Perylene diimide supermolecule (PDI) as a novel and highly efficient cocatalyst for photocatalytic degradation of tetracycline in water: A case study of PDI decorated graphitic carbon nitride/bismuth tungstate composite

Lignocellulosic herbal waste-derived hydrochar composites for activating peroxodisulfate in visible light photocatalytic degradation of minocycline

The photocatalytic system was developed through the self-assembly of lignocellulosic-based waste Panax notoginseng residue converted into hydrochar (PHC) with the organic semiconductor perylene diimide (PDI) to facilitate the visible-light photocatalytic degradation of minocycline hydrochloride (Mino-HCl) with the assistance of peroxodisulfate (PDS). The optimal PHC/PDI ratio of 1:4 was selected for further experiments, achieving 90.8 % minocycline removal under visible light after 2 h. At the optimal ratio, the visible light photocatalytic performance of PHC/PDI composites under PDS activation was 5.18 and 8.61 times higher than that of PDI and PHC, respectively. The system also exhibited excellent mineralization of minocycline, with a mineralization rate of 73.7 %. The PHC/PDI/PDS (P-P-P) system demonstrated good stability under visible light and showed general adaptability to different environmental conditions, including pH, coexisting anions and cations, and real water matrix. Theoretical calculations identified the O5, O7, N9, C20 and C29 sites of Mino-HCl as key targets for free radical attack. Toxicity assessments indicated significant reductions in both acute and chronic toxicity, particularly for fish and algae, indicating the transformation of Mino-HCl into less harmful products. This work provided a theoretical basis and reference for the research on waste management and wastewater treatment by employing lignocellulosic-based waste residues converted into biochar and an organic semiconductor PDI composite under PDS activation for visible light photocatalysis.

Self-Assembled Perylenediimide Nanoaggregates with an Alternate Stringlike Morphology as Photoanodes to Enhance the H2O2 Photoelectrochemical Cell Performance

A self-assembled supramolecular photocatalyst of benzoic acid-substituted perylenediimide (SA-BAPDI) is successfully prepared, forming an alternate stringlike morphology driven by intermolecular hydrogen-bonding and π-π interactions. This unusual morphology induces a strong built-in electric field and an enormous π-conjugated effect, which can promote efficient separation of photogenerated carriers. Meanwhile, SA-BAPDI photocatalyst applied as the photoanode in the H2O2 photoelectrochemical cell for the first time can facilitate photocatalytic H2O2 production by water oxidation, which can be used as fuel to generate electricity through redox reactions and further to achieve solar-chemical-electrical energy conversion. The SA-BAPDI-based cell displays the maximum light power density of 1.06 mW·cm-2 and the specific capacitance of 5025 mF·cm-2 after 0.5 h of irradiation, which can still retain the original value of 50% in the dark for 12 h of continuous operation. This study verifies that morphology regulation of self-assembled perylenediimide supramolecular photocatalytic materials benefits the design and development of a high-performance H2O2 photoelectrochemical cell.

Novel PDI-NH/PDI-COOH Supramolecular Junction for Enhanced Visible-Light Photocatalytic Phenol Degradation

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.

Rational construction of visible-light-driven perylene diimides/Fe2O3@C derived from MIL-88A (Fe) heterojunction with S-scheme electron transfer pathway to activate peroxymonosulfate for degradation of antibiotics

The novel composite photocatalytic material perylene diimides/Fe2O3@C (PDIs/Fe2O3@C) was constructed by a simple hydrothermal-calcination method and an oil bath method. 20 % PDIs/Fe2O3@C displayed a 16.4-fold increase in the rate of tetracycline (TC) removal over Fe2O3@C at 8 min. The main factor that enhanced photocatalytic performance was due to the combination of PDIs with Fe2O3@C, which effectively improved the phenomenon during the self-assembly of highly agglomerative PDIs, increased the specific surface area of Fe2O3@C, exposed more reaction sites, and promoted the activation of peroxymonosulfate (PMS) by Fe2+/Fe3+; and secondly, the composite of two different materials, both organic and inorganic, which effectively promoted the photogenerated electron transfer and the separation of electron-hole pairs, the a new S-scheme electron transport pathway is formed, which effectively promoted the photogenerated electron transfer as well as the e--h+ separation, which was more favorable for the activation of PMS. The whole reaction pathway and product toxicity were thoroughly evaluated by Fukui function calculations, Liquid Chromatograph Mass Spectrometer (LC-MS), and Toxicity Estimation Software Tool (T.E.S.T.) simulation results, which demonstrated the rationality of the degradation pathway and the greatly reduced product toxicity. Moreover, the composites were effective and versatile for all other antibiotics (chlortetracycline (CTC), ciprofloxacin (CIP) and sulfadiazine (SDZ)). As an advanced oxidation process, the activation of PDIs/Fe2O3@C under visible light shows its potential application in pollutant degradation, which provides new perspectives and ideas for further effective treatment of real wastewater.

Enhancing Pollutant Mineralization through Organic-Inorganic Defect-Transit Dual S-scheme with a Robust Internal Electric Field

Achieving superior photomineralization of pollutants relies on a rational design of a dual S-scheme with a robust internal electric field (IEF). In this study, to tackle the low mineralization rate in type-II In2 O3 /In2 S3 (IO/IS) systems, an organic-inorganic dual S-scheme In2 O3 /PDI/In2 S3 (IO/PDI/IS) nanostructured photocatalyst is synthesized via a method combining solvent-induced self-assembly and electrostatic forces. Due to the unique energy band position and strong IEF, the photoinduced defect-transit dual S-scheme IO/PDI/IS facilitates the degradation of lignin and antibiotics. Notably, a promising mineralization rate of 80.9% for sodium lignosulfonate (SL) is achieved. The charge transport pathway of IO/PDI/IS are further validated through the analysis of in situ X-ray photoelectron spectroscopy (in situ XPS), density functional theory calculations, and radical trapping experiments. In-depth, two possible pathways for the photocatalytic degradation of lignin are proposed based on the intermediates monitored by liquid chromatography-mass spectrometry (LC-MS). This study presents a new strategy for the design of organic-inorganic dual S-scheme photocatalysts with a robust IEF for pollutant degradation.

Study on the behavior and mechanism of NiFe-LDHs used for the degradation of tetracycline in the photo-Fenton process

An environment-friendly 3D NiFe-LDHs photocatalyst was fabricated via a simple hydrothermal method and characterized by means of SEM, XRD, BET, XPS and FT-IR. It is a highly efficient heterogeneous photo-Fenton catalyst for the degradation of TC-HCl under visible light irradiation. After exploring the effects of catalyst dosage, initial concentration of TC-HCl, solution pH and H2O2 concentrations, the optimal reaction conditions were determined. The experiment results showed that the degradation efficiency can reach 99.11% through adding H2O2 to constitute a photo-Fenton system after adsorption for 30 min and visible light for 60 min. After four cycles, the degradation rate decay is controlled within 21.2%, indicating that NiFe-LDHs have excellent reusable performance. The experimental results of environmental factors indicate that Fe2+ and Ca2+ promoted the degradation of TC-HCl, both Cl- and CO32- inhibited the degradation of TC-HCl. Two other antibiotics (OTC and FT) were selected for research and found to be effectively removed in this system, achieving effective degradation of a variety of typical new pollutants. The radical trapping tests and ESR detection showed that ·OH and ·O2- were the main active substances for TC degradation in the photo-Fenton system. By further measuring the intermediate products of photodegradation, the degradation pathway of TC-HCl was inferred. The toxicity analysis demonstrated that the overall toxicity of the identified intermediates was reduced in this system. This study provides a theoretical and practical basis for the removal of TC in aquatic environments.

Heterojunction Photocatalyst Loaded on Electrospun Nanofibers for Synergistic Enhanced Photocatalysis and Real-Time Temperature Monitoring

Bi2WO6:Ho3+, Yb3+/g-C3N4 (BHY/CN) photocatalysts are successfully loaded on polyacrylonitrile (PAN) nanofibers by electrospinning technology, which combines an upconversion effect and heterojunctions to achieve dual-functional characteristics. Polymer-modified photocatalytic materials offer a large specific surface area of 24.1 m2/g and a pore volume of 0.1 cm3/g, promoting the utility of solar energy. The introduction of rare earth ions and g-C3N4 optimizes the structural band gap, which broadens the light absorption range and promotes electron transfer. Moreover, the heterojunction between Bi2WO6 and g-C3N4 has suppressed the complexation of photoinduced carriers, further improving catalytic performance. The optimized photocatalysts have higher photocatalytic activity with degrading 92.6% tetracycline-hydrochloride (120 min) under simulated sunlight irradiation. The optical thermometry has also been achieved based on the fluorescence intensity ratio technique, where the maximum absolute and relative sensitivity values of BHY/CN-1:6@PAN are 3.322% K-1 and 0.842% K-1, respectively. This dual-functional nanofibers with excellent mechanical properties provide noncontact temperature feedback and efficient catalytic performance for better wastewater treatment and ecological restoration in extreme harsh environments.

Perylene diimide/iron phthalocyanine Z-scheme heterojunction with strong interfacial charge transfer through π-π interaction: Efficient photocatalytic degradation of tetracycline hydrochloride

The development of an all-organic Z-scheme heterojunction photocatalyst with the matched band structure, efficient electron transfer and excellent photocatalytic performance is valuable for a sustainable future. A novel perylene diimide/phthalocyanine iron (PDI/FePc) heterojunctions with strong π-π interaction were synthesized by a self-assembled method, which exhibited strong visible-light-driven photocatalytic degradation activities of tetracycline hydrochloride (TC). The TC removal rate over PDI/FePc was achieved three times and 87.5 times higher than that of PDI and FePc. PDI/FePc (131.1 mv·dec^-1) presented a lower Taffel slope than that of PDI (228.6 mv·dec^-1) for the oxidation. This may be due to the strong π-π interactions between PDI and FePc, which can reduce the layer spacing of the supramolecular structure and facilitate the separation and transfer of photogenerated carriers in the built-in electric field. In addition, radical quenching tests revealed that superoxide radicals (•O₂^-) acted as a dominant role in photocatalytic oxidation. An increscent specific surface area of PDI decorated by FePc also gave the rapid pathway for charge transfer and enhanced the adsorption ability. This provides a new idea for the formation of heterojunction to improve the photocatalytic activity of organic supramolecular materials.

Incorporating Fe, Co co-doped graphene with PDI supermolecular for promoted photocatalytic activity: A story of electron transfer

Iron-cobalt dual single-atom anchoring on nitrogen-doped graphene (Fe_xCo_y-NG) improves the efficiency of migration and separation of photo-generated carriers. In this work, the perylene diimide (PDI) is self-assembled on the Fe_xCo_y-NG to form the Fe_xCo_y-NG/PDI composites by π-π interaction, which is reported for the first time. The bisphenol A (BPA) degradation of optimized 20% Fe_0.2Co_0.8-NG/PDI are nearly 100%, and the degradation rate is 1.5 and 12.7 times that of the self-assembled PDI and commercial-grade PDI. The high degradation performance by Fe_xCo_y-NG/PDI are mainly due to: (i) regulating the proportion of Fe-Co dual active sites content, so that it can achieve the synergistic interaction to facilitate the transfer of electrons in the catalytic reaction. (ii) PDI is uniformly dispersed by adding the Fe_xCo_y-NG, which increases the specific surface area of composites to adsorb more pollutants. Free radical trapping experiments and electron spin-resonance spectroscopy characterization confirmed that the O₂^-, OH, ¹O₂ and h⁺ are the main reactive species (RSs) for BPA degradation. Under the attack of RSs, BPA completes the processes of hydroxylation, demethylation, aromatization, ring-opening, and finally complete mineralization into CO₂ and H₂O. These results revealed that Fe_0.2Co_0.8-NG/PDI photocatalysts may be efficiently applied for the remediation of phenol contaminated natural waters.

Cu0@CuOx-NC modified Zn2In2S5 for photo-self-Fenton system coupling H2O2 in-situ production and decomposition

Although many concerns have been put into photocatalytic hydrogen peroxide (H₂O₂) production, multifunctional catalysis suitable for continuously in-situ H₂O₂ consumption in the field has rarely been investigated. Herein, Cu⁰@CuO_x@nitrogen-doped graphitic carbon (Cu⁰@CuO_x-NC) decorated Zn₂In₂S₅ was successfully prepared for in-situ production and activation H₂O₂, which could achieve effectively photocatalytic self-Fenton degradation of tetracycline (TC). Under visible light irradiation, 5wt% Cu⁰@CuO_x-NC/Zn₂In₂S₅ (CuZS-5) efficiently generated a high yield of H₂O₂ (0.13 mmol L^-1), and Cu⁰@CuO_x-NC could in-situ consume H₂O₂ to generate hydroxyl radicals (•OH), accelerating the oxidation of TC. As a result, the 5 wt% Cu⁰@CuO_x-NC/Zn₂In₂S₅ degraded about 89.3% of TC within 60 min, and the cycle experiments also exhibited sufficient stability. This study achieves a delicate combination of in-situ production and activation of H₂O₂, which is regarded as a promising strategy to eco-friendly promote pollutant degradation in wastewater.

Designed Synthesis of PDI/BiOCl-BiPO4 Composited Material for Boosted Photocatalytic Contaminant Degradation

Enhancing the photocatalytic performance for contaminant degradation to accelerate the large-scale application of photocatalysis still is an enduring challenge. Herein, ternary PDI/BiOCl-BiPO4 composited materials with the different contents of PDI were designed and constructed by the multi-step compound method. The tetracycline hydrochloride and rhodamine B were chosen as targeted pollutants to investigate the photocatalytic performance of PDI/BiOCl-BiPO4 composited materials. The structure and component of BiOCl-BiPO4 and PDI/BiOCl-BiPO4 samples were detailedly characterized by a sequence of physical and chemical characterizations. The optimized PDI/BiOCl-BiPO4 sample, namely PDI(5%)/BiOCl-BiPO4, exhibited the excellent photocatalytic activity for tetracycline hydrochloride and rhodamine B degradation. The major active species that were holes (h+) and superoxide radicals (•O2−) also can be determined in the photocatalytic degradation process by active species trapping experiments. Furthermore, the photoelectrochemical and fluorescence measurements manifest the crucial role of PDI material. It can reduce the recombination of photo-excited charge carrier and improve the separation and transfer of photo-generated electron-hole pairs, which is beneficial to the photocatalytic reaction process. It is anticipated that our work would provide a counterpart to prepare the high-efficiency composited material in heterogeneous photocatalysis.

Fabrication of hydrangea-shaped Bi2WO6/ZIF-8 visible-light responsive photocatalysts for degradation of methylene blue

In this paper, the hydrangea-shaped Bi₂WO₆/ZIF-8 (BWOZ) visible light photocatalysts have been prepared via a facile synthetic strategy for the first time. The constructed BWOZ composites were systematically studied by a series of characterization techniques. The SEM results manifested the octahedral ZIF-8 coated the flower-like Bi₂WO₆ uniformly and the composition of BWOZ composites had been confirmed by XPS measurement. And the photocatalytic activity was evaluated by eliminating methylene blue with the help of visible light. The results showed that 7%-BWOZ (7.0 wt% Bi₂WO₆) exhibited better photodegradation capability than pure Bi₂WO₆ and ZIF-8. Compared with Bi₂WO₆, the photocatalytic degradation of methylene blue by 7%-BWOZ could reach 85.7%. In addition, the pseudo-first-order kinetic constant of 7%-BWOZ was 23.00 and 1.61 times that of pristine Bi₂WO₆ and ZIF-8, respectively. The improved photocatalytic ability of BWOZ systems may be due to the construction of heterojunctions between Bi₂WO₆ and ZIF-8, which resulted in the rapid separation of photogenerated carriers. Additionally, the specific surface area of the formed BWOZ system was also improved in comparison with the flower-shaped Bi₂WO₆, and thus more active sites could be provided to contact with methylene blue molecules, thereby achieving better removal capacity. Moreover, trapping experiments and electron spin resonance results further illustrated that the coexistence of multiple free radicals realized efficient degradation of methylene blue. More importantly, the photocatalytic property of the 7%-BWOZ composite remained even after three cycles. Furthermore, a feasible photodegradation mechanism was also explored in depth.