Reaction Cycle Research Articles

Thermal and Sono-Aqueous Reforming of Alcohols for Sustainable Hydrogen Production.

Hydrogen is a clean-burning fuel with water as its only by-product, yet its widespread adoption is hampered by logistical challenges. Liquid organic hydrogen carriers, such as alcohols from sustainable sources, can be converted to hydrogen through aqueous-phase reforming (APR), a promising technology that bypasses the energy-intensive vaporization of feedstocks. However, the hydrothermal conditions of APR pose significant challenges to catalyst stability, which is crucial for its industrial deployment. This review focuses on the stability of catalysts in APR, particularly in sustaining hydrogen production over extended durations or multiple reaction cycles. Additionally, we explore the potential of ultrasound-assisted APR, where sonolysis enables hydrogen production without external heating. Although the technological readiness of ultrasound-assisted or -induced APR currently trails behind thermal APR, the development of catalysts optimized for ultrasound use may unlock new possibilities in the efficient hydrogen production from alcohols.

Fuel-Driven Dynamic Combinatorial Peptide Libraries.

Dynamic combinatorial chemistry (DCC) creates libraries of molecules that are constantly interchanging in a dynamic combinatorial library. When a library member self-assembles, it can displace the equilibria, leading to emergent phenomena like its selection or even its replication. However, such dynamic combinatorial libraries typically operate in or close to equilibrium. This work introduces a new dynamic combinatorial chemistry fueled by a catalytic reaction cycle that forms transient, out-of-equilibrium peptide-based macrocycles. The products in this library exist out of equilibrium at the expense of fuel and are thus regulated by kinetics and thermodynamics. By creating a chemically fueled dynamic combinatorial library with the vast structural space of amino acids, we explored the liquid-liquid phase separation behavior of the library members. The study advances DCCs by showing that peptide structures can be engineered to control the dynamic library's behavior. The work paves the way for creating novel, tunable material systems that exhibit emergent behavior reminiscent of biological systems. These findings have implications for the development of new materials and for understanding life's chemistry.

Eversa transform 2.0 immobilized on a hydrophobic support enables the solvent-free almost quantitative esterification of the free fatty acids from soybean oil with neopentylglycol

The performance of Eversa Transform 2.0 (ETL) and lipase from Thermomyces lanuginosus (TLL) was compared in the solvent-free esterification of the free fatty acids (FFAs) from soybean oil with neopentylglycol (NPG) to produce NPG-diesters, which may be used as biolubricants. Enzymes were immobilized by interfacial activation on an octadecyl-coated methacrylate macroporous resin (C18) and compared to commercially immobilized TLL (Lipozyme® TL IM), free ETL and TLL. ETL@C18 surpassed the performance of all tested biocatalysts, reaching up to 98 % of FFAs conversion after 6 h of reaction at 50 °C and using a biocatalyst content of 9 wt% (related to the mass of FFAs). After optimization, the reactor temperature had a higher influence on the production of the NPG-diesters than the biocatalyst content, so that 45 °C and 3 wt% were determined to be the optimal values. Under such conditions, ETL@C18 retained approximately 88 % of its initial conversion into the NPG-diesters even after 10 consecutive reaction cycles. The biolubricant is composed mainly of NPG-diesters (∼91 %) and unreacted NPG (∼9 %), as confirmed by NMR analysis. The NPG-diesters exhibited a higher viscosity index (from 190.84 to 215.86) and oxidative stability (from 0.10 h to 1.34 h) than the starting material. The NPG-diesters biolubricant also exhibited a lower friction coefficient (0.049 against 0.064) and wear scar diameter (139.03 μm against 151.43 μm) than the 20W-50 mineral lubricant.

Enzymatically Cyclic Activated Biosensor Based on a Tetrahedral DNA Framework for Precise Tumor in Situ Molecular Imaging.

The development of stimulus-responsive and amplification-based strategies is crucial for achieving improved spatial specificity and enhanced sensitivity in tumor molecular imaging, addressing challenges such as off-tumor signal leakage and limited biomarker content. Therefore, a cyclically activated enzymatic biosensor based on the modification of an AP site within a tetrahedral framework DNA (AP-tFNA) was rationally developed for tumor cell-specific molecular imaging using the endogenous enzyme apurinic/apyrimidinic endonuclease 1 (APE1) as a target, exhibiting superior spatial specificity and high sensitivity. APE1, which predominantly localizes within the nucleus in normal cells but exhibits cytosolic and nucleus expression in cancer cells, can specifically recognize and cleave the AP site in AP-tFNA, resulting in the separation of the fluorophore and quenching group, thereby inducing a fluorescence signal. Additionally, upon completion of the excision of one AP site in AP-tFNA, APE1 is released, thereby initiating a subsequent cycle of hydrolytic cleavage reactions. The experimental results demonstrated that AP-tFNA enables precise differentiation of tumor cells both in vitro and in vivo. In particular, the AP-tFNA can monitor drug resistance in neuroblastoma cells and classify the risk for neuroblastoma patients at the clinical plasma level.

Improved morphological stability of NiFe2O4 via Sr doping for chemical looping hydrogen production

As a new hydrogen production technology, chemical looping hydrogen production has the advantage of internal CO2 separation. NiFe2O4 is considered as promising oxygen carrier material for chemical looping hydrogen production due to the high oxygen carrying capacity and low cost. However, rapid redox performance fading caused by structure degradation and interface instability in successive redox reactions that led fto poor stability, and seriously limited the practical application of NiFe2O4 in chemical looping hydrogen production. Herein, we reported a method for improving the morphological stability of NiFe2O4 through Sr doping. NiFe2O4 samples containing different SrO contents (2 wt%, 5 wt% and 8 wt%) were prepared by a simple mechanical mixing method. A series of characterization analysis results showed that adding an appropriate amount of Sr could significantly improve the microstructure, increase the oxygen vacancy concentration and inhibit the phase segregation of NiFe2O4. The NiFe-5Sr presented the largest BET surface area (24.63 m2/g) and highest concentration of oxygen vacancies (77.49 %). NiFe-0Sr and NiFe-2Sr experienced severe phase segregation during continuous cyclic reactions, resulting in significant surface sintering and deactivation. During 20 redox cycles, NiFe-5Sr presented the highest hydrogen yield (around 10 mmol/g) and stable surface morphology. The research results indicated that the optimal doping amount for SrO was 5 %.

Highly sensitive β-amyloid1–42 oligomer aptamer-based assay via dual cyclic amplifications of three-way catalytic hairpin assembly and palindrome polymerase reaction

β-amyloid1–42 oligomer (AβO1–42), a neurotoxic protein, is considered the key factor in the progression of Alzheimer's disease (AD). And, high sensitivity detection of AβO1–42 is of considerable importance for the early diagnosis and deterioration prevention of AD. We present here an ultrasensitive fluorescent AβO1–42 detection approach based on aptamer recognition probes and a new dual cyclic signal amplification strategy by combining three-way catalytic hairpin assembly (3W-CHA) with palindromic sequence-based polymerase amplification (PBPA). Once the aptamers bind to target AβO1–42 molecules, ssDNA sequences are released to initiate 3W-CHA between three hairpins to unfold the signal hairpins and to form Y-shaped DNA structures (Y-DNAs). Subsequently, the assistance ssDNAs bind the Y-DNAs to expose the palindromic sequences to yield Y-DNA dimers, which lead to cyclic PBPA reaction with presence of polymerase to further unfold more signal hairpins for yielding considerably magnified fluorescence recovery, enabling sensitive assay of AβO1–42 down to 2.4 pM within a dynamic range of 5 pM∼50 nM. Furthermore, this strategy has been validated for interrogation of low AβO1–42 levels in artificial cerebrospinal fluid (CSF), suggesting its promising potential for application in early diagnosis and prevention of AD.

CuI@MIM-SBA-15 hybrid catalyst in the ultrasound-assisted synthesis of 1,4-disubstituted 1,2,3-triazoles in water

Click chemistry reactions transformed organic synthesis by creating enormous compound libraries connecting almost any chemical entity. The copper-catalyzed alkyne-azide cycloaddition (CuAAC) was the most versatile and efficient and transcended diverse scientific fields such as biology and materials science. Thus, the development of new methodologies based on CuAAC keeps growing. A green approach was envisioned by stabilizing the air and water-sensitive CuI over an ordered mesoporous silica/ionic liquid matrix (MIM-SBA-15). The best catalyst performance was in the water as solvent under ultrasound irradiation, which reached quantitative transformation in a short time. Then, the scope was extended to 24 compounds primarily synthesized with high yields (75–99 %); the methodology tolerated different alkynes and azides with aromatic and alkyl groups. This methodology was also successfully tested in high yields in the multicomponent synthesis of 1,4-disubstituted 1,2,3-triazoles from organic bromides, alkynes, and KN3. The hybrid catalyst recovery and reuse were evaluated along ten reaction cycles; there was no significant loss in activity up to cycle number six (94 % yield).

Synthesis of magnetically separable mixed metal oxide nanocomposite (Cu/CoFe2O4) for Huisgen 1,3-dipolar cycloaddition

A magnetically recoverable mixed metal oxide nanocomposite (Cu/CoFe2O4) was synthesized and employed for the Huisgen 1,3-dipolar cycloaddition reaction. Functionally diverse 1,4-disubstituted-1,2,3-triazoles synthesized from aryl halide, sodium azide and terminal alkyne in ethanol. The physico-chemical study of the catalyst was characterized by XRD, SEM, TEM, EDS, TGA, XPS and VSM. Use of sustainable catalytic system, simple procedure, mild reaction conditions, easy work-up, short reaction times, high product yields and use of a benign solvent are remarkable features of the present protocol. The catalyst nontoxic nature and easy recovery and reusability over several reaction cycles makes this protocol more competent.Graphical

Enhancing rhamnolipid production via immobilized Pseudomonas stutzeri lipase: A comparative study

Rhamnolipids (RLs) are widely studied biosurfactants with significant industrial potential in cosmetics, pharmaceuticals, and bioremediation due to their excellent surface activity, emulsifying properties and bioactive characteristics. However, high production costs impede their mass production. This study investigates the immobilization of Pseudomonas stutzeri lipase (PSL) on various supports to enhance RL synthesis efficiency, focusing on yield and regioselectivity in the enzymatic synthesis of 4-O-lauroylrhamnose by the transesterification of rhamnose with vinyl laurate. Three immobilization methods were compared: covalent binding, adsorption on Celite, and adsorption on hydrophobic supports. The immobilization efficiency varied depending on the method used, with the lowest observed for adsorption on Celite (56 %), followed by covalent immobilization on Sepabeads (EC-EP/S 78 % and EC-EP/L 70 %), and the highest for adsorption on hydrophobic supports (83–97 %, with EC-OD being the best at 97 %). For the enzymatic synthesis of 4-O-lauroylrhamnose, covalent immobilization on Sepabeads™ EC-EP yielded low conversions due to restricted conformational freedom of the enzyme. Celite® 545 adsorption resulted in moderate conversion rates, limited by the electrostatic interactions restricting enzyme activity. The most promising results were obtained with hydrophobic supports, particularly Purolite® ECR8806F, achieving nearly complete conversion and maintaining high regioselectivity at the 4-position of rhamnose in both THF and the green solvent 2-methyltetrahydrofuran (2-MeTHF). The study highlights the critical role of support hydrophobicity and active surface area in the immobilized enzyme performance. PSL immobilized on Purolite® ECR8806F demonstrated significant potential for sustainable RLs production, showing excellent reusability, stability and productivity across multiple reaction cycles. This study presents a significant advancement in RLs production by optimizing PSL immobilization and reaction conditions, facilitating the way for more cost-effective and sustainable industrial applications.

3D Tunnel Copper Tetrathiovanadate Nanocube Cathode Achieving Ultrafast Magnesium Storage Reactions through a Charge Delocalization and Displacement Mechanism.

Rechargeable magnesium batteries are attractive candidates for large-scale energy storage applications because of the low cost and high safety, but the scarcity and inferior performance of the cathode materials are hindering the development. In the present study, a kind of copper tetrathiovanadate (Cu3VS4) cathode is designed and developed with a comprehensive consideration of the chemical and electronic structures. The vanadium and sulfur atoms form chemical bonds with high covalent proportion, facilitating electron delocalization via the vanadium-sulfur bonds. This reduces the interaction with the bivalent magnesium cation and induces the coredox of vanadium and sulfur. The crystal structure of Cu3VS4 has interlaced 3D tunnels for solid-state magnesium cation transport. The Cu3VS4 cathode shows a high capacity of 350 mA h g-1 at 100 mA g-1, an outstanding rate performance of 67 mA h g-1 at 10 A g-1, and stable cycling for 1000 cycles at 5 A g-1 without obvious capacity fading. Prominently, a high areal mass load of 3.5 mg cm-2 could be achieved without obvious rate capability decay, which is quite favorable to pair with the high-capacity magnesium metal anode in practical application. The mechanism investigation and theoretical computation demonstrate that Cu3VS4 undergoes first a magnesium intercalation and then a displacement reaction, during which the crystal structure is maintained, assisting the reaction reversibility and cycling stability. All the copper, vanadium, and sulfur elements experience redox and contribute to the high capacity. Moreover, the weakened interaction with magnesium cations, well-kept 3D cation transport tunnels, and high electronic conductivity result in the superior rate performance and high areal active material loading. The present study develops a high-performance cathode for rechargeable magnesium batteries and reveal the design principle based on both of chemical and electronic structures.

Nanoscale precision welding-enabled quasi-3D conductive carbon blacks for fast-charging and long-lasting secondary batteries

Robust three-dimensional (3D) conductive networks are vital for enhancing the utilization, rate capability, and lifespan of battery electrode materials, which largely relies on the selection and synergy of various conductive additives. As the spatial dimension expands from granular to tubular or lamellar, the conductivity of conductive additives continues to increase, but the cost and dispersion difficulty will sharply rise. This determines that zero-dimensional carbon black (CB) spherical nanoparticles remain the dominant component of current composite conductive additives. Herein, we disclosed a transient high-temperature welding technique that can precisely regulate the “rearrangement-fusion” behavior of carbon atoms at specific temperatures, accurately splicing the CB nanospheres into quasi-3D dendritic aggregates with appropriate spatial extension. This not only enhances the powder conductivity of CBs by 205.1 %, but also improves the processability through reducing the specific surface area. The quasi-3D CBs upgrade their contact mode with active materials from point-to-point to line-to-point, while significantly enhancing the inter-particle connection of active materials. More encouragingly, the modified CBs greatly boost the reaction kinetics, rate and cycling performance of LiFePO4 cathode and SiO@C anode, and derives fast-charging and long-lasting SiO@C//LiFePO4 full battery. Our work provides innovative solutions for upgrading the spatial conductive network within future secondary batteries.

Optimization of the full-load combustion schemes of n-butanol/biodiesel reactivity-controlled compression ignition (RCCI) toward high-efficiency and low-emission engines

Biodiesel and n-butanol, as popular alternative fuels, can be used in advanced reactivity-controlled compression ignition (RCCI) engines for efficient and clean combustion. However, the complex interactions between n-butanol and biodiesel, as well as the best combustion schemes at different loads, remain poorly understood. Given this, the objective of this paper is to identify optimal fuel organizations for n-butanol/biodiesel RCCI engines across different load scenarios by combining engine simulation with a global optimization algorithm, explore the potential synergies of control parameters, and analyze microscopic dual-fuel interactions based on the integrated average reaction path analysis. Results show that the optimal scheme at low load employs almost homogeneous fuel-air mixtures at elevated temperature atmosphere above 390 K, with n-butanol energy share exceeding 96% and optimal biodiesel injection timing between −70 and −50 °CA. Higher n-butanol ratio coupled with increased intake temperature improves engine performance. For mid load, biodiesel injection timing is retarded to −55 to −30 °CA, and biodiesel proportion is increased to introduce reactivity stratification, while maintaining its energy share below 20% to mitigate NOx emissions. Notably, biodiesel density is identified as the primary physical property influencing NOx formation. At high load, a split combustion scheme involving premixing and subsequent diffusion combustion is optimal. The physical effects of n-butanol addition minimally impact the low-temperature ignition of biodiesel, while its chemical effects significantly defer the low-temperature reactivity. The reaction path analysis reveals that n-butanol competes with biodiesel for OH radical consumption, with a large proportion of OH and HO2 consumed in the cyclic reactions of nC4H9OH and nC4H8OH. Adjusting the reactivity stratification affects the reaction state of n-butanol entrained by the biodiesel jets. Higher reactivity gradient intensifies biodiesel reactions to induce the pyrolysis of the involved n-butanol through nC4H8OH => 2C2H4 + OH, therefore resulting in more staged heat release.

Microwave-Assisted Synthesis of CdS-MOF MIL-101 (Fe) Composite: Characterization and Photocatalytic Performance.

The present study outlines the synthesis of cadmium sulfide-metal-organic framework (CdS-MOF) MIL-101 (Fe) heterojunctions achieved via fast microwave-assisted reactions. Thus, different CdS-MOF MIL-101 (Fe) ratios were prepared to study their effectiveness as photocatalysts. These compounds were employed in the photocatalytic degradation of methylene blue (MB) under UV and visible irradiation. Structural, morphological, textural, compositional, and optical properties of the synthesized compounds determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy were utilized to characterize the structural, morphological, textural, compositional, and optical properties. Electrochemical impedance spectroscopy (EIS) was also employed to determine photovoltage and photocurrent densities. The resulting valence band offset (Vfb) and band gap energy values were utilized to construct an energy band scheme. Our research revealed that the CdS-MOF MIL-101 (Fe) heterojunction enhances the efficiency of electron-hole pair separation, thereby mitigating charge carrier recombination effects. Moreover, the type I electronic band structure established an efficient reaction mechanism, effectively suppressing the recombination of photogenerated electron-hole pairs. The photocatalytic system demonstrated exceptional behavior, achieving complete MB removal within 30 min of reaction time and exhibiting outstanding stability and reusability after four reaction cycles. These findings highlight the potential of the synthesized compounds in the field of wastewater treatment for organic pollutants, offering a promising alternative to current environmental issues.

Sulfonated reduced graphene oxide (rGO-SO3H): A green, sustainable and efficient heterogeneous catalyst for synthesis of pyrazole containing 1,4 dihydropyridine derivatives

A simple mild, efficient, expeditious and straightforward synthetic methodology has been established toward furnishing of therapeutically important structurally diverse multi-heterocyclic pyrazole containing substituted 1,4-dihydropyridine (1,4-DHP's) derivatives which might be valuable heterocyclic compound because of the existence of pharmaceutically and medicinally important 1,4-dihydropyridine (1,4-DHP) and pyrazole entities. In this reported synthetic strategy, sulfonated reduce graphene oxide was firstly reported as a highly efficient heterogenous carbo-catalyst for one-pot 4-C synthesis of pyrazole based 1,4-dihydropyridine (DHPs) derivatives. The reported sulfonated reduce graphene oxide (rGO-SO3H) offered mild reaction conditions, structural diversity, high atom economy, operational simplicity, high product conversion, high yield (96%) with wide range of substrates within 15–20 min in ethanol at refluxing temperature. Additionally, experiment results revealed that synthesized carbo-catalyst can be recycled and reused efficiently for at least five reaction cycles. All the synthesized compounds were characterized by IR, HRMS, 1H NMR and 13C NMR, spectroscopic techniques.

Recent Achievements in Heterogeneous Bimetallic Atomically Dispersed Catalysts for Zn-Air Batteries: A Minireview.

Rechargeable Zn-air batteries (ZABs) hold promise as the next-generation energy-storage devices owing to their affordability, environmental friendliness, and safety. However, cathodic catalysts are easily inactivated in prolonged redox potential environments, resulting in inadequate energy efficiency and poor cycle stability. To address these challenges, anodic active sites require multiple-atom combinations, that is, ensembles of metals. Heterogeneous bimetallic atomically dispersed catalysts (HBADCs), consisting of heterogeneous isolated single atoms and atomic pairs, are expected to synergistically boost the cyclic oxygen reduction and evolution reactions of ZABs owing to their tuneable microenvironments. This minireview revisits recent achievements in HBADCs for ZABs. Coordination environment engineering and catalytic substrate structure optimization strategies are summarized to predict the innovation direction for HBADCs in ZAB performance enhancement. These HBADCs are divided into ferrous and nonferrous dual sites with unique microenvironments, including synergistic effects, ion modulation, electronic coupling, and catalytic activity. Finally, conclusions and perspectives relating to future challenges and potential opportunities are provided to optimise the performance of ZABs.

CeO2 enhanced performance of NiFe2O4-CaO for carbon capture and in-situ hydrogenation conversion to CO

NiFe2O4 exhibits excellent redox properties and is widely applied in CaO-NiFe2O4 chemical looping processes. However, rapid sintering of Ni-Fe alloy under reaction conditions limited its industrial applications. The CeO2-NiFe-CaO were synthesized through a physical mixing method with NiFe2O4 as a precursor, and its CO2 capture capacity and in-situ hydrogenation performance were conducted on ICCC-RWGS reaction under different conditions. 20CeO2-NiFe-CaO exhibited a CO yielding of 9.35 mmol/g at 650 °C. During the carbon capture stage, CO2 was adsorbed by CaO, leading to the formation of CaCO3. In the hydrogenation conversion stage, hydroxyl groups were generated on the surface, combining with CaCO3 to produce formate species, further generating H2O and CO. 15CNF-CaO exhibited superior cyclic ICCC-RWGS reaction performance compared to 15NF-CaO, with a CO yield of 1.88 mmol/g after 40 cycles. CeO2 inhibited the sintering of catalytic components, preserving a higher specific surface area and smaller particle size. Furthermore, CeO2 in 15CNF-CaO inhibited carbon deposition and enhanced in-situ hydrogenation performance, exhibiting better CaO regeneration capability and better cyclic stability. These results could provide insight for designing the DFMs for the ICCC-RWGS process.

ReaxFF molecular dynamics study of N-containing PAHs formation in the pyrolysis of C2H4/NH3 mixtures

The reactive force field molecular dynamics (ReaxFF MD) simulations are performed to depict the whole process including fuel pyrolysis, the formation and growth of PAHs/NPAHs and soot formation in the pyrolysis of C2H4 and C2H4/NH3 mixtures. NH3 doping increases the concentration of H radicals through the decomposition of NH3. These H radicals then promote the consumption of C2H4 by participating in H-abstraction reactions. The formation of C-N species (mainly HCN, H2CN, C2N, CH3CN, NCCN, and HC3N) removes the C atoms participating in the formation of PAHs and soot, thus inhibiting the formation of soot. And such inhibitory effect is strengthened with increasing temperature due to the promoted formation of C-N species. Most importantly, the structure, formation and evolution paths of N-containing PAHs (NPAHs) are identified based on the experimental and simulation results for the first time, revealing that N atoms in the NPAHs are almost always present in the carbon chains attached to the aromatic rings while barely enter the rings to form heterocyclic structure. The simulations further reveal that when the temperature is less than 2500 K, the first N-containing aromatic ring is formed through the reaction of phenyl with small C-N species (such as HCN and CN radicals), followed by the increase of new rings primarily via the HACA mechanism. At temperatures greater than 2500 K, the formation and growth of NPAHs are dominated by the continuous attachment of N-containing carbon chains and cyclic polycondensation-cyclization reactions. The identification of new C-N species especially NPAHs would help improve the kinetic mechanisms for ammonia blending combustion.

Highly sensitive detection of DNA methyltransferase1 triggered by methylation protection

Type 2 diabetes is on the rise year by year, and 80 % of patients with type 2 diabetes die from cardiovascular complications. Strict control of blood glucose can significantly reduce the occurrence and development of diabetic microvascular complications, but can not effectively prevent the occurrence of diabetic macrovascular lesions. DNA methyltransferase 1 (DNMT1) plays an important role in developing phenotypic switching and secretion of inflammatory factors in vascular smooth muscle cells(VSMC), leading to the deregulation of vascular function. In this work, a biosensor based on methylation protection was designed. In the presence of the target DNMT 1, the formed methylation sites protect the dsDNA from being digested by the HpaII restriction enzyme. At the same time, a large number of G-quadruplex are produced by the catalyzed hairpin assembly (CHA) reaction cycle, and the peroxidase-like activity of G-tetraplex and hemin is used to continuously catalyze the color change of substrate ABTS, thus realizing dual signal amplification. The binding of magnetic beads to dsDNA effectively reduces the background signal and enables a highly selective and sensitive analysis of the target DNMT 1 in complex biological samples, with a detection limit as low as 0.22 UmL−1, showing a good linear relationship in the range of 0.22–10 UmL−1. A new approach for the study of macrovascular damage is provided in type 2 diabetes.

Surface decoration of Nb2O5 hollow fibers by graphene oxide for enhanced photocatalytic degradation of methylene blue

AbstractThis paper describes the fabrication of ceramic Nb2O5 hollow fibers covered by a thin graphene oxide (GO) layer using the vacuum‐assisted dip‐coating process for the efficient photocatalysis degradation of methylene blue (MB) under UVC light irradiation. Pristine and GO‐coated Nb2O5 hollow fibers were evaluated for photocatalytic degradation at different initial dye concentrations and pH values. A photodegradation of 66.4% of the dye molecules was achieved using the pristine Nb2O5 hollow fibers at 57.4 ± 0.1 mg mL1, initial MB concentration of 10 mg L−1, and pH of 11. Under the same experimental conditions, the GO‐coated Nb2O5 hollow fibers degraded 100% of the MB molecules. Additionally, the GO‐coated Nb2O5 hollow fibers were successfully reused for four reaction cycles and exhibited suitable long‐term stability. Thus, the proposed ceramic Nb2O5 hollow fibers with a surface decorated by a GO layer presented suitable characteristics for use as a photocatalyst in MB degradation.

Sol-gel synthesized flexible Na2Ti6O13–aluminium oxide fibres for photocatalytic degradation of Acid red 1

Sodium titanate (Na2Ti6O13; NTO) was loaded onto aluminium oxide fibres (AFs) using the sol–gel method to synthesize NTO/AF fibres. The surface roughness of NTO/AF-n fibres increased with increasing number of dip-coating cycles (n = 1–3). The Fourier transform infrared spectra and X-ray photoelectron spectroscopy spectra of NTO/AF-n demonstrated the loading of NTO onto AF. The bandgap energies of NTO/AF-1, NTO/AF-2, NTO/AF-3 and NTO were determined to be 3.08, 3.12, 3.38 and 3.45 eV, respectively. The production of hydroxyl radicals by fibres under irradiation decreased in the order of NTO, NTO/AF-1, NTO/AF-2 and NTO/AF-3. NTO/AF-n fibres were designed for convenient separation from water, with NTO/AF-1 exhibiting the highest activity among the NTO/AF-n samples. The photocatalytic degradation efficiencies of NTO/AF-1, NTO/AF-2 and NTO/AF-3 after 30 min of reaction were determined to be 61.4 %, 51.7 % and 44.3 %, respectively. Complete removal of Acid Red 1 from the solution was achieved through a photocatalytic reaction using NTO/AF-n. The activity of NTO/AF-n samples remained stable over five reaction cycles, indicating their application potential for large-scale water treatment.