This work presents a comparative study of the efficiency of two commercial TiO₂ photocatalysts, Aeroxide P25 (ATiO₂) and Sachtleben Hombikat UV100 (HTiO₂), in H₂ production from an aqueous solution of naphthalene. The TiO₂ photocatalysts were platinized by the photodeposition method varying the platinum content of the suspension to 0.5, 1.0, and 5.0 wt%. A full physicochemical characterization for these materials was performed, showing no structural effects from the deposition method, and confirming a well dispersion of nanosized-Pt⁰ particles on the surface of both photocatalysts. Pristine ATiO₂ shows around 14% higher photocatalytic fractional conversion of naphthalene than pristine HTiO₂ after 240 min of irradiation, while both materials exhibit negligible activity for H₂ formation. The 0.5 wt% Pt- HTiO₂ increases the photocatalytic fractional conversion of naphthalene from 71% to 82% and produces 6 µmol of H₂. However, using a higher Pt content than the optimal platinization ratio of 0.5 wt% dramatically inhibits both processes. On the other hand, regardless of the fractional ratio of Pt, the platinization of ATiO₂ results in a decrease in the fractional conversion of naphthalene by 4% to 33% of the pristine value. Although the presence of Pt islands on the surface of the ATiO₂ is essential for the H₂ evolution, no dependency between the Pt ratio and the H₂ formation rate was observed since all the platinized materials show a similar H₂ formation of around 3 µmol. Based on the EPR results, the higher photocatalytic activity of the Pt-HTiO₂ is attributed to the efficient charge carrier separation and its larger surface area. The recyclability test confirms that the inhibition of the photocatalytic process is related to the deactivation of the photocatalyst surface by the adsorption of the photoformed intermediates. A strong relationship between the photocatalytic activity and the kind of the aromatic compounds was observed. The H₂ evolution and the photooxidation of the aromatic hydrocarbons exhibit higher photonic efficiencies than that of their corresponding hydroxylated compounds over the Pt-HTiO₂. Full article

A series of eleven push–pull chromophores with specific structures have been designed for the free radical polymerization of acrylates, but also for the fabrication of photocomposites and 3D-printed structures. New photoinitiating systems comprising the different push–pull dyes showed excellent photochemical reactivities at 405 nm. Notably, polymerization reactions could be initiated with light-emitting diodes (LEDs) which constitute a unique opportunity to promote the free radical polymerization under mild conditions, i.e., low light intensity (e.g., sunlight) and under air. Photopolymerization is an active research field, and push–pull dyes have already been investigated for this purpose. Besides, it remains of crucial interest to investigate new reactive structures capable of efficiently initiating photopolymerization reactions. The plausible potential of these structures to act as efficient photoinitiators in vat photopolymerization (or 3D printing) and fabrication of photocomposites prompts us to select eleven new push–pull dyes to design multi-component photoinitiating systems activable with LEDs emitting at 405 nm. Precisely, a tertiary amine, i.e., ethyl dimethylaminobenzoate (EDB) used as an electron/hydrogen donor and an iodonium salt used as an electron acceptor were selected to behave as powerful co-initiators to construct three-component photoinitiating systems (PISs) with the different push–pull dyes. Among these new PISs, dye 8 and 9-based PISs could efficiently promote the free radical photopolymerization of acrylates upon exposure to a LED emitting at 405 nm also upon sunlight irradiation, highlighting their huge performance. Photoinitiating abilities could be explained on the basis of steady state photolysis experiments. Fluorescence measurements and electron spin resonance (ESR) spin-trapping experiments were also performed to obtain a deeper insight into the chemical mechanisms supporting the polymerization reaction and determine the way the initiating species, i.e., the radicals, are observed. Finally, two investigated dye-based PISs were applied to the fabrications of photocomposites. Three-dimensional patterns with excellent spatial resolutions were generated by the laser writing technique to identify the effects of photopolymerization of acrylates both in the absence and presence of fillers (silica). Interestingly, comparison between the 3D objects fabricated by the PISs/monomer systems and the PISs/monomer/filler photocomposites indicates that the newly designed photocomposites are suitable for practical applications. Full article

In asymmetric photocatalytic reactions, it is necessary to study the mechanism of the asymmetric electromagnetic interaction between molecules and light. In this work, we theoretically studied the electromagnetic interactions between the light-induced charge transfer reaction and the chiral reaction of PM567 dye. We found that the chiral responses of molecules in different wavelength ranges were partially due to pyrromethene and binaphthalene. Therefore, the catalytic sites with different chirality also corresponds to the two-part groups. Through quantitative analysis, we found the entire analysis process to be complete and self-consistent. Full article

Developing simple and effective synthetic strategies regarding the formation of heterostructure photocatalytic semiconductors remains an intense challenge in research matters. Uniform heterostructure cobalt oxide@meso–CN@MoS₂ (CoO@meso–CN@MoS₂) photocatalyst exhibits excellent photocatalytic redox performance for pollutant degradation under visible light. By adjusting the weight ratio of CoO@meso–CN and MoS₂, we fabricated a CoO@meso–CN@MoS₂ heterostructure photocatalyst, and the established heterostructure between CoO@meso–CN and MoS₂ was indicated by various physicochemical and morphological characterizations. The photocatalytic response to the fabricated hybrid was determined by rodamine B (RhB), methylene blue (MB), and congo red (CR) degradation in aqueous solution under visible light, and the nanocomposites with a slight content consisting of CoO@meso–CN achieved better catalysis than pure MoS₂. This finding confirmed the propriety of this heterostructure as a valuable photocatalyst. The experimental results demonstrated that the apparent reaction rate constant of the 3 wt% CoO@meso–CN modified MoS₂ was about two times higher than that of pure MoS₂. The present work serves as a new approach for designing highly efficient visible light-induced heterostructure-based photocatalysts for environmental applications in the future. Full article

Black TiO₂ with doped nitrogen and modified carbon (b-N-TiO₂/C) were successfully prepared by sol-gel method in the presence of urea as a source of nitrogen and carbon. The photocatalysts were characterized by field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, electron paramagnetic resonance (EPR), and UV-vis diffuse reflectance spectra (DRS). The doped nitrogen, introduced defects, and modified carbon played a synergistic role in enhancing photocatalytic activity of b-N-TiO₂/C for the degradation of chlorophyll-a in algae cells. The sample, with a proper amount of phase composition and oxygen vacancies, showed the highest efficiency to degrade chlorophyll-a, and the addition of H₂O₂ promoted this photocatalysis degradation. Based on the trapping experiments and electron spin resonance (ESR) signals, a photocatalytic mechanism of b-N-TiO₂/C was proposed. In the photocatalytic degradation of chlorophyll-a, the major reactive species were identified as OH and O₂⁻. This research may provide new insights into the photocatalytic inactivation of algae cells by composite photocatalysts. Full article

Pt nanowire-anchored dodecahedral Ag₃PO₄{110} was constructed for organics photodegradation. SEM and TEM images confirmed that the Pt nanowires were grafted on dodecahedral Ag₃PO₄, which was entirely bounded by {110} facets. All the X-ray diffraction peaks of the samples were indexed to the body-centered cubic phase of Ag₃PO₄, indicating that Pt nanowire-anchored dodecahedral Ag₃PO₄ well maintained the original crystal structure. The rhombic dodecahedral Ag₃PO₄ entirely bounded by {110} facets achieved high photocatalytic activity. Due to the formation of a Schottky barrier, the Pt nanowires improved the separation of the charge carriers of Ag₃PO₄. Furthermore, they provided a fast expressway to transfer the photogenerated electrons and prolonged the lifetime of the charge carriers via long-distance transport, resulting in the accumulation of holes on Ag₃PO₄ for organics degradation. More importantly, the Pt nanowires improved the reduction potential of the photogenerated electrons for O₂ reduction to ·O₂⁻, which enhanced the photocatalytic activity and anti-photocorrosion properties of Ag₃PO₄. We found that 99.5% of Rhodamine B (RhB) could be removed over 0.5ωt% Pt nanowire-anchored dodecahedral Ag₃PO₄ within 10 min. Even after 10 cycles, the photocatalytic activity was still high. photoluminescence (PL), time-resolved photoluminescence (TRPL), UV–vis diffuse reflectance spectra (UV–visDRS), and photoelectrochemical analysis showed that Pt nanowire-anchored dodecahedral Ag₃PO₄ exhibited lower bandgap, higher photocurrent intensity, better electronic conductivity, and longer charge carriers lifetime than other types of Ag₃PO₄ crystals. Radical trapping experiments and electron paramagnetic resonance (EPR) analysis demonstrated that the holes were the main active species for organics photodegradation. Full article

Recent years have witnessed an incredibly high interest in perovskite-based materials. Among this class, metal halide perovskites (MHPs) have attracted a lot of attention due to their easy preparation and excellent opto-electronic properties, showing a remarkably fast development in a few decades, particularly in solar light-driven applications. The high extinction coefficients, the optimal band gaps, the high photoluminescence quantum yields and the long electron–hole diffusion lengths make MHPs promising candidates in several technologies. Currently, the researchers have been focusing their attention on MHPs-based solar cells, light-emitting diodes, photodetectors, lasers, X-ray detectors and luminescent solar concentrators. In our review, we firstly present a brief introduction on the recent discoveries and on the remarkable properties of metal halide perovskites, followed by a summary of some of their more traditional and representative applications. In particular, the core of this work was to examine the recent progresses of MHPs-based materials in photocatalytic applications. We summarize some recent developments of hybrid organic–inorganic and all-inorganic MHPs, recently used as photocatalysts for hydrogen evolution, carbon dioxide reduction, organic contaminant degradation and organic synthesis. Finally, the main limitations and the future potential of this new generation of materials have been discussed. Full article

Hydrogen is considered to be an ideal energy carrier to achieve low-carbon economy and sustainable energy supply. Production of hydrogen by catalytic reforming of organic compounds is one of the most important commercial processes. With the rapid development of photocatalysis in recent years, the applications of photocatalysis have been extended to the area of reforming hydrogen evolution. This research area has attracted extensive attention and exhibited potential for wide application in practice. Photocatalytic reforming for hydrogen evolution is a sustainable process to convert the solar energy stored in hydrogen into chemical energy. This review comprehensively summarized the reported works in relevant areas, categorized by the reforming precursor (organic compound) such as methanol, ethanol and biomass. Mechanisms and characteristics for each category were deeply discussed. In addition, recommendations for future work were suggested. Full article