Search Results (20)

Gallic acid (GA), a polyphenol extensively used in the food, wine, and pharmaceutical industries, is known for its inhibitory effects on soil microbial activity. Photocatalytic degradation offers an environmentally friendly solution for GA removal from water. In this work, graphitic carbon nitride (g-C₃N₄) photocatalysts were synthesized by two methods: thermal exfoliation (CN-E) and supramolecular assembly via hydrothermal processing (HCN-II). Structural analyses by XRD, FTIR, and XPS confirmed the formation of the g-C₃N₄ framework, while SEM revealed that CN-E consisted of folded and curled nanosheets, whereas HCN-II displayed a polyhedral–nanosheet hybrid architecture with internal channels. Both materials achieved approximately 80% GA degradation within 180 min under visible-light irradiation, yet HCN-II exhibited a superior apparent rate constant (k = 0.01156 min⁻¹) compared with CN-E. Radical trapping experiments demonstrated that O₂•⁻ and h⁺ were the primary reactive oxygen species involved, with OH• making a minor contribution. The enhanced performance of HCN-II is attributed to its higher surface area, improved light harvesting, and efficient charge separation derived from supramolecular assembly. These findings highlight the potential of engineered g-C₃N₄ nanostructures as efficient, metal-free photocatalysts for the degradation of recalcitrant organic pollutants in water treatment applications. Full article

A polyoxometalate-based metal–organic complex with the ability to treat pollutants in water was obtained under hydrothermal conditions, namely [Ni(H₂L)(HL)₂](PMo₁₂O₄₀)·3H₃O·4H₂O (1) (H₂L = 4,4′-(1H,1′H-[2,2′-biimidazole]-1,1′-diyl)dibenzoicacid). Structural analysis reveals that the [Ni(H₂L)(HL)₂] units are interconnected into a 2D layer via hydrogen bonds between adjacent carboxyl groups and water molecules of crystallization. [PMo₁₂O₄₀]³⁻ anions are embedded within the larger pores of the layer and are connected to the adjacent layers through hydrogen bonds, ultimately expanding the structure into a 3D supramolecular architecture. The intermolecular interactions were studied via Hirshfeld surface (HS) analysis. Electrochemical performance tests reveal that 1 exhibits electrocatalytic activity toward the oxidation and reduction of diverse pollutants in water, including NO₂⁻, Cr(VI), BrO₃⁻, Fe(III), and ascorbic acid (AA). Additionally, it can also serve as an amperometric sensor for the detection of BrO₃⁻ and Cr(VI). Photocatalytic studies reveal that compound 1 functions as a bifunctional photocatalyst, which not only achieves efficient degradation of organic dyes but also demonstrates remarkable reduction efficiency for toxic Cr(VI). Compound 1 demonstrates significant potential for practical water remediation applications. Full article

As a key means to solve energy and environmental problems, photocatalytic technology has made remarkable progress in recent years. Organic semiconductor materials offer structural diversity and tunable energy levels and thus attracted great attention. Among them, porphyrin and its derivatives show great potential in photocatalytic reactions and light therapy due to their unique large-π conjugation structure, high apparent quantum efficiency, tailorable functionality, and excellent biocompatibility. Compared to unassembled porphyrin molecules, supramolecular porphyrin assemblies facilitate the solar light absorption and improve the charge transfer and thus exhibit enhanced photocatalytic performance. Herein, the research progress of porphyrin-based supramolecular assemblies, including the construction, the regulation of charge separation and transfer, stability, and application in photocatalysis, was systematically reviewed. The construction strategy of porphyrin supramolecules, the mechanism of charge separation, and the intrinsic relationship of assembling structure-charge transfer-photocatalytic performance received special attention. Surfactants, peptide molecules, polymers, and metal ions were introduced to improve the stability of the porphyrin assemblies. Donor-acceptor structure and co-catalysts were incorporated to inhibit the recombination of the photoinduced charges. These increase the understanding of the porphyrin supramolecules and provide ideas for the design of high-performance porphyrin-based photocatalysts. Full article

Photocatalytic degradation of organic pollutants is one of the green ways to solve environmental problems. In this study, the PDI-COOH/PDINH composite photocatalysts were successfully synthesized by electrostatic self-assembly. Under visible light irradiation, the degradation efficiency of the optimal PDI-COOH/PDINH sample reached 67%, which was 1.7 and 1.6 times higher than that of the self-assembled PDINH supramolecule and PDI-COOH supramolecule, respectively. The excellent photocatalytic performance of PDI-COOH/PDINH can be attributed to the enhancement of the separation and transport efficiency of photogenerated carriers by the construction of a heterojunction and the expanded electronic conjugated structure by the combination of organic–organic semiconductors. This study offers a new idea for the preparation of organic–organic composite photocatalysts. Full article

The development of efficient and environmentally friendly photocatalysts is crucial for addressing global energy and environmental challenges. Perylene diimide, an organic supramolecular material, holds great potential for applications in mineralized phenol. In this study, through the integration of different mass ratios of unmodified perylenimide (PDI-NH) into the self-assembly of amino acid-substituted perylenimide (PDI-COOH), a novel supramolecular organic heterojunction (PDICOOH/PDINH) was fabricated. The ensuing investigation focuses on its visible-light mineralized phenol properties. The results show that the optimal performance is observed with a composite mass fraction of 10%, leading to complete mineralization of 5 mg/L phenol within 5 h. The reaction exhibits one-stage kinetics with rate constants 13.80 and 1.30 times higher than those of PDI-NH and PDI-COOH, respectively. SEM and TEM reveal a heterogeneous interface between PDI-NH and PDI-COOH. Photoelectrochemical and Kelvin probe characterization confirm the generation of a built-in electric field at the interface, which is 1.73 times stronger than that of PDI-COOH. The introduction of PDI-NH promotes π-π stacking of PDI-COOH, while the built-in electric field facilitates efficient charge transfer at the interface, thereby enhancing phenol decomposition. The finding demonstrates that supramolecular heterojunctions have great potential as highly effective photocatalysts for environmental remediation applications. Full article

Photocatalysis based on titanium dioxide (TiO₂) has become a promising method to remediate industrial and municipal effluents in an environmentally friendly manner. However, the efficiency of TiO₂ is hampered by problems such as rapid electron–hole recombination and limited solar spectrum absorption. Furthermore, the sensitization of TiO₂ through heterojunctions with other materials has gained attention. Vanadium, specifically in the form of ammonium vanadate ((NH₄)₂V₃O₈), has shown promise as a photocatalyst due to its ability to effectively absorb visible light. However, its use in photocatalysis remains limited. Herein, we present a novel synthesis method to produce lamellar (NH₄)₂V₃O₈ as a sensitizer in a supramolecular hybrid photocatalyst of TiO₂–stearic acid (SA), contributing to a deeper understanding of its structural and magnetic characteristics, expanding the range of visible light absorption, and improving the efficiency of photogenerated electron–hole separation. Materials, such as TiO₂–SA and (NH₄)₂V₃O₈, were synthesized and characterized. EPR studies of (NH₄)₂V₃O₈ demonstrated their orientation-dependent magnetic properties and, from measurements of the angular variation of g-values, suggest that the VO₂⁺ complexes are in axially distorted octahedral sites. The photocatalytic results indicate that the 2D/2D heterojunction layered TiO₂/vanadate at a ratio (1:0.050) removed 100% of the methylene blue, used as a model contaminant in this study. The study of the degradation mechanism of methylene blue emphasizes the role of reactive species such as hydroxyl radicals (^•OH) and superoxide ions (O₂^•−). These species are crucial for breaking down contaminant molecules, leading to their degradation. The band alignment between ammonium vanadate ((NH₄)₂V₃O₈) and TiO₂–SA, shows effective separation and charge transfer processes at their interface. Furthermore, the study confirms the chemical stability and recyclability of the TiO₂–SA/(NH₄)₂V₃O₈ photocatalyst, demonstrated that it could be used for multiple photocatalytic cycles without a significant loss of activity. This stability, combined with its ability to degrade organic pollutants under solar irradiation, means that the TiO₂–SA/(NH₄)₂V₃O₈ photocatalyst is a promising candidate for practical environmental remediation applications. Full article

Photocatalysis technology is an economical and effective new energy technology which depends on the conversion and storage of light energy through an energy transfer process or charge transfer process. Recently, organic semiconductor photocatalytic materials with the advantages of controllable structure, broad spectral response, designability, and flexibility have received wide attention. In particular, the organic polymeric materials containing poly-perylene diimides (PDI) show significant promise in the realm of photocatalysis due to their impressive catalytic capabilities and wide spectral reactivity. However, a poor charge separation and transportation (CST) process undermines their photocatalytic efficiency in most polymer photocatalysts, as well as in PDI photocatalysts. In this context, we propose a new strategy through regulating the monomer symmetry to construct highly efficient PDI photocatalysts. As proof-of-concept, a series of new PDI-based organic supramolecular photocatalytic materials with full visible spectral response from the perspectives of both the π-π conjugated structure and the symmetry of chain structure are successfully synthesized. Meanwhile, the structural compositions, morphology features, electrical properties, and photocatalytic performances of those obtained PDI photocatalysts were systematically studied. The results shown that the as-prepared PDI-1,5NDA exhibits 1.6-fold and 3.7-fold higher levels of photosynthesis of H₂O₂ activity than those of PDI-1,4NDA and PDI-PDA, respectively, which could be ascribe to its lower symmetry and large π-conjugate systems greatly enhances the separation of charge carriers. Full article

Coordination polymers (CPs) are an assorted class of coordination complexes that are gaining attention for the safe and sustainable removal of organic dyes from wastewater discharge by either adsorption or photocatalytic degradation. Herein, three different coordination polymers with compositions [Ni(HL)(H₂O)₂·1.9H₂O] (1), [Mn₃(HL)(L)(μ₃-OH)(H₂O)(phen)₂·2H₂O] (2), and [Cd(HL)₄(H₂O)]·H₂O (3) (H₃L = 2-(3,5-dicarboxyphenyl)-6-carboxybenzimidazole; phen = 1,10-phenanthroline) have been synthesized and characterized spectroscopically and by single crystal X-ray diffraction. Single crystal X-ray diffraction results indicated that 1 forms a 2D layer-like framework, while 2 exhibits a 3-connected net with the Schläfli symbol of (4⁴.6), and 3 displays a 3D supramolecular network in which two adjacent 2D layers are held by π···π interactions. All three compounds have been used as photocatalysts to catalyze the photodegradation of antibiotic dinitrozole (DTZ) and rhodamine B (RhB). The photocatalytic results suggested that the Mn-based CP 2 exhibited better photodecomposition of DTZ (91.1%) and RhB (95.0%) than the other two CPs in the time span of 45 min. The observed photocatalytic mechanisms have been addressed using Hirshfeld surface analyses. Full article

Graphitized carbon nitride (g-C₃N₄), as a metal-free, visible-light-responsive photocatalyst, has a very broad application prospect in the fields of solar energy conversion and environmental remediation. The g-C₃N₄ photocatalyst owns a series of conspicuous characteristics, such as very suitable band structure, strong physicochemical stability, abundant reserves, low cost, etc. Research on the g-C₃N₄ or g-C₃N₄-based photocatalysts for real applications has become a competitive hot topic and a frontier area with thousands of publications over the past 17 years. In this paper, we carefully reviewed the recent advances in the synthesis and structural design of g-C₃N₄ materials for efficient photocatalysts. First, the crucial synthesis parameters of g-C₃N₄ were fully discussed, including the categories of g-C₃N₄ precursors, reaction temperature, reaction atmosphere and reaction duration. Second, the construction approaches of various nanostructures were surveyed in detail, such as hard and soft template, supramolecular preorganization and template-free approaches. Third, the characteristics of different exfoliation methods were compared and summarized. At the end, the problems of g-C₃N₄ materials in photocatalysis and the prospect of further development were disclosed and proposed to provide some key guidance for designing more efficient and applicable g-C₃N₄ or g-C₃N₄-based photocatalysts. Full article

In this study, Fe-doped graphitic carbon nitride (Fe-MCNC) with varying Fe contents was synthesized via a supramolecular approach, followed by thermal exfoliation, and was then used for accelerated photocatalytic hydrogen evolution and nitrogen fixation. Various techniques were used to study the physicochemical properties of the MCN (g-C₃N₄ from melamine) and Fe-MCNC (MCN for g-C₃N₄ and C for cyanuric acid) catalysts. The field emission scanning electron microscopy (FE-SEM) images clearly demonstrate that the morphology of Fe-MCNC changes from planar sheets to porous, partially twisted (partially developed nanotube and nanorod) nanostructures. The elemental mapping study confirms the uniform distribution of Fe on the MCNC surface. The X-ray photoelectron spectroscopy (XPS) and UV-visible diffuse reflectance spectroscopy (UV-DRS) results suggest that the Fe species might exist in the Fe³⁺ state and form Fe-N bonds with N atoms, thereby extending the visible light absorption areas and decreasing the band gap of MCN. Furthermore, doping with precise amounts of Fe might induce exfoliation and increase the specific surface area, but excessive Fe could destroy the MCN structure. The optimized Fe-MCNC nanostructure had a specific surface area of 23.6 m² g⁻¹, which was 8.1 times greater than that of MCN (2.89 m² g⁻¹). To study its photocatalytic properties, the nanostructure was tested for photocatalytic hydrogen evolution and nitrogen fixation; 2Fe-MCNC shows the highest photocatalytic activity, which is approximately 13.3 times and 2.4 times better, respectively, than MCN-1H. Due to its high efficiency and stability, the Fe-MCNC nanostructure is a promising and ideal photocatalyst for a wide range of applications. Full article

A novel phosphorus and oxygen co-doped graphitic carbon nitride (_sheetP-O-CN_SSA) photocatalyst was successfully synthesized and applied for H₂ evolution under visible light. In the synthesis process of _sheetP-O-CN_SSA, the supramolecular complex was developed by the self-assembly and copolymerization reaction among melamine, cyanuric acid (CA) and trithiocyanuric acid (TCA) to act as g-C₃N₄ precursors, while (NH₄)₂HPO₄ was applied as P and O precursors for element doping. The chemical structures, morphologies, and optical properties of the _sheetP-O-CN_SSA were characterized by a series of measurements, i.e., XRD, FT-IR, SEM, TEM, UV-vis DRS, and PL. The results suggested that the introduction of P and O elements could enhance the separation and migration efficiency of photogenerated electrons and holes in the energy band of g-C₃N₄. The photocatalytic tests over Erythrosin B (EB) sensitized _sheetP-O-CN_SSA indicated that the hydrogen evolution was greatly enhanced compared with other catalysts and non-sensitized _sheetP-O-CN_SSA under visible light irradiation. Finally, a possible dye-sensitized photocatalysis mechanism was also proposed on the basis of the as-obtained results. Full article

Two robust Sn(IV)-porphyrin-based supramolecular arrays (1 and 2) were synthesized via the reaction of trans-Pd(PhCN)₂Cl₂ with two precursor building blocks (SnP¹ and SnP²). The structural patterns in these architectures vary from 2D to 3D depending on the axial ligation of Sn(IV)-porphyrin units. A discrete 2D tetrameric supramolecule (1) was constructed by coordination of {(trans-dihydroxo)[5,10-bis(4-pyridyl)-15,20-bis(phenyl) porphyrinato]}tin(IV) (SnP¹) with trans-PdCl₂ units. In contrast, the coordination between the {(trans-diisonicotinato)[5,10-bis(4-pyridyl)-15,20-bis(phenyl)porphyrinato]}tin(IV) (SnP²) and trans-PdCl₂ units formed a divergent 3D array (2). Axial ligation of the Sn(IV)-porphyrin building blocks not only alters the supramolecular arrays but also significantly modifies the nanostructures, including porosity, surface area, stability, and morphology. These structural changes consequently affected the photocatalytic degradation efficiency under visible-light irradiation towards acid orange 7 (AO) dye in an aqueous solution. The degradation efficiency of the AO dye in the aqueous solution was observed to be between 86% to 91% within 90 min by these photocatalysts. Full article

C₃N₄ is an innovative material that has had huge success as a photocatalyst in recent years. More recently, it has been coupled to robust metal oxides to obtain more stable materials. This work is focused on the different synthesis techniques used to prepare bare C₃N₄ and combined C₃N₄/ZnO mixed systems. Different precursors, such as pure melamine and cyanuric acid-based supramolecular complexes, were employed for the preparation of the C₃N₄ material. Moreover, different solvents were also used, demonstrating that the use of water leads to the formation of a more stable heterojunction. Structural (XRD), morphological (FESEM) and optical (UV-vis) measurements underlined the role of the precursors used in the preparation of the materials. A clear trend can be extrapolated from this experimental approach involving different intimate contacts between the two C₃N₄ and ZnO phases, strictly connected to the particular preparation method adopted. The use of the supramolecular complexes for the preparation of C₃N₄ leads to a tighter association between the two phases at the heterojunction, resulting in much higher visible light harvesting (connected to lower band gap values). Full article

The desire to harness solar energy to address current global environmental problems led us to investigate two-dimensional (2D) core–shell hybrid photocatalysts in the form of a 2D-TiO₂–surfactant, mainly composed of fatty acids. The bulk products, prepared by two slightly different methods, consist of stacked host–guest hybrid sheets held together by van der Waals forces between alkyl carboxylate moieties, favoring the synergistic conjugation of the photophysical properties of the core and the hydrophobicity of the self-assembled surfactant monolayer of the shell. X-ray diffraction and the vibrational characteristics of the products revealed the influence of synthesis strategies on two types of supramolecular aggregates that differ in the core chemical structure, guest conformers of alkyl surfactant tails and type, and the bilayer and monolayer of the structure of nanocomposites. The singular ability of the TiO₂ core to anchor carboxylate leads to commensurate hybrids, in contrast to both layered clay and layered double-hydroxide-based ion exchangers which have been previously reported, making them potentially interesting for modeling the role of fatty acids and lipids in bio-systems. The optical properties and photocatalytic activity of the products, mainly in composites with smaller bandgap semiconductors, are qualitatively similar to those of nanostructured TiO₂ but improve their photoresponse due to bandgap shifts and the extreme aspect-ratio characteristics of two-dimensional TiO₂ confinement. These results could be seen as a proof-of-concept of the potential of these materials to create custom-designed 2D-TiO₂–surfactant supramolecular photocatalysts. Full article

Colloidal dye-sensitized photocatalysis is a promising route toward efficient solar fuel production by merging properties of catalysis, support, light absorption, and electron mediation in one. Metal-organic frameworks (MOFs) are host materials with modular building principles allowing scaffold property tailoring. Herein, we combine these two fields and compare porous Zr-based MOFs UiO-66-NH₂(Zr) and UiO-66(Zr) to monoclinic ZrO₂ as model colloid hosts with co-immobilized molecular carbon dioxide reduction photocatalyst fac-ReBr(CO)₃(4,4′-dcbpy) (dcbpy = dicarboxy-2,2′-bipyridine) and photosensitizer Ru(bpy)₂(5,5′-dcbpy)Cl₂ (bpy = 2,2′-bipyridine). These host-guest systems demonstrate selective CO₂-to-CO reduction in acetonitrile in presence of an electron donor under visible light irradiation, with turnover numbers (TONs) increasing from ZrO₂, to UiO-66, and to UiO-66-NH₂ in turn. This is attributed to MOF hosts facilitating electron hopping and enhanced CO₂ uptake due to their innate porosity. Both of these phenomena are pronounced for UiO-66-NH₂(Zr), yielding TONs of 450 which are 2.5 times higher than under MOF-free homogeneous conditions, highlighting synergistic effects between supramolecular photosystem components in dye-sensitized MOFs. Full article