FeOOH Quantum Dots Research Articles

Porous fluorine-cerium nanosheets anchored with FeOOH quantum dots for synergistic enhanced visible-light-driven photo-Fenton degradation of phenol

The utilization of two-dimensional (2D) materials to construct heterogeneous catalysts provides opportunities for environmental remediation, while the incorporation of porous structures can further enhance catalytic performance. In this work, a porous 2D FeOOH/fluorine-cerium (F-Ce) nanosheet composite was designed and synthesized by a simple impregnation-precipitation method. The unique 2D porous structure of F-Ce promoted the high dispersion of FeOOH quantum dots (QDs) (∼1.4 nm) and their tight integration to form S-scheme heterojunctions. This structure offered a greater number of active sites, and significantly improved the capacity of light absorption and the separation and migration efficiency of photogenerated carriers, thus improving catalytic activity. This catalyst achieved a phenol removal rate of 98.1 % within 20 min during the photo-Fenton reaction, which significantly surpasses pure FeOOH (32.9 %) and F-Ce (21.7 %) alone. In particular, the optimized 14FeOOH/F-Ce catalyst achieved more than 95.0 % degradation efficiency within a remarkably short period of 5 min. Mott Schottky and in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) studies demonstrated that the S-scheme charge transfer mechanism of this heterojunction synergistically enhanced the catalytic activity of the Fenton-like reaction. This study provides valuable insights for designing efficient 2D porous heterojunction catalysts for visible-light-driven Fenton applications.

Graphitic carbon nitride loaded with FeOOH quantum dots for synergistic photocatalysis-Fenton inactivation of pathogenic marine bacteria: Mechanisms and coupling coefficients

Sustainable and environmental benign technologies for inactivation of pathogenic marine bacteria in ballast water remains a challenge. Herein, graphitic carbon nitride (g-C3N4) loaded with FeOOH quantum dots (QDs) were fabricated and a synergistic photocatalysis-Fenton system was established, which inactivated Vibrio alginolyticus (7 log) in ballast water within 30 min under visible light irradiation. The bacterial inactivation rate constant in the coupling system was 26.5 and 6.6 times higher than traditional photocatalysis and Fenton system, respectively, exhibiting 88.8 % of synergistic coupling coefficient. The bactericidal efficiency remained consistent across varying pH levels, allowing direct application of this method in alkaline marine conditions. Free radicals including OH and O2− were proved to be the predominant contributors in the coupling system. The loading of FeOOH QDs could upshift conduction band potential of g-C3N4, thus photogenerated electrons were more easily trapped by O2 to enhance the separation of charge carriers. The photogenerated electrons also accelerated the faster circulation of Fe(III)/Fe(II), which further inhibited electron-hole recombination. Furthermore, bacterial inactivation mechanisms were elucidated by examining total protein changes, intracellular ROSs level and enzyme activities. This work offers innovative approaches for marine bacterial inactivation and ballast water disinfection, which can also find applications in other environmental-related fields.

Novel FeOOH-decorated La-doped Bi4O5I2 microspheres for boosting photocatalysis-Fenton synergy degradation of emerging contaminants

Photocatalytic-Fenton synergistic degradation of pollutants in wastewater is considered a promising technology for environmental treatment. Herein, FeOOH quantum dots decorated La-doped Bi4O5I2 hybrids were prepared using an in-situ deposition strategy and applied for the removal of 2,4-dinitrophenylhydrazine. The FeOOH-1/La10-Bi4O5I2 sample exhibits the highest catalytic activity in degradation experiments, eliminating 93.8 % of 2,4-dinitrophenylhydrazine within 30 min at a reaction rate constant of 0.117 min−1. In addition, the impacts of several operational parameters on the catalytic activity were comprehensively examined, including H2O2 concentration, catalyst dosage, reaction solution pH and co-existing ions. In degradation process of 2,4-dinitrophenylhydrazine, the major reactive oxygen species are ·OH and ·O2–, with ·OH generated by Fenton reaction. Optical property characterization, cyclic voltammetry tests, and photoelectrochemical measurements confirmed that the FeOOH-1/La10-Bi4O5I2 composite has excellent light absorption capacity, abundant active centers, and excellent carrier separation efficiency. Finally, the degradation mechanism of FeOOH-1/La10-Bi4O5I2 composites for 2,4-dinitrophenylhydrazine is rationally discussed based on experimental and theoretical calculations. This study presents a fresh design idea for developing bismuth oxyhalide-based composites with high activity.

Biocompatibility FeOOH QD@ATP-BODIPY nanocomposite for glutathione detection and intracellular imaging

Monitoring of glutathione has attracted considerable attention owing to its biological and clinical significance. An eco-friendly, economic, simple, biocompatible probe with excellent sensitivity and selectivity is very important. Herein, FeOOH QD@ATP-BODIPY nanocomposite was fabricated from one-step synthesized FeOOH quantum dots (FeOOH QD) and commercial boron-dipyrromethene-conjugated adenosine 5′-triphosphate (ATP-BODIPY) for glutathione (GSH) sensing in solutions and living cells. Three fascinate merits of FeOOH QD were confirmed: (a) as fluorescence quencher for ATP-BODIPY, (b) as selective recognizer of GSH and (c) with carrier effects and membrane permeability. The construction and response mechanism of the nanocomposite was based on the competitive coordination chemistry and redox reaction of FeOOH QD between GSH and phosphate group of ATP-BODIPY. Under the optimal conditions, the detection limit for GSH was as low as 68.8 nM. Excellent linear range of 0.2–400 μM was obtained. Furthermore, the chemical response of the nanocomposite exhibits high selectivity toward GSH over other electrolytes and biomolecules. It was successfully applied for GSH determination in human serum samples. The MTT assay exhibited FeOOH QD@ATP-BODIPY nanocomposite own good biocompatibility. FeOOH QD@ATP-BODIPY respond to GSH in living cells in situ was also proved via fluorescence imaging. These suggested that the FeOOH QD@ATP-BODIPY nanocomposite had potential application in biological and clinical applications.

Two‐Dimensional BiOBr Nanosheets Coupled with FeOOH Quantum Dots as Composite Photo‐Fenton Catalysts for Organic Pollutant Degradation under Visible Light

AbstractFeOOH quantum dots (QDs) were successfully anchored on 2D BiOBr nanosheets as composite photo‐Fenton catalysts by a simple precipitation and impregnation method. Using Rhodamine B (RhB) as an organic dye model, the photo‐Fenton catalytic activity of the composite catalyst was significantly higher than that of BiOBr and FeOOH. Among them, 1.8 % FeOOH/BiOBr has the highest photo‐Fenton catalytic activity. The main reason is that the interface effect between FeOOH and BiOBr can enable photogenerated electrons to rapidly transfer from the surface of BiOBr to FeOOH to participate in the Fe3+/Fe2+ cycle. Meanwhile, the quantum size of FeOOH increases the density of active sites on the surface of the composite catalyst. The influence of external factors on the catalytic activity of the catalyst was also verified. Finally, the electron transfer direction and main active species (h+, ⋅O2−) of the composite catalyst were discussed by electrochemical analysis and radical trapping experiments, and a reasonable catalytic degradation mechanism was proposed.

Photo-Fenton degradation of tetracycline antibiotic over MIL-101(Cr)/FeOOH nanocomposite as stable and efficient visible light responsive photocatalyst.

Designing an inexpensive, easily synthesized, stable and efficient photocatalyst is a major challenge in photocatalysis area, especially when photo-reaction is performed in aquatic medium to degrade organic pollutants. To this aim, nano-sized MIL-101(Cr) (MIL = Materials Institute Lavoisier), as chemically tolerant metal-organic framework (MOF), was simply prepared via HF-free hydrothermal synthesis procedure. In order to decorate amorphous FeOOH quantum dots (QDs) on the surface of this MOF, various amounts of FeOOH QDs (i.e., 5, 10, 15 and 20 wt%) were synthesized in the presence of MIL-101(Cr) to prepare MIL-101(Cr)/FeOOH(x%) nanocomposites. Decoration of such iron oxide quantum dots on the surface of MIL-101(Cr) and investigation of its activity in photo-Fenton degradation of tetracycline (TC) antibiotic is reported here for the first time. Among the synthesized nanocomposites, MIL-101(Cr)/FeOOH(15%) demonstrated superior photo-Fenton activity in degradation of TC (80%) at short reaction time under optimum reaction condition using the energy-efficient white LED lamps as visible light source. It was observed that the synergy between any component of this photo-Fenton system such as nanocomposite, hydrogen peroxide and visible light is the main reason for enhancement of TC removal over time. Also, neither MIL-101(Cr) nor FeOOH QDs exhibited poor degradation efficiency, which implies the positive role of the coupling of these materials. Furthermore, the stability and recoverability of MIL-101(Cr)/FeOOH(15%) nanocomposite was investigated in four photo-Fenton cycles, which no significant decrease in TC degradation performance was observed.

Amorphous FeOOH Anchored on Boron and Nitrogen Codoped Carbon Nanotubes for Fenton-like Oxidation of Sulfamethoxazole

Amorphous iron oxide/hydroxides with structural disorder can be a potential alternative to typical crystalline structures when applied in environmental nanotechnology. In this work, novel amorphous FeOOH quantum dots (QDs) anchored on boron and nitrogen codoped graphene nanotubes (FeOOH@BNG) with different Fe loadings were synthesized and applied in the degradation of common antibiotic pollutant sulfamethoxazole (SMX). The as-fabricated catalysts were characterized by a series of physicochemical and thermal techniques, revealing the highly dispersive FeOOH QDs on the BNG surface. The as-prepared catalyst shows excellent catalytic ability toward SMX degradation via a Fenton-like approach. The excellent activity of the as-prepared FeOOH@BNG catalysts was ascribed to the enhanced textural properties and better exposure of active sites, thanks to the highly dispersive Fe sites on the BNG supports. The optimal catalyst, FeOOH-5@BNG, was further employed for the optimization of key reaction parameters such as catalyst loading, H2O2 dosage, pH, and reaction temperature. Moreover, electron paramagnetic resonance (EPR) and reactive species quenching tests were employed to reveal the responsive reactive oxygen species and the mechanism in the FeOOH@BNG/H2O2 system for SMX degradation. The current study not only opens new insights into the fabrication of amorphous but metallic nanomaterials but also leads to their potential application in environmental remediation.

An efficient metal oxyhydroxide catalyst for electrocatalytic hydrogen evolution reaction

An enormous amount of research is being carried out in electrocatalysis, notably for hydrogen evolution reactions (HER), because of the growing demand for sustainable and clean energy sources. Electrochemical water splitting, which results in hydrogen gas, is a practical path to a carbon–neutral energy system. It is essential to create efficient, cost-effective electrocatalysts to achieve this. In recent years, FeOOH-based catalysts have emerged as intriguing HER candidates due to their excellent activity, stability, and accessibility. This work investigates FeOOH quantum dots as an electrocatalyst for hydrogen evolution and sheds an insight on their unique properties, manufacturing processes, and catalytic activity. The quantum dots have demonstrated good electrochemical activity due to their increased surface area and noticeably higher active sites. With the use of UV–vis spectroscopy, XRD, TEM, and electrochemical studies of the catalyst activity, the catalyst has been well characterised. The catalyst demonstrated amazing activity, a decreased Tafel slope, and a lower overpotential, making it a potential option for use in the future.

Decoration of NH2-UiO-66 with FeOOH quantum dots for improving photo-degradation of organic dyes upon visible light irradiation

Coupling of inexpensive and easily synthesized FeOOH quantum dots (QDs) with metal–organic frameworks (MOFs) is an outstanding subject in photocatalysis field, which no research works have been reported in this regard so far. For this purpose, a novel photocatalyst was prepared by in-situ formation of different amounts of FeOOH QDs (5, 10 and 15 wt%) in the presence of NH2-UiO-66 as visible light-harvesting MOF. HR-TEM analysis revealed uniform decoration of NH2-UiO-66 with 2–5 nm sized FeOOH QDs. Photo-Fenton behavior of the resulted NH2-UiO-66/FeOOH(10 %) composite in the degradation of methyl violet (MV) was found to be higher than other composites with different loadings of FeOOH QDs. The effect of H2O2 and photocatalyst dosage were also investigated and the best degradation efficiency of 82.2 % was achieved at optimal reaction conditions. It was observed that both FeOOH QDs and NH2-UiO-66 demonstrated poor photocatalytic activity individually, but their composite resulted in outstanding photo-Fenton activity because of effective electron transfer from photo-excited NH2-UiO-66 to FeOOH QDs. Scavenging experiments indicated that hydroxyl radicals and photo-generated hole are the main species responsible for photo-Fenton degradation of water contaminants.

A self-sufficient photo-Fenton system with coupling in-situ production H2O2 of ultrathin porous g-C3N4 nanosheets and amorphous FeOOH quantum dots

Photo-Fenton degradation of pollutants in wastewater involving hydrogen peroxide (H2O2) and Fe2+ ions to produce hydroxyl radicals (·OH) with high oxidative activity is an ideal and feasible choice in advanced oxidation processes (AOPs). However, the photo-Fenton degradation application is limited by the range of acidic pH and the external introduction of H2O2 and Fe2+ ions. Herein, a self-sufficient photo-Fenton system was developed by coupled ultrathin porous g-C3N4 (UPCN) nanosheets that spontaneously produce H2O2 with amorphous FeOOH quantum dots (QDs) via in-situ deposition method for efficient photo-Fenton degradation of oxytetracycline (OTC) under natural pH condition. The enhancement of photocatalytic degradation activity comes from the synergistic effect of amorphous FeOOH QDs and UPCN nanosheets as follows: on the one hand, the formation of photo-Fenton system combining in-situ generation H2O2 of UPCN with amorphous FeOOH QDs can better boost photocatalytic activity for degrading OTC solution in natural pH under light illumination; on the other hand, the ultrathin porous structure of UPCN can better promote the rapid transfer and dispersion of photo-generated electrons from UPCN to amorphous FeOOH QDs and then Fe3+ is reduced to Fe2+ to participate in the Fenton catalytic reaction.

High-performance FeOOH quantum dots: A novel one-pot microemulsion method for fast preparation and adsorption kinetics

As an emerging material, FeOOH quantum dots (QDs) are being used for their applications in the photodegradation of organic pollutants. However, as a promising adsorbent for the removal of dyes from aqueous solution, their adsorption performance has not yet been studied, and the fabrication of FeOOH QDs typically involves a time-consuming process. To improve its preparation efficiency, a one-pot microemulsion method for the fast fabrication of FeOOH quantum dots was successfully developed, by which FeOOH QDs of approximately 5 nm were successfully prepared within 30 min. The as-synthesized FeOOH QDs were characterized by XRD, XPS, BET, HR-TEM, and AFM. The adsorption properties of the FeOOH QDs for methyl orange (MO) were investigated, and the adsorption mechanism was studied via adsorption kinetics and adsorption isotherms. The results indicated that the adsorption of MO onto FeOOH QDs was a chemisorption process that follows the Langmuir isotherm. The FeOOH QDs possess a high BET surface area of 97.24 m2/g and can achieve a maximum adsorption capacity (qm) of 167.22 mg/g for MO, as estimated by the Langmuir isotherm. The adsorption performance of FeOOH QDs is better in acidic solution than it is in basic solution, and the FeOOH QDs show good stability and reusability.

FeOOH quantum dot decorated flower-like WO3 microspheres for visible light driven photo-Fenton degradation of methylene blue and acid red-18

In this study, nano-flower WO3 hollow microspheres were synthesized by calcining SrWO4 precursors at 300 °C. The WO3-FeOOH-X series photocatalysts were synthesized by successfully anchoring the amorphous FeOOH quantum dots uniformly on the WO3 nanoflower petals. Azo dyes in single system (MB, AR-18) and mixed system (MB+AR-18) were treated synergistically by light and Fenton. The reusability of WO3-FeOOH-3 samples at ambient temperature was investigated. Active species removal experiments were conducted to reveal their photo-Fenton degradation mechanism of organic pollutants. The results showed that the degradation rate of WO3-FeOOH-3 was 98.69% for MB within 5 min. The degradation rate of AR-18 was 92.55%. The mixed dye system (MB+AR-18) became clarified within 5 min. The efficient degradation rate was attributed to the homogeneous dispersion centers and the multiple active sites provided by the WO3 petals for FeOOH anchoring. In conclusion, WO3-FeOOH-X provides a new pathway and applicability for the efficient degradation of MB and AR-18 azo dyes.

Operando leaching of pre-incorporated Al and mechanism in transition-metal hybrids on carbon substrates for enhanced charge storage

Operando leaching of pre-incorporated Al and mechanism in transition-metal hybrids on carbon substrates for enhanced charge storage

Amorphous FeOOH quantum dots decorated on g-C3N4 nanosheets for high-performance energy storage electrodes

Quantum dots (QDs) have recently attracted intensive attention for electrode materials due to their tunable physical dimensions, unique surface effect and pseudocapacitive property. Nevertheless, direct employment of QDs as electrode materials are plagued because of their intrinsic aggregation. In this work, we have successfully fabricated amorphous FeOOH QDs and FeOOH/g-C3N4 hybrid nanosheets as electrode materials using a scalable and bottom-up synthesis route. The FeOOH/g-C3N4 composite possesses a unique heterostructure, comprising a highly dispersed FeOOH QDs anchored on g-C3N4 nanosheets. We probe the behavior of as-prepared hybrid sample, which collectively delivers significant improvement in terms of ultrahigh specific capacitance and long-term stability. The FeOOH/g-C3N4-20 electrode exhibits a large specific capacitance of about 270.8 F g−1 at 1 A g −1, prominent rate capability at high scan rates, and favorable capacitance retention (78.3% capacitance retention after 3000 cycles).

Construction of FEOOH/semiconductor nanosheets heterogeneous catalysts for efficient photo-Fenton degradation of tetracycline hydrochloride

The development of effective heterogeneous catalysts for refractory organic pollutants removal is highly desirable. Herein, a series of 0D/2D hybrids with FeOOH quantum dots intimately anchored on the surface of the semiconductor nanosheets were fabricated and used as photo-Fenton catalysts for tetracycline hydrochloride (TCH) degradation. The optimized FeOOH/BOBC-2 hybrids exhibited superior TCH removal efficiency than that of pure BOBC-2 and FeOOH, which was 2.14 and 2.08 times higher than BOBC-2 and FeOOH. In addition, the influential factors, including the dosage of the catalyst, initial concentration of the TCH, the amount of H2O2 and initial pH were investigated. Detailed characterizations suggest that the enhanced specific surface areas and the effective separation of the photoinduced charge carriers make great contributions to the improvement of the photo-Fenton performance. Meanwhile, the effective charge mobility could promote the conversion between Fe3+ and Fe2+, boosting the activation of H2O2. It is expected this work could provide a common strategy for the fabrication of effective catalyst for environmental remediation.

Low-Temperature synthesis of FeOOH Quantum Dots as Promising Electron-Transporting Layers for High-Performance Planar Perovskite Solar Cells

The development of a low-temperature processed electron-transporting layers (ETL) is highly desirable for high-performance planar perovskite solar cells (PSCs) toward large-scale and flexible devices, yet remains a great challenge. Herein, a low-temperature route was applied to synthesize FeOOH quantum dots (QDs) as promsing ETL for PSCs. A systematic survey of the structure, morphology and band structure was carried out, and the device performance further illustrates that the device based on FeOOH QDs ETL achieves a high efficiency of 17.3% with negligible hysteresis. Moreover, a stable current output at 0.8 V in 400 s was observed in the champion device. As a result, the low-temperature preparation of FeOOH QDs ETL and the corresponding excellent performance of PSCs present great commercial potential for future applications.

Pseudocapacitive quantum dots confined in sacrificial g-C3N4 derived carbon nanosheets for high performance ionic liquid-based supercapacitors

Assembling supercapacitors (SCs) using high-voltage ionic liquid (IL) as electrolyte is an effective strategy to enhance the energy density of SCs. Herein, a novel pseudocapacitive quantum dots (QDs)-based electrode with superior electrochemical behaviors in IL electrolyte has been put forward. Remarkably, FeOOH QDs (FQDs) are effectively confined in a two-dimensional (2D) nanospace supported by porous N-doped carbon (PNC) derived from graphitic carbon nitride (g-C3N4). Beneficial from the abundant active sites and high surface wettability, the resultant FQDs/PNC electrode exhibits sufficient redox reaction and favorable electrochemical kinetics in IL electrolyte. As a result, it can deliver a large specific capacitance of 210.6 F g−1 and still retain 82.2% of its initial capacitance after 10,000 cycles.

FeOOH quantum dots decorated graphene sheet: An efficient electrocatalyst for ambient N2 reduction

Electrochemical N2 reduction offers a promising alternative to the Haber-Bosch process for sustainable NH3 synthesis at ambient conditions, but it needs efficient catalysts for the N2 reduction reaction (NRR). Here, we report that FeOOH quantum dots decorated graphene sheet acts as a superior catalyst toward enhanced electrocatalytic N2 reduction to NH3 under ambient conditions. In 0.1 M LiClO4, this hybrid attains a large NH3 yield rate and a high Faradaic efficiency of 27.3 µg·h−1·mg−1cat. and 14.6% at −0.4 V vs. reversible hydrogen electrode, respectively, rivalling the current efficiency of all Fe-based NRR electrocatalysts in aqueous media. It also shows strong durability during the electrolytic process.

Porous g-C3N4 and MXene Dual-Confined FeOOH Quantum Dots for Superior Energy Storage in an Ionic Liquid.

Owing to their unique nanosize effect and surface effect, pseudocapacitive quantum dots (QDs) hold considerable potential for high‐efficiency supercapacitors (SCs). However, their pseudocapacitive behavior is exploited in aqueous electrolytes with narrow potential windows, thereby leading to a low energy density of the SCs. Here, a film electrode based on dual‐confined FeOOH QDs (FQDs) with superior pseudocapacitive behavior in a high‐voltage ionic liquid (IL) electrolyte is put forward. In such a film electrode, FQDs are steadily dual‐confined in a 2D heterogeneous nanospace supported by graphite carbon nitride (g‐C3N4) and Ti‐MXene (Ti3C2). Probing of potential‐driven ion accumulation elucidates that strong adsorption occurs between the IL cation and the electrode surface with abundant active sites, providing sufficient redox reaction of FQDs in the film electrode. Furthermore, porous g‐C3N4 and conductive Ti3C2 act as ion‐accessible channels and charge‐transfer pathways, respectively, endowing the FQDs‐based film electrode with favorable electrochemical kinetics in the IL electrolyte. A high‐voltage flexible SC (FSC) based on an ionogel electrolyte is fabricated, exhibiting a high energy density (77.12 mWh cm−3), a high power density, a remarkable rate capability, and long‐term durability. Such an FSC can also be charged by harvesting sustainable energy and can effectively power various wearable and portable electronics.

Highly efficient visible-light-driven photo-Fenton catalytic performance over FeOOH/Bi2WO6 composite for organic pollutant degradation

Amorphous FeOOH quantum dots (QDs)-decorated Bi2WO6 nanosheet heterostructures (FeOOH/Bi2WO6) were successfully fabricated through a combined hydrothermal and impregnation approach, characterized by many modern techniques, and employed as an efficient visible-light-driven photo-Fenton catalyst for the degradation of organic pollutants including methylene blue, rhodamine B and tetracycline hydrochloride. The results showed that the photo-Fenton catalytic performance of FeOOH/Bi2WO6 composite is much higher than those of single FeOOH QDs, Bi2WO6 and their physical mixture. Especially, 0.9% FeOOH/Bi2WO6 composite indicated a highest photo-Fenton catalytic activity. This can be attributed to that the synergistic effects of FeOOH and Bi2WO6 can promote the rapid transfer of photo-generated electrons from Bi2WO6 to FeOOH QDs and accelerate the reduction of Fe (III) to Fe (II) by photo-generated electrons and the conversion of dissolved oxygen in water into the strong oxidant superoxide negative radicals (·O2−). The presence of hydrogen peroxide (H2O2) enables the oxidation of Fe (II) to Fe (III) and the formation of a great number of additional hydroxyl radicals (·OH). These active radicals ·OH and ·O2− confirmed by electron spinning resonance spectra greatly improved the degradation of organic pollutants. In addition, the dosage effect (catalyst, H2O2) and acidity-basicity effect were investigated and a reasonable mechanism of pollutant degradation was proposed. Finally, the superior stability and reusability of catalyst were confirmed by five-recycled use for a promising candidate for water remediation in industrial application.