Redox Capability Research Articles

Designing flexible TiO2/SrTiO3/BiOBr recyclable fiber membrane with spatial dual oxidation sites for photocatalytic uranium extraction under visible light

The utilization of nuclear energy generates a substantial volume of wastewater containing uranium, posing a significant threat to both aquatic ecosystems and human health. The current photocatalytic materials utilized for uranium extraction commonly exhibit insufficient redox capabilities, inefficient separation of photogenerated carriers, and challenging recovery. Therefore, recyclable TiO2/SrTiO3/BiOBr (TSB) dual Z-scheme heterojunction fiber membrane materials with dual oxidation sites were successfully synthesized, with advantages of rapid carrier separation and transfer and a broad photo-response range of the dual Z-scheme heterojunctions. Due to the presence of dual oxidation sites, TSB exhibited an exceptional uranium extraction performance, achieving a remarkable 98.9 % extraction rate without the need for sacrificial agents, which was 2.48, 1.79, and 3.34 times of those of ordinary TiO2, SrTiO3, and BiOBr, respectively. The extraction rate of uranium from TSB was 85 % after five cycles. Optical and photoelectric tests revealed that TSB reduced the bandgap width by 0.25 eV compared to that of TiO2, enhanced the fluorescence lifetime by 1.3 ns, lowered the electrical resistance, and higher optical current density, confirming the effective charge transport at the catalyst interfaces. The charge transfer routes in the TSB dual Z-scheme were confirmed by X-ray photoelectron spectroscopy and density functional theory. The potent oxidizing ·OH generated by TSB played a crucial role in facilitating the conversion of U(VI) into insoluble (UO2)O2·2H2O. In conclusion, this work provides a novel strategy for the design of dual Z-scheme heterojunctions and offers a new method for practical and recoverable uranium extraction.

G-C3N4 based Z-scheme photocatalysts for tetracycline degradation: A Comprehensive Review

Graphitic carbon nitride (g-C3N4) has garnered significant attention due to its low cost, ease of preparation, high chemical stability, and non-toxicity. Nevertheless, pristine g-C3N4 faces challenges in simultaneously achieving a broad absorption range, high stability, efficient charge separation, and strong redox capability, which hampers its practical applications. Recently, g-C3N4-based Z-scheme photocatalysts have emerged as research hotspots owing to their robust redox ability, effective charge carrier separation, and capacity to harness visible light for degradation of tetracyclines (TCs) in waters. This review delves into the fundamental photocatalysis, and application of g-C3N4-based Z-scheme photocatalysts for the degradation of TCs pollutants. The review concludes with final remarks and a concise discussion on the prospects of g-C3N4-based Z-scheme photocatalysts.

Fabrication of CdIn2S4/ZnS S-scheme heterojunction via in-situ phase transformation for boosting photocatalytic conversion of organic compounds

Developing efficient photocatalysts is one of green and low cost tactic for addressing the environmental deterioration and energy crisis. Therefore, it remains a fantastic and important strategy to design an efficient junction between different semiconductors for harvesting solar light, boosting the redox capability. Herein, the fabrication of ZnS in situ decorated CdIn2S4 (referred to as CIS-Zx) were prepared by converting ZnS particles on Cd2In4S surface by a facile cation exchange method during solvothermal synthesis. According to a series of PEC measurements and DFT calculations, the bending of band edge as well as the establishing of built-in electric field in the interface of CIS/ZnS heterojunction were concluded, causing the formation of in-situ S-scheme heterojunctions in CdIn2S4/ZnS. The in-situ S-scheme heterojunctions can effectively ameliorate the migration behaviors of photo-generated charges. Compared with pure CdInS4, ZnS and physically mixed CdIn2S4/ZnS, the CIS-Zxin-situ S-scheme heterojunction exhibits efficient photocatalytic activity and stability in the selective reduction of aromatic nitro compounds and oxidation of aromatic alcohols, it is hoped that this work will open up a new avenue for innovative applications of in-situ S-scheme heterojunctions.

Reactive oxygen species-responsive coating based on Ebselen: Antioxidation, pro-endothelialization and anti-hyperplasia for surface modification of cardiovascular stent

Atherosclerosis is often accompanied by inflammation and oxidative stress. Excessive reactive oxygen species (ROS) can damage the vascular endothelium, leading to endothelial dysfunction and reduced nitric oxide (NO) bioavailability. Further accumulation of ROS contributes to vascular cell damage, lipid peroxidation, and extracellular matrix deposition. Thus, clearing excess ROS and reshaping the oxidative microenvironment is essential for treating atherosclerosis (AS). In this study, Ebselen, which mimics glutathione peroxidase and possesses redox capabilities, was successfully synthesized. Subsequently, a multifunctional coating was designed using a combination of Ebselen and poly (trimethylene carbonate) (PTMC), capable of protecting cells from ROS-induced damage, promoting vascular endothelialization, and exhibiting anti-proliferative properties. The Ebselen-loaded coating effectively scavenges free radicals (with an elimination rate of 89 %), catalytically releases NO (0.96 × 10⁻¹⁰ to 1.26 × 10⁻¹⁰ mol/cm²/min), and sustainably delivers Ebselen to the lesion site through a redox cycle. Notably, this coating shows excellent hemocompatibility and cytocompatibility. Subcutaneous implantation results indicated that the fibrous capsule thickness of PTMC10 was the lowest, at just 47.7 % of that of PTMC. Therefore, the Ebselen-loaded coating presents promising applications in cardiovascular stents.

Elaborate construction of a MOF-derived novel morphology Z-scheme ZnO/ZnCdS heterojunction for enhancing photocatalytic H2 evolution and tetracycline degradation

Elaborate construction of novel Z-scheme heterojunction with exceptional morphology derived from metal-organic framework (MOF) have been attracted greatly interest for improving the photocatalytic ability. Herein, a Z-scheme ZnO/ZnCdS heterojunction of rare morphology with ultrathin-nanosheet assembled hierarchical morphology ZnCdS supporting on rich gap ZnO nanospheres were constructed from Zn-based MOF (namely PZH-139) for the first time. This unique feature increased specific surface area, offered abundant mass transport channels and accessible catalytic active sites, accelerated electron migration, which highly elevated photocatalytic property. Furthermore, electron paramagnetic resonance (EPR) measurements and density functional theory (DFT) calculations confirmed the reservation of strong redox capability owing to Z-scheme electron transfer path and the ΔGH* closer to zero of Z-scheme ZnO/ZnCdS system were another two key factors for boosting the photocatalytic activity. As a result, 3-ZnO-700/ZnCdS-160 with optimal morphology showed the best H2 generation performance of 15.43 mmol h−1 g−1 and degradation tetracycline (TC) efficiency of 98.14 %. This work offered a novel and feasible idea for elaborate synthesis of the high-efficiency Z-scheme ZnO/ZnCdS heterojunction with special morphology derived from Zn-MOF.

Laser-engraved defects in TiO2 support: Enhancing reducibility and redox capability of Pt/TiO2 catalyst for reactive and selective hydrogenation

Titanium dioxide (TiO2) has been studied as catalyst or catalyst support in catalysis. Its synthesis or modification approach controls the structural, optical, and electronic properties. Here we applied laser engraving to the anatase TiO2 and studied the consequent changes in its structure and property as well as the properties of TiO2 supported platinum (i.e., Pt/TiO2) catalyst. The laser engraving enlarged the particle size, formed rutile phase and created defects (i.e., oxygen vacancy (Ov) and Ti3+) in anatase TiO2. This induced band gap change and enhanced visible light absorption. The defects created by laser engraving are stable and more reducible than those existed in the pristine TiO2. The defective TiO2 is structurally stable and has great redox properties. The metal-support interaction in the Pt/defective TiO2 catalyst is stronger than that of the pristine Pt/TiO2 catalyst, which enabled higher reactivity and selectivity in hydrogenation of 3-nitrostyrene and furfuryl alcohol. Laser-engraved TiO2 has been rarely studied for thermal catalysis. This work provides basic understanding of material properties and catalysis application of laser-engraved catalyst supports and catalysts in field of thermal catalysis.

Novel framework-confined Cu@ 13X catalyst with excellent resistance to toxic SO2 as an eco-friendly substitute for hazardous V-based NH3-SCR catalyst

V2O5-WO3/TiO2 (VWTi) catalyst has long been utilized in fixed source flue gases to purify harmful NO gas. However, VWTi is classified as a hazardous material because of its harm to human health and environment. To address this issue, a low-cost green Cu-based zeolite catalyst (Cu@13X) with a wide temperature range was synthesized using an in-situ hydrothermal method. This method is intended to control the adsorption capacity of toxic SO2 by regulating the location of Cu species. UV-Vis DRS and EXAFS analyses revealed that a significant amount of Cu was encapsulated within the 12-membered ring pores of the 13X molecular sieve. SO2-TPD and DFT calculations further indicated that Cu@ 13X exhibits reduced SO2 chemical adsorption capacity. Consequently, this green catalyst demonstrated superior catalytic performance, maintaining superior NOx conversion for over 70 h in the mixture gas containing 250 ppm SO2; while the Cu/13X catalyst lacked NH3-SCR catalytic activity under the same conditions. Moreover, Cu@ 13X catalyst also has excellent NH3-SCR catalytic performance in low temperature flue gas below 250 °C, which is significantly better than the hazardous VWTi catalyst. Characterization techniques such as NH3-TPD, H2-TPR, and XPS confirmed that the Cu@ 13X catalyst possesses excellent acidity, robust redox capabilities, and abundant surface defects. In-situ DRIFT spectra further illustrated that the NH3-SCR reaction on the catalyst surface adheres to the Eley-Rideal mechanism both before and after the introduction of toxic SO2. This study offers a fresh perspective on the development of framework-confined NH3-SCR catalysts and elucidates the mechanism behind the sulfur resistance of these catalysts. And the green Cu@ 13X catalyst is anticipated to serve as an effective alternative to the hazardous VWTi catalyst.

Solid-Solution MXenes: Synthesis, Properties, and Applications.

ConspectusMXenes, among other two-dimensional (2D) materials such as graphene, hexagonal BN, transition metal dichalcogenides (TMDs), 2D metal-organic frameworks (MOFs), and covalent organic frameworks (COFs), are the fastest growing class discovered thus far. The general formula of MXenes is Mn+1XnTx, where M, X, and Tx represent an early transition metal (Ti, V, Nb, Mo, etc.), C and/or N, and the surface functional groups (typically, O, OH, F, Cl), respectively, and n can be between 1 and 4. MXenes as a class of materials have extraordinary properties, such as high electrical conductivity, nonlinear optical properties, solution processability, scalability and ease of synthesis, redox capability, and tunable surface properties, among others; the specific properties, however, depend on their chemistry. Since the initial report of the first MXene in 2011, the research community has primarily focused on Ti3C2Tx, and the amount of research work to investigate its synthesis and properties has increased exponentially over the years. In materials science, alloying is a useful way of synthesizing new materials to improve the properties of a class of materials. Advancement of steel and synthesis of inorganic semiconductors can be regarded as some of the major historical advancements in the concept of alloying. Thus, just one year after the initial report of MXenes, the first solid-solution MXene, (TiNb)2CTx, was reported, which demonstrates the inherent chemical tunability of this class of materials.MXenes have two sites for compositional variation: elemental substitution on both the metal (M) and carbon/nitrogen (X) sites, presenting promising routes for tailoring their properties. X-site solid-solutions include carbonitride MXenes and are the least studied class of MXenes to date. Comparatively, multi-M MXenes have acquired significant attention, leading to the extreme example of high-entropy solid-solution MXenes. By using multiple M elements, a significant expansion of the structural and chemical diversity is possible, giving rise to novel chemical, magnetic, electronic, and optical properties that cannot be accessed by single-M MXenes. Solid-solution MXenes represent the largest and most tunable class of MXenes; solid-solution MXenes are those that have multiple metals that are randomly distributed on their M sites with no distinct chemical ordering. Using multiple M elements in MXenes, it is possible to synthesize novel MXene structures that cannot be produced otherwise, such as M5X4Tx MXenes. Based on their chemistry, it is possible to rationally control the electronic, optical, mechanical, and chemical properties in a way that no other class of MXenes can. In some cases, the resultant property is linearly related to the chemistry, such as the electrical conductivity, while in other cases the properties are nonlinear or emergent: optical properties, enabling these MXenes to fulfill roles that no other MXene, or 2D material, can.In this Account, we discuss the recent progress in the synthesis, properties, applications, and outlook of solid-solution MXenes. Importantly, we demonstrate how multi-M solid-solutions can be used to tailor properties for specific applications easily.

Effective abatement of naphthalene from flue gas by V-W/Ti catalyst: Study of vanadium species and reaction mechanism

The removal of naphthalene is important but deficient, so that the available V-W/Ti catalysts (1.0 wt% V2O5/TiO2) were prepared for its efficient abatement in this work. Especially, influences of different existence status of vanadium species on naphthalene elimination were investigated via changing the pH value of precursor solution. With the increase of precursor solution acidity, more highly polymeric vanadium species were formed on the catalyst surface. The redox capability was enhanced markedly as a consequence of the stronger electron transfer between V/W and Ti that induced more surface active oxygen and V5+, whereas the catalytic activity was obviously boosted and almost 90 % conversion of naphthalene was achieved at 293 °C. Moreover, the weaker chemisorption between naphthalene and V-W/Ti catalyst allowed the deeper conversion to COx. GC–MS manifested that naphthalene seemed to be an organic component that was difficult to be totally degraded. Naphthalene oxidation was in the following pathway of naphthalene → 1,4-naphthoquinone → phthalic anhydride → phthalates → benzene → benzoquinone → maleic anhydride → COx/H2O. The opening of aromatic ring in phthalic anhydride and benzene ring in benzene were proven to be the rate-controlling step based on in-situ DRIFTS results. The key of naphthalene oxidation was the complete degradation of various intermediates.

Z-scheme InVO4/ZnFe2O4 heterojunction for efficient photocatalytic nitrogen fixation

Given outstanding light absorption and utilization capabilities, narrow-bandgap semiconductors receive intensive interests in the photocatalysis field. However, the narrow bandgap is a double-edged sword, with the non-negligible charge carrier recombination and hinderance of redox reactions due to the limited redox capability. The construction of Z-scheme heterojunctions could address the aforementioned issues. In this work, we selected two band-matched narrow-bandgap semiconductor catalysts (InVO4 and ZnFe2O4) for the construction of a Z-scheme heterojunction. Compared with pure InVO4 and pure ZnFe2O4, the as-obtained InVO4/ZnFe2O4 Z-scheme heterojunction exhibited improved light harvesting capability and enhanced photogenerated electron-hole pair separation rate. The regulated energy band structure of as-formed InVO4/ZnFe2O4 Z-scheme heterojunction could accelerate the spatial separation of photogenerated electrons and holes, reduce the recombination probability, and provide sufficient electrons to participate in the nitrogen reduction, ultimately significantly promoting photocatalytic activity. Benefiting from above improvements, the NH3 yield of InVO4/ZnFe2O4 for photocatalytic nitrogen fixation was up to 453.37 μmol/gcat/h, which was about 17.7 times and 62.9 times higher than that of pure InVO4 and ZnFe2O4 samples, respectively. This study gives a promising guidance to the facile design and utilization of Z-scheme heterojunction composed of narrow-bandgap semiconductors.

Highly efficient adsorption and visible-LEDs-driven photodegradation of tetracycline over novel and green-synthesized p-BiOI/n-Bi2WO6 heterojunctions

Preparing bismuth compounds-based heterojunctions with superior redox capability has emerged as a promising strategy for environmental remediation. Herein, p-BiOI/n-Bi2WO6 heterojunctions were successfully obtained via a novel, facile, and green solvothermal method. The heterojunctions were synthesized using different mass ratios (1:2, 1:1, and 2:1) of BiOI (BI) and Bi2WO6 (BW), with 1:1 as the best ratio, which was decorated with silver nanoparticles (Ag-NPs) and nitrogen-doped graphene (NG) applying green methodologies. The as-prepared BI/BW heterojunctions were characterized by several techniques, and their adsorption capacity and photodegradation activity toward tetracycline (TC) under 19 W visible LEDs illumination were investigated. The capacity of pure BI, BW and BI/BW heterojunctions for adsorbing TC ranged from 14 to 68 mg/g; among the heterojunctions, Ag/1BI/1BW showed the highest TC adsorption capacity, 35 mg/g. Moreover, the photocatalytic tests revealed that the Ag/1BI/1BW exhibited the highest catalytic performance, achieving a TC percentage degradation of 81 % within 120 min. The low nominal power consumption of the LED-based photoreactor (0.0475 kWh) was significantly lower than that reported in the literature for using Xe or Hg lamps. In addition, catalyst dosage, initial TC concentration, and solution pH were investigated, demonstrating that they play important role in TC photodegradation. Scavenger assays determined that the degradation of TC using Ag/1BI/1BW proceeds mainly via superoxide radicals and holes, which agrees with the carrier transfer mechanism postulated for this heterojunction. TOC analysis revealed that the efficiency of Ag/1BI/1BW was 63 %, and reuse tests confirmed its high performance even after three cycles. This research provides new insights into the design of high-performance heterojunctions for water treatment.

Activation of persulfate over double S-scheme photocatalyst fabricated by decoration of Fe2(MoO4)3 and MoO3 on modified g-C3N4 for degradation of pollutants

The development of nanostructured photocatalysts with high activity is essential for the remediation of effluents. Herein, modified g-C3N4 (M-CN) was integrated with Fe2(MoO4)3/MoO3 (FMO/MO) nanoparticles by one-pot hydrothermal route, and employed to activate persulfate (PS) under visible light. The M-CN/FMO/MO nanocomposites exhibited superior performance in photocatalytic removal of three antibiotics, containing amoxicillin (AMX), azithromycin (AZT), and tetracycline (TC), and three dye pollutants, including rhodamine B (RhB), methylene blue (MB), and methyl orange (MO). The activity of M-CN/FMO/MO (20 %)/PS system for the removal of TC was 1.83, 5.86, and 55.0 folds as high as M-CN/FMO/MO (20 %), M-CN, and CN photocatalysts, respectively. The formation of a double S-scheme system enhanced the photocatalytic performance by effectively retaining electrons and holes, which have strong redox capabilities. This configuration significantly minimized charge recombination, thereby promoting efficient charge transfer and migration. Moreover, there was a significant increases in surface area compared to pure components, which provided active sites for pollutants. Eventually, the recycling test and successful growth of wheat seeds exhibited that the M-CN/FMO/MO (20 %)/PS system can be suitable for wastewater treatment. It is hoped that this system with attractive properties could be used as a promising system in wastewater detoxification.

Regulated charge transfer by cascade dual Z-scheme heterojunction of HCdS@ZnIn2S4-Cobalt porphyrin for efficient photocatalytic solar fuel production

Dual Z-schemed photocatalysts possess superior charge-separation efficiency and powerful redox capabilities, which have attracted significant attention in photocatalytic CO2 reduction (PCR). However, most of the dual Z-scheme systems are focused on inorganic semiconductors, which remain a challenge to control the selectivity of PCR products. Herein, we designed a cascade dual Z-scheme structured organic/inorganic heterojunction of HCdS@ZnIn2S4-Cobalt porphyrin (HCdS@ZIS-CoTPPS). HCdS@ZIS-CoTPPS demonstrated excellent PCR activity (CO rate: 93.64 μmol·g−1·h−1) and adjustable syngas ratio when compared to HCdS, ZIS, CoTPPS, and HCdS/ZIS. Experimental characterizations and density functional theory (DFT) calculations reveal that the superior PCR activity of HCdS@ZIS-CoTPPS is contributed by the broad light absorption range, short charge carrier migration path, low interface contact resistance, and strong redox ability induced by the hollow structured cascade dual Z-scheme heterojunction. This article provides valuable inspiration for the design and preparation of atomistic heterojunctions for solar-driven fuel generation.

Construction of an S-scheme heterojunction with ultra-fast charge transfer at the BP/MOF-808 interface for efficient visible light degradation of metronidazole in the environment

Emerging S-scheme heterojunctions provide catalysts with superior electron transfer pathways and strong redox capacities. Constructing S-scheme heterojunction with two-dimensional nanosemiconductors (with very narrow bandgaps) as interfaces to activate the redox capacity of organic semiconductors (with wide bandgaps) represents a novel method for achieving efficient visible-light photocatalytic degradation of antibiotics. In this study, a BP/MOF-808 S-scheme heterojunction was synthesized through an hydrothermal method. Under visible light excitation (λ = 460 nm), it was demonstrated that photogenerated electrons are transferred from MOF-808 to BP, thereby retaining strong redox capability within the catalytic system. The 3-BP/MOF-808 (300 mg BP) heterojunction exhibited optimal photocatalytic activity, approximately 27.77 times and 27.34 times higher than those of BP and MOF-808, respectively. The results of this work are expected to guide the design and transformation of S-scheme photocatalysts for efficient environmental degradation of antibiotics.

Interface engineering of AgI/(P, K)-g-C3N4 novel S-scheme heterostructures as a highly efficient photocatalyst for RhB degradation

In this study, we developed an in-situ deposition method to load small-sized AgI nanoparticles as an oxidative photocatalyst (OP) onto phosphorus (P) and potassium (K) co-doped two-dimensional porous g-C3N4 (PK-CN-N) as a reductive photocatalyst (RP), forming an S-scheme heterojunction photocatalyst AgI/PK-CN-N. PK-CN-N achieved morphology control and element doping, leading to surface functionalization and heterostructure formation for the AgI/PK-CN-N photocatalyst. Notably, the 50AgI/PK-CN-N composite demonstrated an approximately 95 % removal efficiency for RhB within 30 minutes, 17.6 times higher than pure g-C3N4, surpassing most reported g-C3N4-based photocatalysts. The enhanced photocatalytic efficiency is attributed to the surface modification strategy and heterostructure formation of g-C3N4, which broadens the visible light response range, increases the number of active sites, improves the separation of photogenerated electron-hole pairs, and enhances REDOX capabilities. The band structure of the composite was elucidated through Mott-Schottky analysis and UV–vis DRS. The formation of the AgI/PK-CN-N S-scheme heterojunction and its charge transfer mechanism was confirmed through XPS, band structure analysis, KPFM, and EPR spectroscopy. Experimental data confirmed the presence of a strong and effective interface electric field between the two semiconductors, leading to band bending and accelerated charge separation. Additionally, the introduction of small-sized AgI semiconductors enhanced the exposure of the coupling interface, further improving catalytic performance. The reusability and lifespan of the catalyst were also analyzed, showing that after four cycles, the photocatalytic activity remained above 92 %.

Constructing S-scheme heterojunction Cs3Bi2Br9/BiOBr via in-situ partial conversion to boost photocatalytic N2 fixation

The judicious construction of interfaces with swift charge communication to enhance the utilization efficiency of photogenerated carriers is a viable strategy for boosting the photocatalytic performance of heterojunctions. Herein, an in-situ partial conversion strategy is reported for decorating lead-free halide perovskite Cs3Bi2Br9 nanocrystals onto BiOBr hollow nanotube, resulting in the formation of an S-scheme heterojunction Cs3Bi2Br9/BiOBr. This unique in-situ growth approach imparts a closely contacted interface to the Cs3Bi2Br9/BiOBr heterojunction, facilitating interfacial electron transfer and spatial charge separation compared to a counterpart (Cs3Bi2Br9:BiOBr) fabricated via traditional electrostatic self-assembly. Additionally, the establishment of an S-scheme charge transfer pathway preserves the robust redox capability of photogenerated carriers. Furthermore, the free electron transfer from Cs3Bi2Br9 to BiOBr promotes the activation of the NN bond and diminishes the energy barrier associated with the rate-determining step in the N2 reduction process. Consequently, the Cs3Bi2Br9/BiOBr heterojunction exhibits highly selective photocatalytic N2 reduction to NH3 (nearly 100 %) at a rate of 130 μmol g−1 h−1 under simulated sunlight (100 mW cm−2), surpassing BiOBr, Cs3Bi2Br9, and Cs3Bi2Br9:BiOBr by factors of 6, 4, and 2, respectively.

Enhanced nanocellulose extraction from date palm waste: green solvent hydrolysis with transition metal complex

This study presents a novel method for nanocellulose production using [Bmim]Cl as a green solvent, with enhanced hydrolysis efficiency achieved through the addition of a transition metal complex as a catalyst. The redox capability of the transition metal complex to break the glycosidic bonds in cellulose is amplified by the addition of an oxidizing agent. This protocol represents the latest innovation in the field of nanocellulose production, resulting in improved yield and reduced particle size. Nanocellulose (NC) was extracted from date seeds using 1-butyl-3-methylimidazolium chloride [Bmim]Cl coupled with a transition metal complex comprising copper metal and pyridine as a ligand along with H2O2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{H}}_{2}{\ ext{O}}_{2}$$\\end{document} as an oxidizing agent. Unlike conventional [Bmim]Cl hydrolysis, which typically yields only microcrystalline cellulose (MCC), this approach resulted in a 25% higher yield of NC than that of MCC. Dynamic light scattering analysis showed a substantial reduction in hydrodiameter from 1200 nm for MCC to 128.7 nm for NC, highlighting the remarkable efficiency of this process. Thermal analysis demonstrated the high stability of NC, which showed a Tonset\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${T}_{onset}$$\\end{document} of 286 °C and an activation energy (Ea\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${E}_{a}$$\\end{document}) of 220.41 kJ/mol. X-ray diffraction analysis indicated that NC possessed a high degree of crystallinity (Crl=\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${C}_{rl}=$$\\end{document} 70.28%). Furthermore, NC underwent modification with 3-aminopropyltriethoxysilane to replace free hydroxyl groups (–OH), making it redispersal and suitable for various applications. This modification was confirmed through Fourier transform infrared spectroscopy, which showed the presence of characteristic functional groups, and energy-dispersive X-ray spectroscopy, which verified the elemental composition. Zeta potential measurements revealed surface charge differences, with MCC at − 27.87 mV, NC at − 27.28 mV, and modified NC at − 44.72 mV, indicating improved colloidal stability after modification. These findings highlight the protocol's effectiveness and its potential impact on the NC production industry, offering improved yields and the production of nanosized fibers using green solvents.

Advancing anaerobic digestion with MnO2-modified biochar: Insights into performance and mechanisms

The use of bio-based composites to enhance the methane production in anaerobic digestion has attracted considerable attention. Nevertheless, the study of electron transfer mechanisms and the applications of biochar/MnO2 (MBC) in complex systems remains largely unexplored. Biochar composited with MnO2 at 10:1 mass ratio (MBC10) increased the content of volatile fatty acids by 9.09 % during acidogenic phase. During the methanogenic experiments using acetate, cumulative methane production (CMP) rose by 5.83 %, and in the methanogenic experiments using food waste, CMP increased by 24.32 %. Microbial community analysis indicated an enrichment of Syntrophomonas, Bacilli, and Methanosaetaceae in the MBC10 group. This enrichment occurred mainly due to the redox capability of MnO2 enhancing MBC capacitance, thereby facilitating microbial electron transfer processes. Additionally, under 2 g/L ammonia nitrogen concentration and 30 g/L organic load, the CMP of MBC10 increased by 12.74 % and 9.44 %, respectively, compared to the BC600 group. This study illuminates MBC's electron transfer mechanisms and applications, facilitating its wider practical adoption and fostering future innovations.

Ag doped TiO2 anchored on metal free g-C3N4 for enhanced solar light activated photodegradation of a dye

Heterogeneous semiconductor photocatalysis has attracted researcher's attention in wastewater treatment owing to the improved surface area, optical properties, and charge transfer rate for boosted degradation of organic pollutants. Thus, the g-C3N4/Ag/TiO2 was prepared following a hydrothermal route for the degradation of azo dye tartrazine (TA) used as a food colourant under solar light. Before application, the composite and pristine materials were interrogated for physicochemical and structural properties using SEM, TEM, EDS, XPS, XRD, UV–vis DRS, PL, BET, Raman, and FTIR spectroscopy. The PL and electrochemical analysis revealed that the CNAT composite had a high charge transfer rate that was coupled with low charge carrier complexation. The degradation efficiency of 91 % was realized in 180 min and the rate of pseudo-first-order kinetics of 0.01143 min−1 was obtained. The CNAT catalyst also displayed high removal efficiency towards a cocktail of naproxen (NPX) and TA. The improved removal efficiencies stem from increased visible usage, reduced charge carrier compounding, and formation of Z-scheme heterojunction with high redox capabilities. The total organic carbon removal reached 95 % while CNAT showed high convincing stability even after four cycles. Given the above results, the hydrothermally prepared composite catalyst can be extended to other organic pollutants such as pharmaceuticals, pesticides, and reduction of inorganics.

Coupling monoclinic Pb2(CrO4)O with Mn3O4 quantum dots as oxygen vacancies-rich S-scheme photocatalysts for visible-light-driven photocatalytic CO2 reduction with H2O

Simulating natural photosynthesis to convert CO2 and H2O into fuels achieving overall reaction is a promising solution for addressing environmental problems and energy crises. Constructing an S-scheme catalyst of two or more catalytic sites with rapid electron transfer and strong redox capability may be an effective strategy for coupling photocatalytic CO2 reduction and H2O oxidation. Here, an oxygen vacancies-rich S-scheme semiconductor photocatalyst composed of monoclinic lead chromate oxide (Pb2(CrO4)O) coupled with Mn3O4 quantum dots (QDs) (Pb2(CrO4)O@Mn3O4QDs) are synthesized and tested for photoconversion of CO2 with H2O under visible light. Through the integration of Pb2(CrO4)O with Mn3O4QDs, the photocatalytic C1-evolution rate on Pb2(CrO4)O@Mn3O4QDs is radically increased by 6.0 and 8.1 times, which is much faster than that of pristine Pb2(CrO4)O and Mn3O4. The origin of the greatly raised activity is revealed by advanced characterizations, and in situ X-ray photoelectron spectroscopy (XPS) confirms the electron transport pathway in Pb2(CrO4)O@Mn3O4QDs with light illumination, unveiling the efficient spatial separation/transfer of charge carriers in oxygen vacancies-rich Pb2(CrO4)O@Mn3O4QDs S-scheme heterojunction. Consequently, powerful photoelectrons and holes accumulate in the Mn3O4 conduction band and Pb2(CrO4)O valence band, respectively, exhibiting prolonged long lifetimes and facilitating their involvement in CO2 photoreduction and H2O photooxidation through altering the interfacial charge dynamics.