Search Results (25)

Heterogeneous photocatalysis has emerged as a versatile and sustainable technology for the degradation of emerging contaminants in water. This review highlights recent advancements in photocatalysts design, including band gap engineering, heterojunction formation, and plasmonic enhancement to enable visible-light activation. Various reactor configurations, such as slurry, immobilized, annular, flat plate, and membrane-based systems, are examined in terms of their efficiency, scalability, and operational challenges. Hybrid systems combining photocatalysis with membrane filtration, adsorption, Fenton processes, and biological treatments demonstrate improved removal efficiency and broader applicability. Energy performance metrics such as quantum yield and electrical energy per order are discussed as essential tools for evaluating system feasibility. Special attention is given to solar-driven reactors and smart responsive materials, which enhance adaptability and sustainability. Additionally, artificial intelligence and machine learning approaches are explored as accelerators for catalyst discovery and process optimization. Altogether, these advances position photocatalysis as a key component in future water treatment strategies, particularly in decentralized and low-resource contexts. The integration of material innovation, system design, and data-driven optimization underlines the potential of photocatalysis to contribute to global efforts in environmental protection and sustainable development. Full article

Pharmaceutical residues are emerging contaminants of growing concern due to their persistence and poor removal efficiency in conventional wastewater treatment plants. This study evaluates UVC photolysis with type C ultraviolet radiation (UVC) and UVC/TiO₂ photocatalysis of a mixture of four pharmaceuticals—atenolol (ATL), acetaminophen (ACM), clofibric acid (CLA), and antipyrine (ANT)—commonly found in treated urban wastewater. A comprehensive kinetic model was developed to describe their degradation, taking into account the generation of reactive oxygen species (ROS): hydroxyl (HO^●), superoxide ion (O₂^●−) radicals, and singlet oxygen (¹O₂), along with their reactions with both the pharmaceuticals and dissolved organic matter. Direct quantum yields were determined as 8.05 × 10⁻³ mol·Einstein⁻¹ for ATL, 1.93 × 10⁻³ for ACM, 3.12 × 10⁻¹ for CLA, and 5.12 × 10⁻² for ANT. In addition, rate constants of the reactions between singlet oxygen and pharmaceuticals were 9.93, 1.3 × 10⁶, 1.18 × 10², and 1.14 × 10⁴ M⁻¹s⁻¹ for ATL, ACM, CLA, and ANT, respectively. Scavenger experiments confirmed the key role of the ROS involved. The model reproduces the inhibitory effect of natural organic matter in secondary effluent and, in most cases, treated, accurately predicts the concentration profiles of the pharmaceuticals. Under photocatalytic conditions (0.10 g·L⁻¹ TiO₂), all compounds were completely degraded in less than 15 min. This validated model provides a useful tool for understanding the degradation mechanisms of pharmaceutical mixtures and for supporting the design of effective water strategies based on photochemical processes. Full article

This study investigates the synthesis and photoluminescent properties of carbon quantum dots (CQDs) derived from Actinidia deliciosa using the hydrothermal method. The effect of concentration and pH on the composition, structure, and optical properties of CQDs was analyzed using characterization techniques such as TEM, EDS, FTIR, UV-Vis, and photoluminescence (PL) spectroscopy. The CQDs exhibited particle sizes ranging from 1 to 10 nm, with a graphitic structure and oxygen-containing functional groups, as identified by FTIR bands corresponding to OH, C=O, and C=C. The stability analysis revealed particle agglomeration over 30 days, increasing the size up to <40 nm. Regarding the optical properties, the CQDs displayed absorption peaks at 225 and 280 nm and a bandgap of ~3.78–3.82 eV. The PL characterization demonstrated tunable emission from violet to green, depending on the excitation wavelength. CQDs synthesized at an acidic pH of 2 exhibited enhanced luminescence due to protonation effects, whereas an alkaline pH led to a reduction in emission intensity. The hydrothermal method enabled a simple and eco-friendly synthesis, using water as the sole solvent, yielding stable CQDs with a luminescence lifespan exceeding 30 days. Their optical and electronic properties make them promising candidates for photocatalysis, heavy metal detection, and bioimaging applications. Full article

This review focuses on the research progress related to carbon dots (CDs) derived from Chinese herbal medicines and tea, covering preparation methods, physicochemical properties, and application fields. It elaborates on preparation approaches like hydrothermal, solvothermal, microwave-assisted, and ultrasonic-assisted methods, and their influence on CDs’ structure and properties. It also explores CDs’ structural and optical properties. The application fields include antibacterial, sensing, bioimaging, photocatalysis, hemostasis, and energy. Carbon dots show antibacterial activity by destroying bacterial cell membranes, they can detect various substances in sensing, are important for bioimaging, degrade organic pollutants in photocatalysis, have hemostatic and anti-inflammatory effects, and can be used as battery anode materials. Despite progress, challenges remain in improving yield, quantum yield, property control, and understanding their mechanism of action. This review provides a reference for related research and looks ahead to future directions. Full article

Halide perovskite has shown great potential in photocatalysis owing to its diversity, suitable energy band alignment, rapid charge transfer, and excellent optical properties. However, poor stability, especially under humid conditions, hinders their practical application in photocatalysis. In this work, we report the encapsulation of inorganic–organic hybrid perovskite QDs into MIL-101(Cr) through an in situ growth strategy to prepare a series of MAPbBr₃@MIL-101(Cr) (MA = CH₃NH₃⁺) composites. The perovskite precursors, i.e., MABr and PbBr₂, were successively introduced into the pores of MOF, where the perovskite quantum dots were self-assembled in the confined environment. In photocatalytic CO₂ reduction, 11%MAPbBr₃@MIL-101(Cr) composite displayed the best performance among the composites with a total CO and CH₄ yield of 875 μmol g⁻¹ in 9 h, which was 8 times higher than that of the pure MAPbBr₃. Such high gas production efficiency could be maintained for 78 h at least without structural and morphologic decomposition. The remarkable stability and catalytic activity of composites are mainly due to the synergistic effect and improved electron transfer between MAPbBr₃ and MIL-101(Cr). Moreover, these composites revealed a novel mechanism, showing switched CH₄ selectivity with the controlling of the perovskite location and contents. Those with perovskites encapsulated in the mesopores of MIL-101(Cr) were more preferential for CO production, while those with perovskites encapsulated in both meso- and micropores could produce CH₄ dominantly. Full article

Carbon dots (CDs) have emerged as a promising class of carbon-based nanomaterials due to their unique properties and versatile applications. Carbon dots (CDs), also known as carbon quantum dots (CQDs) or graphene quantum dots (GQDs), are nanoscale carbon-based materials with dimensions typically less than 10 nanometers. They exhibit intriguing optical, electronic, and chemical properties, making them attractive for a wide range of applications, including sensing, imaging, catalysis, and energy conversion, among many others. Both bottom-up and top-down synthesis approaches are utilized for the synthesis of carbon dots, with each method impacting their physicochemical characteristics. Carbon dots can exhibit diverse structures, including amorphous, crystalline, or hybrid structures, depending on the synthesis method and precursor materials used. CDs have diverse chemical structures with modified oxygen, polymer-based, or amino groups on their surface. These structures influence their optical and electronic properties, such as their photoluminescence, bandgap, and charge carrier mobility, making them tunable for specific applications. Various characterization methods such as HRTEM, XPS, and optical analysis (PL, UV) are used to determine the structure of CDs. CDs are cutting-edge fluorescent nanomaterials with remarkable qualities such as biocompatibility, low toxicity, environmental friendliness, high water solubility, and photostability. They are easily adjustable in terms of their optical properties, making them highly versatile in various fields. CDs find applications in bio-imaging, nanomedicine, drug delivery, solar cells, photocatalysis, electrocatalysis, and other related areas. Carbon dots hold great promise in the field of solar cell technology due to their unique properties, including high photoluminescence, high carbon quantum yield (CQY), and excellent charge separation. Full article

The aqueous instability of halide perovskite seriously hinders its direct application in water as a potential photocatalyst. Here, we prepared a new type of polyvinylpyrrolidone (PVP) passivated δ-CsPbI₃ (δ-CsPbI₃@PVP) microcrystal by a facile method. This material can be uniformly dispersed in water and stably maintain its crystal structure for a long time, breaking through the bottleneck of halide perovskite photocatalysis in water. Under visible light, δ-CsPbI₃@PVP can almost completely photodegrade organic dyes (including Rhodamine B, methylene blue, and crystal violet) in only 20 min. The efficient photocatalytic activity is attributed to the enhanced visible light absorption arising from PbI₂ defects in δ-CsPbI₃@PVP and the intrinsic low photoluminescence quantum yield of δ-CsPbI₃, which induces efficient light absorption and photocatalytic activity. We highlight δ-CsPbI₃@PVP as an effective aqueous photocatalyst, and this study provides new insights into how to exploit the potential of halide perovskite in photocatalytic applications. Full article

Hydrogen-bonded organic frameworks (HOFs) are a kind of crystalline porous material that have shown great potential for photocatalysis on account of their mild synthesis conditions and high crystallinity. Perylene-based photocatalysts have great potential for photocatalytic H₂O₂ production due to their excellent photochemical stability and broad spectral absorption. In this work, we designed and synthesized a high crystalline perylene-based HOF (PTBA) and an amorphous analog sample PTPA for photocatalytic H₂O₂ evolution. Under visible light irradiation, PTBA shows a higher photocatalytic H₂O₂ production rate of 2699 μmol g⁻¹ h⁻¹ than PTPA (2176 μmol g⁻¹ h⁻¹) and an apparent quantum yield (AQY) of 2.96% at 500 nm. The enhanced photocatalytic performance of PTBA is attributed to the promotion of the separation and transfer of photocarriers due to its high crystallinity. This work provides a precedent for the application of HOFs in the field of photocatalytic H₂O₂ generation. Full article

The marine environment offers a vast array of resources, including plants, animals, and microorganisms, that can be utilized to extract polysaccharides such as alginate, carrageenan, chitin, chitosan, agarose, ulvan, porphyra, and many more. These polysaccharides found in marine environments can serve as carbon-rich precursors for synthesizing carbon quantum dots (CQDs). Marine polysaccharides have a distinct advantage over other CQD precursors because they contain multiple heteroatoms, including nitrogen (N), sulfur (S), and oxygen (O). The surface of CQDs can be naturally doped, reducing the need for excessive use of chemical reagents and promoting green methods. The present review highlights the processing methods used to synthesize CQDs from marine polysaccharide precursors. These can be classified according to their biological origin as being derived from algae, crustaceans, or fish. CQDs can be synthesized to exhibit exceptional optical properties, including high fluorescence emission, absorbance, quenching, and quantum yield. CQDs’ structural, morphological, and optical properties can be adjusted by utilizing multi-heteroatom precursors. Moreover, owing to their biocompatibility and low toxicity, CQDs obtained from marine polysaccharides have potential applications in various fields, including biomedicine (e.g., drug delivery, bioimaging, and biosensing), photocatalysis, water quality monitoring, and the food industry. Using marine polysaccharides to produce carbon quantum dots (CQDs) enables the transformation of renewable sources into a cutting-edge technological product. This review can provide fundamental insights for the development of novel nanomaterials derived from natural marine sources. Full article

The development of visible-light active titanium dioxide is one of the key challenges in photocatalysis that stimulates the development of TiO₂-based composite materials and methods for their synthesis. Here, we report the use of pristine and Pt-modified dark titanium dioxide prepared via pulsed laser ablation in liquid (Nd:YAG laser, 1064 nm, 7 ns) for photocatalytic hydrogen evolution from alcohol aqueous solutions. The structure, textural, optical, photoelectrochemical, and electrochemical properties of the materials are studied by a complex of methods including X-ray diffraction, low-temperature nitrogen adsorption, electrophoretic light scattering, diffuse reflection spectroscopy, photoelectrochemical testing, and electrochemical impedance spectroscopy. Both the thermal treatment effect and the effect of modification with platinum on photocatalytic properties of dark titania materials are studied. Optimal compositions and experimental conditions are selected, and high photocatalytic efficiency of the samples in the hydrogen evolution reaction (apparent quantum yield of H₂ up to 0.38) is demonstrated when irradiated with soft UV and blue LED, i.e., 375 and 410 nm. The positive effect of low platinum concentrations on the increase in the catalytic activity of dark titania is explained. Full article

ZnO and TiO₂ are semiconductor nanomaterials that are widely used in photocatalysis. However, the relatively high recombination rate and low quantum yield of photogenerated electron–hole pairs limit their practical applications. In this study, a series of TiO₂/ZnO/diatomite composites with various compositions were successfully prepared via a two-step precipitation method. They exhibited stronger UV–visible absorption properties and substantially lower fluorescence intensities than those of ZnO and ZnO/diatomite, which was mainly due to the low recombination rate of the photogenerated electron–hole pairs in the composite system. The reaction intermediates of methylene blue were detected by liquid chromatography–mass spectrometry, and the degradation process was determined. The best composite catalyst was used for the degradation of gaseous methylbenzene and gaseous acetone. The gaseous acetone degradation product was determined to be acetaldehyde via gas chromatography–mass spectrometry. The results show that the composite catalyst exhibited a good photocatalytic degradation of both liquid pollutants and harmful volatile gases. When applied to the hydrogen and oxygen evolution reactions, the composite catalyst retained a good photoresponsivity and electrolytic efficiency. Full article

In this work, the application of high-power LED_365nm and commercial, low-price LED_398nm for heterogeneous photocatalysis with TiO₂ and ZnO photocatalysts are studied and compared, focusing on the effect of light intensity, photon energy, quantum yield, electrical energy consumption, and effect of matrices and inorganic components on radical formation. Coumarin (COU) and its hydroxylated product (7-HC) were used to investigate operating parameters on the ^•OH formation rate. In addition to COU, two neonicotinoids, imidacloprid and thiacloprid, were also used to study the effect of various LEDs, matrices, and inorganic ions. The transformation of COU was slower for LED_398nm than for LED_365nm, but r₀^7-HC/r₀^COU ratio was significantly higher for LED_398nm. The COU mineralization rate was the same for both photocatalysts using LED_365nm, but a significant difference was observed using LED_398nm. The impact of matrices and their main inorganic components Cl⁻ and HCO₃⁻ were significantly different for ZnO and TiO₂. The negative effect of HCO₃⁻ was evident, however, in the case of high-power LED_365nm and TiO₂, and the formation of CO₃^•− almost doubled the r₀^7-HC and contributes to the conversion of neonicotinoids by altering the product distribution and mineralization rate. Full article

Development of efficient and affordable photocatalysts is of great significance for energy production and environmental sustainability. Transition metal chalcogenides (TMCs) with particle sizes in the 1–100 nm have been used for various applications such as photocatalysis, photovoltaic, and energy storage due to their quantum confinement effect, optoelectronic behavior, and their stability. In particular, TMCs and their heterostructures have great potential as an emerging inexpensive and sustainable alternative to metal-based catalysts for hydrogen evolution. Herein, the methods used for the fabrication of TMCs, characterization techniques employed, and the different methods of solar hydrogen production by using different TMCs as photocatalyst are reviewed. This review provides a summary of TMC photocatalysts for hydrogen production. Full article

While photocatalysis is considered a promising sustainable technology in the field of heterogeneous catalysis as well as biocatalysis, figures of merit (FOM) for comparing catalytic performance, especially between disciplines, are not well established. Here, photocatalytic water splitting was conducted using a semiconductor (NiO/La-NaTaO₃) and a bio-photocatalyst (Synechocystis sp. PCC 6803) in the same setup under similar reaction conditions, eliminating the often ill-defined influence of the setup on the FOMs obtained. Comparing the results enables the critical evaluation of existing FOMs and a quantitative comparison of both photocatalytic systems. A single FOM is insufficient to compare the photocatalysts, instead a combination of multiple FOMs (reaction rate, photocatalytic space time yield and a redefined apparent quantum yield) is superior for assessing a variety of photocatalytic systems. Full article

Making high-quality raw materials is the key to open the versatile potential of next generation materials. All-inorganic CsPbX₃ (X: Cl⁻, Br⁻, and/or I⁻) perovskite quantum dots (PQDs) have been applied in various optoelectronic devices, such as photocatalysis, hydrogen evolution, solar cells, and light-emitting diodes, due to their outstanding photophysical properties, such as high photoluminescence quantum yield (PLQY), absorption cross-section, efficient charge separation, and so on. Specifically, for further improvement of the PLQY of the PQDs, it is essential to diminish the non-radiative charge recombination processes. In this work, we approached two ways to control the non-radiative charge recombination processes through synthetic and post-synthetic processes. Firstly, we proposed how refinement of the conventional recrystallization process for PbI₂ contributes to higher PLQY of the PQDs. Secondly, after halide exchange from CsPbI₃ PQDs to CsPbBr₃, through an in situ spectroelectrochemical setup, we monitored the positive correlation between bromide deposition of on the surface of the perovskite and photoluminescence improvement of the CsPbBr₃ perovskite film through electrodeposition. These two strategies could provide a way to enhance the photophysical properties of the perovskites for application to various perovskite-based optoelectronic devices. Full article