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Strong Metal‐Support Interaction (SMSI) is a key concept in heterogeneous catalysis, but it remains underexplored in the context of photon‐to‐hydrogen conversion, as coupling of metallic nanoparticles with photocatalysts is overlooked and only discussed in terms of Schottky barrier formation. In this study, we provide deep insights into the effect of Au encapsulation with TiO2 overlayer on enhancing photocatalytic hydrogen generation. Our findings reveal that the construction of a SMSI‐like nanostructure induces the formation of oxygen vacancies at the Au‒TiO2 interface which actively facilitate charge carrier separation through interfacial band reconstruction. The presence of defects is evidenced by Electron Paramagnetic Resonance and X‐ray Photoelectron Spectroscopy, unveiling their relationship with photocatalytic activities. Consistent with experimental results, Density Functional Theory (DFT) calculations demonstrate that Au promotes oxygen vacancy formation. These vacancies located at the TiO2 surface significantly enhances H2O and MeOH adsorption during H2 evolution reactions. The SMSI‐like concept was extended to Pt, Pd, and Ag, in which the oxygen vacancy formation energy at the metal‐semiconductor interface varied depending on the metal, as computed by DFT. The results suggest that photocatalytic activity is related to the ease of oxygen vacancy formation, which is influenced by the nature of the metals. In this work, the oxygen vacancy formation is reported at the Au‐TiO2 interface in strong metal‐support interaction (SMSI) photocatalyst. The oxygen vacancies faciliate electron transfer and favor the adsorption of water and methanol at photocatalyst surface, thus enhancing the kinetic of photocatalytic hydrogen generation. The SMSI concept is extended to Pt, Pd, and Ag, in which the formation energy of oxygen vacancies at the metal‐semiconductor interface varied depending on the metal. The results indicate that the ease and the localization of oxygen vacancy formation is a critical factor governing photocatalytic acitivity.

The development of electrocatalysts with optimized intermediate adsorption and low energy barriers is crucial for the oxygen evolution reaction (OER). In this work, the d‐band center position of high‐entropy layered double hydroxides (HE‐LDHs) is modulated by substituting Mg2⁺ sites with Fe2+, Cu2+, Co2+, and Ni2+. It is demonstrated that the d‐band center position relative to the Fermi level is modified, reaching an optimal energy in (FeCuCoNi)6Al2‐LDH. The nature of the incorporated transition metals significantly influenced OH− adsorption kinetics and reduced the overpotential for OER by 55%, compared to native LDH. The stepwise substitution of Mg2⁺ by Fe2⁺ particularly induces charge carrier transfer, switching into Faradaic processes favorable to the enhancement of OER kinetics. This work provides an effective approach that allows decreasing the OER overpotential through adjusting the position of the d‐band center, and suggests that d‐band tuning via multication insertion can directly shift the material toward an optimal binding strength region, which underlies the observed performance. The d‐band center position of layered double hydroxide is adjusted via multication insertion in the octahedral site. The optimal position of the d‐band, near the Fermi level, enhances OER performance through optimal OH− adsorption kinetics, resulting in a 55% reduction in overpotential compared to the native catalyst.

Cu–TiO2 nanoparticles of a broad range of compositions with 0, 0.002, 0.005, 0.02, 0.05, 0.2, 0.5, 1.0, 2.0, 3.0, 5.0, 7.0 and 10.0 mol% Cu were synthesized via the sol–gel method using copper (II) acetate and titanium tetraisopropoxide (TTIP) precursors at a low hydrolysis ratio of H = 1.25, which favours homogeneous TiO2 nucleation and Cu dispersion in the host matrix at nanoscale. The precipitated materials were dried at 80 °C and calcined at 450, 500, and 550 °C to form crystalline nanopowders, whose photocatalytic activity was evaluated on the decomposition of a representative pollutant, methylene blue (MB), in aqueous solutions under UVA and sunlight illuminations. The compositions with small Cu content of ~0.05 mol% showed the highest activity. A gain of activity over pure titania of 4 times after calcination at 450 °C, 2.5 times at 500 °C and 20% at 550 °C was measured under UVA illumination. Even higher gain of activity observed under sunlight illumination might be due to an extension of action spectrum to the visible range due to intra-gap defect states produced by Cu2+ insertion. The time-resolved microwave conductivity (TRMC) measurements of the photoinduced charges relaxation suggest that both excessive calcination temperature and Cu content decrease the activity due to Cu-defects clustering. Modelling relates the activity to the photoinduced electron-hole pair separation; the optimal Cu content is explained by accessibility of the recombination centre by a conduction band (CB) electron. Accordingly, an increase in calcination temperature resulted in a longer pathlength of CB electron.

Metal halide perovskites (MHPs, CsPbX3: X = Cl, Br, I) have advanced the field of optoelectronic devices due to their remarkable light‐emitting capabilities, stemming from the large overlap between their emission and absorption spectra, offering the possibility to reabsorb their own emitted photons. Herein, a straightforward method is reported to confine CsPbBr3 into mesoporous silica films with a chiral nematic structure, allowing the amplification of the photoluminescence (PL). The simple room temperature ligand‐free synthesis allows facile growth of CsPbBr3 in silica photonic films, in which the Bragg peak position can be tuned from the UV to the visible range. The perovskite/silica films demonstrate a remarkable improvement in PL intensity and lifetime compared to the as‐synthesized non‐confined perovskite nanocrystals (NCs) due to the overlap of the Bragg peak position of the chiral nematic photonic films and CsPbBr3 absorption band. Such a PL enhancement stems from the slow photon effect induced at blue and red Bragg peak edges that facilitates the photon recycling of the emitted photons. This innovative approach offers a new way to fabricate highly emissive and long‐lived photoluminescent films at ambient conditions, potentially advancing perovskite utilization in light‐emitting devices. A simple ambient ligand‐free synthesis of the highly luminescent spherical CsPbBr3 perovskite nanoparticles is achieved in mesoporous silica photonic films. Such photoluminescence enhancement stems from the overlap of the Bragg peak position of the photonic films and CsPbBr3 absorption band, inducing the slow photon effect at Bragg peak edges facilitating the photon recycling of the emitted photons.

A simple precipitation-reduction method was used to prepare cubic and polyhedral Cu2O structures. Their morphological, structural, optical and electronic properties were analyzed and compared with those of commercial Cu2O by means of SEM, TEM, XRD, UV–vis DRS, Photoluminescence Spectroscopy and Time Resolved Microwave Conductivity. Methyl orange (MO) photodegradation with visible light (blue-light LEDs, λ  =  450–470  nm) was taken as a model reaction to study the photocatalytic activity. According to the results, Cu2O edge-and corner-truncated polyhedral particles significantly decreased the MO initial concentration by adsorption and photocatalysis, whereas, Cu2O cubic particles did not show MO adsorption but slightly higher photocatalytic activity than the polyhedral particles. Commercial Cu2O showed MO adsorption and high electron mobility but it was completely inactive. These results were explained in terms of the crystalline defects that influence both, the adsorption capacity and the photocatalytic activity.

Titanium dioxide (TiO2), a widely used semiconductor in photocatalysis owing to its adequate potential for water hydrolysis, chemical stability, low toxicity, and low cost. However, its efficiency is limited by fast charge-carrier recombination and poor visible light absorption. Coupling TiO2 with a p-type semiconductor, such as nickel oxide (NiO), forming a p-n heterojunction, decreases the recombination of charge carriers and increases photocatalytic activity. In this work, the surface of TiO2 modified with NiO nanoparticles (NPs) induced by radiolysis for photocatalytic hydrogen production was studied. The photocatalytic activity of NiO/TiO2 was evaluated using methanol as a hole scavenger under UV–visible light. All modified samples presented superior photocatalytic activity compared to bare TiO2. The dynamics of the charge carriers, a key electronic phenomenon in photocatalysis, was investigated by time-resolved microwave conductivity (TRMC). The results highlight the crucial role of Ni-based NPs modification in enhancing the separation of the charge carrier and activity under UV–visible irradiation. Furthermore, the results revealed that under visible irradiation, NiO-NPs inject electrons into the conduction band of titanium dioxide.

Although titanium dioxide (TiO2) has a wide range of potential applications, the photocatalytic performance of TiO2 is limited by both its limited photoresponse range and fast recombination of the photogenerated charge carriers. In this work, the preparation of nitrogen (N)-doped TiO2 accompanied by the introduction of oxygen vacancy (Vo) has been achieved via a facile annealing treatment with urea as the N source. During the annealing treatment, the presence of urea not only realizes the N-doping of TiO2 but also creates Vo in N-doped TiO2 (N-TiO2), which is also suitable for commercial TiO2 (P25). Unexpectedly, the annealing treatment-induced decrease in the specific surface area of N-TiO2 is inhibited by the N-doping and, thus, more active sites are maintained. Therefore, both the N-doping and formation of Vo as well as the increased active sites contribute to the excellent photocatalytic performance of N-TiO2 under visible light irradiation. Our work offers a facile strategy for the preparation of N-TiO2 with Vo via the annealing treatment with urea.

A mixed metal oxide W-TiO2 nanopowder photocatalyst was prepared by using the sol–gel method with a broad range of elemental compositions x = CW/(CW + CTi), including TiO2 and WO3. The material was structurally characterized and evaluated in adsorption and photocatalytic processes by testing its removal capacity of a representative pollutant methylene blue (MB) in aqueous solutions and under UV-A and sunlight illuminations. The nanopowders appeared to be more effective adsorbents than pure TiO2 and WO3 materials, showing a maximum at 15 mol% W, which was set as the tungsten solubility limit in anatase titania. At the same time, the photocatalytic decomposition of MB peaked at 2 mol% W. The examination of different compositions showed that the most effective MB removal took place at 15 mol% W, which was attributed to the combined action of adsorption and heterogeneous photocatalysis. Moreover, MB decomposition under sunlight was stronger than under UV-A, suggesting photocatalyst activation by visible light. The pollutant removal efficiency of the material with 15 mol% W was enhanced by a factor of ~10 compared to pure TiO2 at the beginning of the process, which shows its high potential for use in depollution processes in emergency cases of a great pollutant leak. As a result, a Wx=0.15-TiO2 catalyst could be of high interest for wastewater purification in industrial plants.

XRD, ESR, TRMC and UV–visible spectroscopy are used for the description of characteristics of investigated systems and determination of forming structure mechanism in Al, Zr or Ce doped non-stoichiometric ZnO1−x. It was shown the Al and Zr ions substitute the lattice Zn2+ in the ZnO matrix, and as a result, the donor's levels form in ZnO bandgap and acceptor’s level of zinc vacancy. Last level is a trap of phogenerate holes in material and it allows to delay photocatalytic actvity Al- and Zr-doped ZnO. Ce ions incorporate as interstiallite ions or segregate on crystal surface that leads to appearance the f-levels in the bandgap of ZnO, and as a result, the cerium ion will trap for electron. It decreases electron lifetime or increases of hole lifetime and also if cerium ion segregates on the ZnO surface the set of reactions (Ce4+ + e- = Ce3+, Ce3+ + O2 = Ce4+ + O2−) may occur. It leads to form additional reactive oxygen species, in particular, super-anion radicals (O2−, ROS) that improve the activity of the material. As a result, the increasing of phenol degradation by 30% compared to pure ZnO may be achieved at the choice of Ce-doped ZnO catalyst.

The electronic structure of N-TiO2 samples prepared by a sol-gel method was investigated by EPR (Electronic Paramagnetic Resonance) measurements and the energy-resolved distribution of electron traps. In EPR spectra, some of the resonance lines assigned to paramagnetic species of nitrogen and Ti3+ were detected. Sample prepared at 300 °C revealed the highest intensity line of the nitrogen paramagnetic centers, whereas that prepared at 400 °C showed a paramagnetic line for Ti3+. Measurements of the electron trap distribution showed higher density of electron traps for sample prepared at 400 °C than that at 300 °C. Sample prepared at 300 °C, which revealed the highest amount of nitrogen built in the titania in the interstitial position was the most active under visible light. It was evidenced that photocatalytic decomposition of acetaldehyde was dependent strongly on the BET surface area and electrokinetic potential of the photocatalyst surface. The UV content in the fluorescent lamp affected the yield of acetaldehyde decomposition.