Photocatalytic CO2 reduction represents a promising strategy for solar-to-fuel conversion, yet its mechanistic validity and visible-light performance remain widely debated. Niobium pentoxide (Nb2O5) has emerged as a distinctive oxide platform for CO2 reduction owing to its delocalized 4d-derived conduction band, tunable Nb4+–Vo defect states, and band-edge positions compatible with multi-electron CO2 reduction and oxidative half-reactions. Unlike previous reviews that primarily focus on material modifications, this work provides a comprehensive outline of Nb2O5-based photocatalytic systems adopted for CO2 reduction. The review was introduced by a concise discussion of Nb2O5 core merits as a potent catalyst for CO2 reduction. Then, the CO2 reduction process was discussed from thermodynamic, kinetic, and mechanistic perspectives. Afterwards, we critically analyzed how morphology and bandgap engineering, controlled defect engineering, heterojunction formation, and cocatalyst integration can modulate charge-carrier dynamics, CO2 adsorption, intermediate stabilization, and product selectivity. In addition, a theoretical insight based on density functional theory (DFT) calculations was conveyed to unravel the structure-activity interplay and reaction mechanism of CO2 conversion over Nb2O5-based photocatalytic systems. Finally, current limitations and outlooks are provided to motivate future studies on developing Nb2O5-based photocatalysts with adequate reactivity, selectivity, and stability.

This study explores the photocatalytic performance of ZnO nanosponge (ZnO NSp), g‐C 3 N 4 nanosheet (g‐C 3 N 4 NSh), and their composite in degrading methylene blue (MB) under UV and visible‐light irradiation. ZnO NSp displayed superior activity under UV light, achieving > 99% MB removal within 30 min and exhibiting the highest pseudo‐first‐order rate constant (0.124 min −1 ), outperforming both g‐C 3 N 4 NSh and the composite. In contrast, under visible light, the g‐C 3 N 4 NSh/ZnO NSp composite achieved 98% degradation within 60 min, attributed to enhanced charge separation across the heterojunction interface. The photocatalytic efficiency was influenced by pH, with neutral to alkaline conditions favoring MB removal through improved catalyst stability and adsorption capacity. Radical scavenging experiments confirmed superoxide (O 2 • − ) and hydroxyl (HO•) radicals as the dominant reactive species driving degradation. These results demonstrate the complementary advantages of ZnO NSp and g‐C 3 N 4 NSh in different irradiation regimes and highlight the promise of their composite as an efficient, solar‐responsive photocatalyst for wastewater remediation.

"Blue titania" is widely applied in photocatalysis, but comparative studies on the influence of the TiO2 phase on color evolution and stability are rare. Here, this knowledge gap is closed by evaluating comparatively the formation of blue titania from pure anatase, pure rutile, P25 (similar to 80% anatase, 20% rutile), and partially amorphous materials. The blue color is attained by photocatalytic reaction of 2-propanol on TiO2 under oxygen-free conditions. It is additionally evaluated how different irradiation conditions and the intentional presence of oxygen influence TiO2 coloration. A high surface area is found to lead to rapid discoloration. Rutile is more stable against discoloration in air than an anatase of similar particle size. The mixed-phase material P25 shows exceptional behavior: It reaches the strongest blue color and retains the color the longest time under ambient conditions. In the presence of oxygen, photooxidation of 2-propanol still causes a blue color of TiO2, which is explained by a slow transfer of photogenerated electrons over the interface. Insights gained with standard materials is complemented by experiments with an engineered aerogel material previously shown to be remarkably active in the storage of charge carriers. The influence of restricted oxygen diffusion in pressed aerogel pellets is also discussed.

Zinc oxide nanoparticles (ZnO NPs) were synthesized using a simple and eco-friendly precipitation method, employing a capping agent derived from chia seeds (Salvia hispanica). X-ray diffraction (XRD) analysis confirmed the formation of ZnO with a hexagonal crystal structure and an average crystallite size of less than 30 nm. Scanning electron microscopy (SEM) revealed distinct quasi-spherical and nanorod-like morphologies, while energy-dispersive X-ray spectroscopy (EDX) verified the presence of zinc and oxygen. Diffuse reflectance spectroscopy (DRS) indicated significant activity in the UV region, with the nanoparticles exhibiting a band gap of 3.25 eV. The photocatalytic efficiency of the synthesized ZnO NPs was evaluated through their ability to degrade diclofenac sodium (DCF) and para-nitrophenol (4-nitrophenol, PNP) under UV-LED irradiation, achieving pollutant removal rates exceeding 98%. The degradation mechanism is clarified by a detailed characterization of the reaction intermediates. These findings highlight the potential of ZnO NPs synthesized from chia seed extract for effective environmental remediation of pharmaceutical and organic pollutants.

The palladium-catalyzed Suzuki-Miyaura cross coupling reaction to forge carbon-carbon bonds fundamentally changes the practice of organic synthesis. Herein an isolated palladium catalyst supported on polymeric carbon nitride (Pd/PCN) for efficient cross coupling of bromobenzene and phenylboronic acid at room temperature is reported. It is demonstrated that the Pd/PCN catalyst with a 2 wt% Pd loading achieves the highest mole-specific activity. In addition, the size of supported Pd can strongly affect the reaction performance: the isolated Pd species exhibit higher activity compared to the Pd nanoparticles. The continuous flow tests demonstrate that the catalytic properties of the Pd/PCN catalyst strongly depend on the reaction atmosphere: Pd-catalyzed self-coupling of phenylboronic acid as a side reaction is more pronounced under an O2 flow than in an Ar flow. Detailed mechanistic investigations through in situ infrared spectroscopy reveal the role of the base K2CO3 in activating the phenylboronic acid.

The title compound, C9H8BrClO, crystallizes in the monoclinic space group P21/n with four molecules in the unit cell. The molecular structure consists of almost planar molecules with the chlorine atom protruding from this plane.

The title compound, C9H8BrClO, crystallizes in the monoclinic space group P21/n with four mol-ecules in the unit cell. The mol-ecular structure consists of almost planar mol-ecules with the chlorine atom protruding from this plane.

The title compound, 3-chloro-propio-phenone (or 3-chloro-1-phenyl-propan-1-one), C9H9ClO, consists of an almost planar mol-ecule that is charaterized by very small torsion angles within the alkyl side chain (torsion angles < 6.3°). No hydrogen bonds are observed in the crystal packing. The compound exhibits a melting point of 54°C.

The title compound, 3-chloro­propio­phenone C9H9ClO, consists of an almost planar mol­ecule that is charaterized by very small torsion angles within the alkyl side chain (torsion angles < 6.3°).

A comprehensive and reliable view on the influence of UV light and heat on optical properties of ZnO shall be outlined mainly based on research conducted by scientists from Warsaw Pact countries throughout the 20th century. The problems of language barrier and loss of knowledge are being addressed. An insight into processes of photodesorption and photoadsorption of oxygen and other gas phase molecules leading to changes in charge carrier states is outlined. While desorption of surface adsorbates leads to increased number of conduction electrons and thus increased absorbance of infrared light, adsorption of electronegative gas phase molecules leads to quenching in fluorescence.

This work addresses the often-overlooked effect of light-induced sorption behavior of CO2 on powder TiO2 surfaces, as potential first step to photocatalytic CO2 activation. These investigations will lead to a more detailed understanding of the light-induced chemistry of CO2 on TiO2, to eventually unravel the CO2 photoreduction mechanism.

The title compound, 3-chloropropiophenone (or 3-chloro-1-phenylpropan-1-one), C9H9ClO, consists of an almost planar molecule that is charaterized by very small torsion angles within the alkyl side chain (torsion angles < 6.3°). No hydrogen bonds are observed in the crystal packing. The compound exhibits a melting point of 54°C.

A urea-based pristine polymeric carbon nitride catalyzes the aerobic epoxidation of citronellol under visible light irradiation with low-power blue LEDs. Formation of 6,7-epoxycitronellol in this reaction is remarkably selective yet relatively slow requiring 72 h of continuous irradiation. The aerobic photocatalyzed epoxidation is readily accelerated with isobutyraldehyde as a comediator, and a general photocatalytic procedure for the epoxidation of terpenoid substrates as well as styrene derivatives is thus developed to give the corresponding epoxides in good yields within attractive reaction times. The carbon nitride-photocatalyzed aerobic epoxidation is demonstrated in 14 examples, and the epoxidation of citronellol enables a short and sustainable three-step synthesis of the industrially relevant terpenoid fragrance compound rose oxide.

The title compound consists of almost planar mol­ecules with the chlorine atom protruding from this plane.

A set of five polymeric carbon nitrides (pCNs) made from diverse low-molecular precursors was compared with metal chalcogenide and pnictogenide semiconductors for their effectiveness in visible light-induced organic radical reactions. The productivity of the heterogenous photocatalysts in the decarboxylative Giese addition of N-phenylglycine with cyclopentenone was studied at different irradiation wavelengths ranging from 380 to 450 nm, as well as in the deaminative radical donor-acceptor-donor (DAD) three-component coupling of N-benzyl pyridinium salts with N-methylmaleimide and 1,1-diarylethylenes. The heterogenous photocatalytic radical three-component reactions were achieved in high diastereoselectivities and with high yields if the electronic and steric properties of the reactants were matched with the appropriate heterogeneous photocatalyst.

Exfoliation into a 2D nanosheet structure can lead to enhanced surface activity and unique optical and electronic properties in polymeric carbon nitride (PCN). In this study, four common exfoliation strategies (liquid ultrasonication, thermal oxidation, hydrothermal oxidation, and chemical oxidation) were adopted, and their effects on the structural and electronic changes in PCN were analyzed in detail. This allows us to understand the relationship between the exfoliation mechanism and the structural/optical properties. Here, we demonstrate that the thermal and ultrasonic exfoliation methods can effectively reduce the thickness of PCN while preserving its original structure. In contrast, the chemical and hydrothermal treatments can strongly affect the morphology and structure of PCN, leading to a decreased performance in phenol photodegradation. Therefore, depending on the employed exfoliation method, the surface area, functionalization, band edge positions, charge carrier generation, and mobility are influenced differently up to the point where semiconducting behavior is entirely lost. Our results allow conclusions about the applicability of the different exfoliation methods to obtain distinct material properties for photocatalytic applications.

Herein, the successful construction of heterostructure Cs3Bi2Br9/H2Ti3O7 (CBB/HTiO-NT) consisting of nanoparticles of lead-free halide perovskite Cs3Bi2Br9 (CBB) on hydrogen titanate nanotubes (H2Ti3O7, HTiO-NT) is reported. The application of this heterostructure was intensively investigated in the photocatalytically induced selective oxidation of hydroxymethylfurfural (HMF) to 2,5-furandicarboxaldehyde (FDC) and of benzyl alcohol (BnOH) to benzoic acid (BzA). The weight % (wt %) of CBB nanoparticles was optimized, and the resulting optimal CBB/HTiO-NT heterostructure was deeply analyzed. Comprehensive analysis of the morphology and structure demonstrated the successful combination of HTiO-NT and CBB in CBB/HTiO-NT heterostructures. If the CBB content is too low, it is not stable, potentially because it decomposes at the interface with HTiO-NT. The 30 wt % CBB/HTiO-NT heterojunction exhibited the most efficient photooxidation of HMF and BnOH, with selectivity of 87% for FDC and 81% for BzA, respectively, in an organic solution irradiated by blue light. Analysis of optical and photoelectrochemical properties revealed that the inclusion of CBB nanoparticles into HTiO-NT led to enhanced mobility of charge carriers and improved photocatalytic efficiency. The oxidative characteristics and rate of charge carrier migration in the CBB/HTiO-NT heterostructure were enhanced by the geometry and tubular structure of HTiO-NT, thereby promoting the formation of superoxide (O-2(-)) radicals. Furthermore, scavenger experiments have demonstrated the essential role of the photogenerated species, specifically h(+), e(-), and O-2(-), in the process of HMF photooxidation. Consequently, a plausible chemical pathway for the photocatalytic oxidation of HMF to FDC was presented. However, additional improvement of the stability of the composite material is necessary. The present study offers a potential approach to improve photocatalytic conversions to value-added chemicals by utilizing CBB/HTiO-NT-based photocatalysts.

The development of highly efficient and stable visible-light-driven photocatalysts for the removal of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) from water is still a challenge. In this work, Bi2MoO6 (BMO) materials with different morphology were successfully prepared via a simple hydrothermal method by altering the solvent. The morphology of the BMO material is mainly influenced by the solvent used in the synthesis (H2O, ethanol, and ethylene glycol or their mixtures) and to a lesser extent by subsequent thermal annealing. BMO with aggregated spheres and nanoplate-like structures hydrothermally synthesized in ethylene glycol (EG) and subsequently calcined at 400 °C (BMO-400 (EG)) showed the highest adsorption capacity and photocatalytic activity compared to other synthesized morphologies. Complete degradation of 2,4-D on BMO upon irradiation with a blue light-emitting diode (LED, λmax = 467 nm) was reached within 150 min, resulting in 2,4-dichlorophenol (2,4-DCP) as the main degradation product. Holes (h+) and superoxide radicals (⋅O2−) are assumed to be the reactive species observed for the rapid conversion of 2,4-D to 2,4-DCP. The addition of H2O2 to the reaction mixture not only accelerates the degradation of 2,4-DCP but also significantly reduces the total organic carbon (TOC) content, indicating that hydroxyl radicals are crucial for the rapid mineralization of 2,4-D. Under optimal conditions, the TOC value was reduced by 84.5% within 180 min using BMO-400 (EG) and H2O2. The improved degradation performance of BMO-400 (EG) can be attributed to its particular morphology leading to lower charge transfer resistance, higher electron–hole separation, and larger specific surface area.

The nature of the support can fundamentally affect the function of a heterogeneous catalyst. For the novel type of isolated metal atom catalysts, sometimes referred to as single-atom catalysts, systematic correlations are still rare. Here, we report a general finding that Pd on nitride supports (non-metal and metal nitride) features a higher oxidation state compared to that on oxide supports (non-metal and metal oxide). Through thorough oxidation state investigations by X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), CO-DRIFTS, and density functional theory (DFT) coupled with Bader charge analysis, it is found that Pd atoms prefer to interact with surface hydroxyl group to form a Pd(OH) x species on oxide supports, while on nitride supports, Pd atoms incorporate into the surface structure in the form of Pd−N bonds. Moreover, a correlation was built between the formal oxidation state and computational Bader charge, based on the periodic trend in electronegativity.

The accumulation of active pharmaceutical ingredients in the aqueous environment is a serious problem that will become even more concerning in the future. In this work, the photocatalytic degradation of ciprofloxacin (CIP) in aqueous solution was assessed over P25-TiO2 coated open microchannels with gravity-driven flow under UV-A irradiation. The deposition of different amounts of TiO2 in the microchannels was carried out via a facile, selfdeveloped procedure. The degradation kinetics of ciprofloxacin was described via the Langmuir-Hinshelwood mechanism. Since the flow characteristics in the microchannel had influence on the concentration distribution of CIP in the microchannel, the coupled momentum and mass conservation law was solved numerically in MATLAB 2023a (2D case) as well as in ANYS Fluent 2023 R1 (2D and 3D cases). Although the implemented 2D model in MATLAB 2023a allowed the preliminary estimation of the selected kinetic parameters, namely adsorption equilibrium constant and specific Langmuir-Hinshelwood rate constant, the sensitivity of the model was not satisfactory which was attributed to the empirical correlations used for the estimation of the external mass transfer coefficient. The 2D and 3D models in ANSYS Fluent 2023 R1 predicted efficiently the outlet concentration of ciprofloxacin for different inlet CIP concentrations and liquid phase flow rates. Therefore, the as developed 2D and 3D models in ANSYS Fluent 2023 R1 can be used for the design of reactors containing coated microchannels with gravity-driven flow for photocatalytic degradation of active pharmaceutical ingredients.