it is possible to obtain the best hydrogen production. Specifically, the results showed that the optimal Ni amount was equal to nominal 0.12 wt% (0.12Ni/LaFeO₃), for which the photocatalytic H₂ production was equal to 2574 μmol/L after 4 h of UV irradiation. The influence of different of photocatalyst dosage and initial glucose concentration was also evaluated. The results of the optimization of operating parameters indicated that the highest molecular hydrogen production was achieved on 0.12Ni/LaFeO₃ sample with 1.5 g/L of catalyst dosage and 1000 ppm initial glucose concentration. To determine the reactive species that play the most significant role in the photocatalytic hydrogen production, photocatalytic tests in the presence of different radical scavengers were performed. The results showed that •OH radical plays a significant role in the photocatalytic conversion of glucose in H₂. Moreover, photocatalytic tests carried out with D₂O instead of H₂O evidenced the role of water molecules in the photocatalytic production of molecular hydrogen in glucose aqueous solution.

This work describes the application of three different AgBr heterojunctions with TiO₂, SnO₂ and WO₃ in the treatment of two water sources: wastewater from a dairy industry facility (WDI) and water from a polluted river (WPR). All heterojunctions were widely characterised, and it was observed that the physicochemical properties of all the coupled materials were similar; however, the highest elimination of Enterobacteriaceae (>90%) was obtained with the AgBr/WO₃(20%) photocatalyst in WDI. Under the same conditions, with this photocatalyst, the complete removal of bacteria (i.e., E. coli, total coliforms and other Enterobacteriaceae) was achieved in WPR. The chlorides, hardness and colour in the two water samples decreased after photocatalytic treatment with all the coupled materials. However, nitrate levels and chemical oxygen demand increased due to the possible formation of intermediary species from the photodegradation of organic pollutants and the release of metabolic intermediates from bacterial degradation during the photocatalytic process. Overall, heterogeneous photocatalysis based on AgBr-coupled materials shows potential as a tertiary treatment for WDI and for the purification of vegetable irrigation water. However, it is still important to consider the need to optimise the integrity of photocatalytic materials in order to maintain their bactericidal effectiveness through continuous reuse.

In this work, different materials based on TiO₂ coupled with either AgBr or Ag₃PO₄ were synthesized. The Ag₃PO₄(50%)/TiO₂ powder photocatalyst prepared by deposition–precipitation method showed higher antimicrobial activity than the bare TiO₂ and also than the same coupled powder obtained by sol–gel method. This material achieved 100% E. coli, coliforms, and other enterobacteria elimination. The high bactericidal efficiency of this material could be attributed to the improved properties obtained by coupling Ag₃PO₄ and TiO₂, such as high absorption in the visible region, low band-gap value, and high surface hydroxylation. The sol–gel method was chosen for the production of photocatalytic coatings on borosilicate glass tubes based on TiO₂ and Ag₃PO₄/TiO₂ materials due to the ease of its preparation procedure and its suitability for dip coating. In this series, the most effective elimination of E. coli, coliforms, and other enterobacteria was achieved with the glass tubes coated with the laboratory–prepared TiO₂ sol. Interestingly, this material presented superior antimicrobial performance as coating (100% of E. coli elimination) compared to its powder form. The titania coating also showed the best efficiency in the degradation of methylene blue (i.e., 95.2%), though this material lost 30% of its photoactivity after four reaction cycles.