Facile Process Research Articles

New insights into the mechanism causing the loss of anti-corrosion property of superhydrophobic titanium surfaces

In this paper, we provide new insights into the mechanism causing the loss of anti-corrosion property of superhydrophobic titanium (SHP Ti) during potentiodynamic polarization (PDP) measurements. The water contact angle and sliding angle values of the SHP Ti, produced by a facile two-step process: anodizing and coating, were >160° and 6±2°, respectively. The anodization of Ti resulted in randomly distributed micro-clusters of TiO2-xCly covering the Ti surface homogeneously while the low surface energy organic coatings were inhomogeneous in coverage and specifically distributed over the micro-clusters alone of the anodized titanium surface. The electrochemical impedance (EIS) analysis of the SHP CP-Ti samples has shown more than an order of magnitude improvement in their barrier /polarization resistance (Rp) values at ∼ 100 MΩ.cm2 suggesting the effectiveness of the SHP coatings as a barrier against corrosion in neutral chloride environments. However, the Rp values (∼ 10 M Ω.cm2) of the SHP coatings obtained from the PDP analysis were an order of magnitude lower than the Rp values derived from the EIS. SHP CP-Ti samples showed dual passive range behaviour with an initial narrow passive region due to the porous anodized TiO2-xCly layer while the later stage passivity due to the barrier TiO2 layer, where the outer anodized porous TiO2-xCly layer was less effective against corrosion in neutral chloride media. Detailed analysis showed that in PDP, the sample lost its SHP because of the permeation of electrolyte into the hierarchical surface, due to its sensitivity to polarization, owing to the lower thickness of the organic layers. The mechanism involved in the loss of SHP and the limitation of the PDP technique for the corrosion analysis of SHP / organic coatings on metal surfaces is highlighted.

Novel core-shell structural nZVI@Fe2P for sulfadiazine (SDZ) degradation: Accelerated Fe(III)/Fe(II) dynamic cycling, boosted Fenton performance and stability

Nano zero valent iron (nZVI) is widely used in traditional hydrogen peroxide (H2O2)-based Fenton reactions for the degradation of persistent organic pollutants in aqueous environments. How to restrain the blocked electron transfer aroused from thickening of the iron oxide passivation layer and reinforce the Fe(III)/Fe(II) dynamic cycling is essential for Fenton reactions. In this work, a novel core–shell structural nZVI@Fe2P was fabricated and employed for the degradation of sulfadiazine (SDZ). Compared to nZVI, the nZVI@Fe2P demonstrated a significant performance and stability in the degradation of SDZ. Completed SDZ removal is achieved in less than 15 min and the SDZ removal kept over 60% even in the ninth consecutive cycles. Although the SDZ removal decreased dramatically to only 27.4% in the tenth cycle, the value could be restored to 80.6% after a facile re-phosphorization process. Both experimental and density function theory (DFT) calculation revealed the dominant role of Fe2P in promoting H2O2 activation and strengthening the Fe(III)/Fe(II) dynamic cycling. In the nZVI@Fe2P/H2O2 system, the low impedance and high proton conductivity of the Fe2P shell layer played a dual function, i.e., accelerating electron transfer and donating electrons for the continuous Fenton reaction. This implication of these findings provides a novel strategy by integrating the state-of-the-art material science, advanced oxidation process, and mechanism elucidation for practical environmental wastewater remediation.

Exposures and Health Effects of Diacetyl and 2,3-Pentanedione in a Coffee Processing Facility

Diacetyl and 2,3-pentanedione are alpha-diketones that are generated during the coffee roasting process and have been shown to be related to respiratory symptoms, abnormal lung function, and in rare cases, an irreversible disease called obliterative bronchiolitis. This study measured personal exposures in a coffee roastery in New Zealand using thermal desorption tubes and explored the prevalence of respiratory symptoms with a health questionnaire. Exposures from task samples were highest for grinding (Geometric Mean (GM): 22.5 ppb diacetyl; GM: 19.3 ppb 2,3-pentanedione), followed by packaging (GM: 10.8 ppb diacetyl; GM: 9.3 ppb 2,3-pentanedione) and then roasting (GM: 4.7 ppb diacetyl; GM: 4.1 ppb diacetyl). 8-h time-weighted average (TWA) diacetyl exposures exceeded the National Institute of Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL) of 5 ppb for Roaster/Packager (GM: 6.6 ppb) and Grinder (GM: 5.3 ppb). 8-h TWA concentrations were below the NIOSH REL of 9.3 ppb for 2,3-pentanedione (Roaster/Packager, GM: 5.7 ppb; Grinder, GM: 4.6 ppb). Workers reported nose, eye symptoms and systemic symptoms (flu-like illness or achy joints, fever or chills, or unusual tiredness or fatigue). The results indicated that exposure was highest for tasks involving ground coffee beans and that coffee processing workers can be exposed to alpha-diketones above the NIOSH RELs. Further research into alpha-diketone exposure and health effects, and control measures to minimise exposure are recommended.

K-ion preintercalated MnO2 nanorods as a high-rate cathode material for aqueous zinc-ion batteries

The integration of Zn/α-MnO2 in aqueous zinc-ion batteries (ZIBs) has emerged as a promising avenue owing to their eco-friendliness, facile manufacturability, cost-effectiveness, low flammability, and commendable electrochemical performance. However, the intrinsic limitation in the rate capability of α-MnO2 constitutes a significant impediment to its practical application. In this study, we introduce K-ion preintercalated nanorods (K-MnO2-NR) with a diameter of approximately 10 nm as a cathode material for ZIBs. The synthesis of K-MnO2-NR entails a facile one-step electrochemical participation method, whereby K-ion are electrochemically intercalated into the tunnel-structured α-MnO2. The incorporation of K-ion serves a dual purpose of enhancing the electrical conductivity of manganese oxides and stabilizing the tunnel structure. Consequently, K-MnO2-NR manifests exceptional rate capability, exhibiting a specific capacity of 222 mAh g−1 at 2 A g−1, coupled with outstanding cycling stability (with negligible capacity decay observed over 1450 cycles at 2 A g−1). The facile and scalable synthesis process underscores its potential for large-scale production and eventual commercialization in pouch cells for energy storage applications.

Significance of Formamidinium Incorporation in Perovskite Composition and Its Impact on Solar Cell Efficiency: A Mini‐Review

Perovskite solar cells (PSCs) have gained tremendous research interest recently owing to several advantages, including low material cost, facile solution processability, bandgap tunability, and alluring device efficiency. The organic formamidinium (FA) cation‐based perovskites are mainly considered as one of the potential candidates for charge carrier generation due to their excellent properties, such as bandgap and thermal stability than traditional perovskites. However, the inevitable unfavorable polymorphism (i.e., α to δ) at room temperature still forms the basis for numerous research works to allow the fabrication of a high‐quality absorber and enhances the PSCs performance. The studies to resolve the polymorphism and several contemporary techniques (e.g., passivation strategy) with several recent novel fabrication methods presented in this review form the essence of the improvements in PSCs. The absorber morphology also influences the charge‐transfer behavior and the device's lifetime. Therefore, understanding these properties is essential to improve the absorber quality and avoid many defects. This review focuses on the structure and properties of pure and mixed FA perovskites with various halides, mainly the FA cation's role in the absorber composition. And a comprehensive overview of recent FA cation‐based double, triple, and quadrupole PSCs results with proper scientific explanations to understand the device physics.

Detection of the lactic acid bacterial community in small scale white cheese processing facility using shotgun metagenomics and culturomics

This study aims to characterize lactic acid bacteria (LAB) community in small-scale white cheese processing facility highly favored by consumers. Shotgun metagenomics and culturomics based on MALDI-TOF MS approaches were employed. Samples from various production stages and equipment surfaces were collected. Dominant phyla in dairy and equipment samples were Firmicutes (63–70%) and Proteobacteria (84–89%), respectively. Lactococcus was the most abundant LAB genus across all samples, with Lactococcus lactis as dominant species followed by Streptococcus, Enterococcus, and Lactobacillus, indicating LAB community diversity contributing to product characteristics. Culturomics identified 12 LAB species, including Enterococcus faecalis and Lactobacillus delbrueckii. Metagenomics provided insights into microbial composition and dynamics in dairy environment, while culturomics identified specific LAB species. The combined approach offers a comprehensive view of dairy microbial communities, aiding industrial development by informing starter culture combinations for improved dairy products and processes.

AIseed Simulation: A seed simulation sorting software for rapidly determining seed processing procedures and parameters

Seed processing is a crucial measure for improving seed quality after harvest. However, traditional seed processing procedures and parameter settings have largely depended on technicians' operational experience. To enhance the digitization of the seed processing procedures, AIseed Simulation software was developed and incorporates ''Simulated sorting'' and ''One-click sorting'' based on RGB images of seeds and impurities. Based on the sorting principles of current main seed sorting equipment, length, width, thickness, specific gravity, and color features (R, G, B, R/G, R/B, G/B) are selected. Through Spearman correlation analysis and probability density distribution plots, the sorting features and parameters are determined. By repeatedly comparing precision, recall, and F1 values of different sorting combinations, simulation sorting on a computer is achieved. The ''One-click sorting'' function has been integrated into the above procedures, facilitating automation and making the determination of optimal seed processing procedures and parameters easier and more rapid. The AIseed Simulation was individually validated on five crop seeds—Astragalus membranaceus, Perilla frutescens, Scutellaria baicalensis, Bupleurum chinense, and Platycodon grandiflorus—and the processing procedures and parameters established for each seed type were validated with actual processing equipment. The results validated that AIseed Simulation is a stand-alone, automated RGB image processing platform suitable for seed processing and parameter setting. Furthermore, the AIseed Simulation software exhibits versatility in a range of seed processing scenarios, suitable for both large-scale seed processing facilities and the demands of scientific research and education. These findings contribute significantly to enhancing seed quality and facilitate the intelligent development of the seed processing industry.

Rapidly reducing cadmium from contaminated farmland soil by novel magnetic recyclable Fe3O4/mercapto-functionalized attapulgite beads

Reducing cadmium (Cd) content from contaminated farmland soils remains a major challenge due to the difficulty in separating commonly used adsorbents from soils. This study synthesized novel millimeter-sized magnetic Fe3O4/mercapto-functionalized attapulgite beads (MFBs) through a facile one-step gelation process incorporating alginate. The MFBs inherit the environmental stability of alginate and enhance its mechanical strength by hybridizing Fe3O4 and clay mineral components. MFBs can be easily separated from flooded soils by magnets. When applied to 12 Cd-polluted paddy soils and 14 Cd-polluted upland soils, MFBs achieved Cd(II) removal rates ranging from 16.9% to 62.2% and 9.8%–54.6%, respectively, within a 12-h period. The MFBs predominantly targeted the exchangeable and acid soluble, and reducible fractions of Cd, with significantly enhanced removal efficiencies in paddy soils compared to upland soils. Notably, MFBs exhibited superior adsorption performance in soils with lower pH and organic matter (OM) content, where the bioavailability and mobility of Cd are heightened. The reduction of Cd content by MFBs is a sustainable and safe method, as it permanently removes the bioavailable Cd from soil, rather than temporarily reducing its bioavailability. The functional groups such as –SH, –OH, present in attapulgite and alginate of MFBs, played a crucial role in Cd(II) adsorption. Additionally, attapulgite and zeolite provided a porous matrix structure that further enhanced Cd(II) adsorption. The results of X-ray photoelectron spectroscopy suggested that both chemical precipitation and surface complexation contributed to Cd(II) removal. The MFBs maintained 87.6% Cd removal efficiency after 5 regeneration cycles. The surface of the MFBs exposed new adsorption sites and increased the specific surface area during multiple cycles with Cd-contaminated soil. This suggests that MFBs treatment with magnetic retrieval is a potentially effective pathway for the rapid removal of Cd from contaminated farmland soils.

Factors influencing integration of mental health screening and treatment at HIV clinic settings in Cameroon: a qualitative study of health providers’ perspectives

BackgroundMental disorders are common among people with HIV (PWH) and are associated with poor HIV outcomes. Despite high unmet mental health needs among PWH, use of evidence-based mental health screening and treatment protocols remains limited at HIV treatment facilities across low-resource settings. Integrating mental health services into HIV care can reduce this gap. This study’s objective was to explore factors that influence integration of mental health screening and treatment into HIV clinics in Cameroon.MethodsWe analyzed 14 in-depth interviews with clinic staff supporting PWH at three urban HIV treatment clinics in Cameroon. Interviews focused on current processes, barriers and facilitators, and types of support needed to integrate mental health care into HIV care. Interviews were recorded and transcribed. French transcripts were translated into English. We used thematic analysis to identify factors that influence integration of mental health screening and treatment into HIV care in these settings. Ethical review boards in the United States and Cameroon approved this study.ResultsRespondents discussed a lack of standardized mental health screening processes in HIV treatment facilities and generally felt ill-equipped to conduct mental health screening. Low community awareness about mental disorders, mental health-related stigma, limited physical space, and high clinic volume affected providers’ ability to screen clients for mental disorders. Providers indicated that better coordination and communication were needed to support client referral to mental health care. Despite these barriers, providers were motivated to screen clients for mental disorders and believed that mental health service provision could improve quality of HIV care and treatment outcomes. All providers interviewed said they would feel more confident screening for mental disorders with additional training and resources. Providers recommended community sensitization, training or hiring additional staff, improved coordination to manage referrals, and leadership buy-in at multiple levels of the health system to support sustainable integration of mental health screening and treatment into HIV clinics in Cameroon.ConclusionsProviders reported enthusiasm to integrate mental health services into HIV care but need more support and training to do so in an effective and sustainable manner.

Nanofibrils from oil palm trunk: effect of delignification and fibrillation technique

Oil palm trunk (OPT) is an inexpensive, abundantly available by-product of palm oil production which is typically not put to material use. Due to its comparably high cellulose content, OPT represents a suitable raw material for the preparation of cellulose nanofibrils (CNFs). Aiming for full utilization of the raw material and minimized energy demand, non-delignified and partially delignified (alkali-pretreated) OPT was subjected to mechanical fibrillation in the present study. As compared to CNFs from fully delignified OPT, the lignin-rich microfibrils obtained by this approach generally showed higher average fibril diameters, lower thermal stability as well as lower viscosity, and higher sedimentation rate in suspension. However, the combination of alkali-pretreatment and fibrillation by disc-grinding and subsequent high-pressure homogenization resulted in fibrils with properties similar to those of CNFs from fully delignified OPT. As proven by IR-spectroscopy, thermogravimetry and chemical composition analysis, alkali-treated OPT fibrils still contained substantial amounts of residual lignin which could, for instance, act as a natural coupling agent or binder in composite applications. Moreover, the facile delignification process applied herein requires far less chemicals and energy than conventional pulping and is thus beneficial from both the economic and ecological perspective.

Phyto-mediated synthesis of Ag, ZnO, and Ag/ZnO nanoparticles from leave extract of Solanum macrocarpon: Evaluation of their antioxidant and anticancer activities

Silver, zinc oxide, and silver/zinc oxide nanocomposites were prepared from the facile green process using Solanum macrocarpon leave extract. Ag and ZnO nanoparticles (NPs) were composited with the aim of enhancing the synergy for improved antioxidant and anticancer activities. In the synthesis process, the formation of Ag NPs was initially observed by a colour change and was confirmed by the appearance of surface plasmon resonance (SPR) bands. Based on the crystallographic analysis of the diffraction patterns, the phyto-capped silver NPs possessed a crystalline character, featuring a lattice structure of face-centered cubic (FCC) and an estimated crystallite size of around 7.2 nm. The formation of a hexagonal crystal structure of spherical morphology was confirmed for the ZnO, while the Ag/ZnO composite showed additional planes due to the silver nanoparticles in the cubic phase. The scavenging activities of 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radicals and their anticancer potency on normal HEK and cancerous HELA cells were examined in comparison to standard drugs. They demonstrated remarkable IC50 values that were better than the control drugs. This study provides helpful insight into the synergy between Ag and ZnO nanoparticles for the possible development of new anticancer and antioxidant agents.

Identification of Protein Biomarkers for Differentiating Listeria monocytogenes Genetic Lineage III.

Listeria monocytogenes is the causative agent of listeriosis, a severe foodborne illness characterized by septicemia, meningitis, encephalitis, abortions, and occasional death in infants and immunocompromised individuals. L. monocytogenes is composed of four genetic lineages (I, II, III, and IV) and fourteen serotypes. The aim of the current study was to identify proteins that can serve as biomarkers for detection of genetic lineage III strains based on simple antibody-based methods. Liquid chromatography (LC) with electrospray ionization tandem mass spectrometry (ESI MS/MS) followed by bioinformatics and computational analysis were performed on three L. monocytogenes strains (NRRL B-33007, NRRL B-33014, and NRRL B-33077), which were used as reference strains for lineages I, II, and III, respectively. Results from ESI MS/MS revealed 42 unique proteins present in NRRL B-33077 and absent in NRRL B-33007 and NRRL B-33014 strains. BLAST analysis of the 42 proteins against a broader panel of >80 sequenced strains from lineages I and II revealed four proteins [TM2 domain-containing protein (NRRL B-33077_2770), DUF3916 domain-containing protein (NRRL B-33077_1897), DNA adenine methylase (NRRL B-33077_1926), and protein RhsA (NRRL B-33077_1129)] that have no homology with any sequenced strains in lineages I and II. The four genes that encode these proteins were expressed in Escherichia coli strain DE3 and purified. Polyclonal antibodies were prepared against purified recombinant proteins. ELISA using the polyclonal antibodies against 12 L. monocytogenes lineage I, II, and III isolates indicated that TM2 protein and DNA adenine methylase (Dam) detected all lineage III strains with no reaction to lineage I and II strains. In conclusion, two proteins including TM2 protein and Dam are potentially useful biomarkers for detection and differentiation of L. monocytogenes lineage III strains in clinical, environmental, and food processing facilities. Furthermore, these results validate the approach of using a combination of proteomics and bioinformatics to identify useful protein biomarkers.

Reducing the SiOx layer on Si/reduced graphene oxide enables fast and reversible lithium-ion storage capability for lithium-ion batteries

To investigate whether the presence of a SiOx layer affects the electrochemical performance of silicon-based materials, particularly the silicon-carbon anode material, a facile and scalable process involving HCl etching, annealing, and HF etching was employed to synthesize a silicon-carbon composite (Si/SiOx-rGO) and reduce the SiOx layer content at the silicon-carbon interface to obtain a Si-rGO composite. Experimental results demonstrate that this method effectively reduces the SiOx content in the composite. By decreasing the SiOx layer content, the Si-rGO composite exhibits the specific capacities of 758.3 mAh g−1 at 3 A g−1 and 557 mAh g−1 at 5 A g−1. After 200 cycles at 2 A g−1, it still retains a capacity of 930.8 mAh g−1. These findings offer comprehensive insights into the SiOx layer at the silicon-carbon interface, thereby enhancing the application of silicon-based anode materials.

Skin‐Mount Textile‐Based Flexible Strain Sensors for Physiotherapy

Tremendous development in intelligent wearable gadgets creates opportunities for flexible strain sensors. Comfortable and safe flexible strain sensors have high demand in wearable applications and therefore the textile‐based strain sensors are desired. Achieving attributes like easy fabrication, cost‐effectiveness, high sensitivity, good stability, and portability is still a challenge to overcome. In this regard, textile‐based flexible strain sensors, one on jeans fabric and other on cotton fabric, are presented. A conventional interdigitated electrode structure is adopted and sensors are prepared by facile and economical fabrication process. Both sensors own high sensitivity factors, i.e., gauge factor >200 and stability of ≈10 000 cycles. The anticipated works show a linear response R2 = 0.99, low hysteresis <5%, and minimum resolution <7°. The intended sensors are implemented for real‐time application, i.e., the physiotherapy of the knee and neck. The jeans‐fabric‐based sensor is used for knee therapy and the cotton for neck. The daily therapy sessions are recorded and examined. The sensors respond well to the applied strain during therapy sessions, proving to be an outstanding choice for integration into biomedical wearable devices for therapeutic purposes. The proposed sensors can also be auspicious candidates for targeting many other wearable applications.

Fabrication of robust superhydrophobic myristic acid/ZrO2 coating with improved anti-icing and anti-corrosion for concrete via a two-step method

To address the safety concerns associated with icing and corrosion of concrete-based facilities, a facile two-step process of sandpaper covering and spraying for fabricating a robust superhydrophobic myristic acid/ZrO2 coating (MAZ-RSC) on concrete surface was proposed. Sandpaper covering and ZrO2 modified with myristic acid were used to fabricate the superhydrophobic structure. An analysis of the resultant superhydrophobic concrete's surface morphology and chemical structure was performed. The formation mechanism of the obtained MAZ-RSC was discussed. Results indicate that the MAZ-RSC coating exhibited superior superhydrophobic and self-cleaning properties with a contact angle of 161.3° and a sliding angle of 1.2°. The robust ability of the as-prepared MAZ-RSC coating was assessed through knife scratching, tape peeling, and sandpaper abrasion. The presence of ZrO2 enabled the MAZ-RSC to be a superhydrophobic hard coating. Meanwhile, the prepared coating was proven to possess a good active anti-icing ability and a strong anti-corrosion ability and to be easily de-iced. Further tests show that this coating can maintain excellent chemical resistance across a broad pH range because of its superior hydrophobicity and the chemical inertness of the ZrO2 particles. Thus, the as-prepared coating is expected to be adopted in practical areas such as roads, buildings and bridges.

High‐Performance Thermoelectric and Electromagnetic Interference Shielding Derived from MXene/Ag2Se Nanowire Composite Film

AbstractA flexible n‐type composite film consisting of MXene/Ag2Se nanowires (MX‐AS), is synthesized herein via a facile wet chemical sintering process. The thermoelectric properties of the composites with various MXene concentrations are systematically explored. The as‐synthesized 2D MXene exhibits homogeneous intercalation and dispersion of the Ag2Se nanowires. A comparative analysis reveals that these composite films outperform the pristine Ag2Se nanowire films fabricated using the same process. Specifically, the MX‐AS composite film containing 1.5 wt.% MXene exhibits a significant (≈1.25 times) improvement in the maximum thermoelectric power factor (PF), exhibiting a value of ≈933.4 µW m−1 K−2 at 400 K. This enhancement can be attributed to the combination of the remarkable intrinsic Seebeck coefficient of the Ag2Se and the high electrical conductivity of the MXene. Moreover, cyclic bending tests demonstrate the exceptional mechanical durability and flexibility of the composite film, with only an ≈7% decrease in the PF after 1000 cycles. In addition, the as‐prepared MX‐AS composite exhibits a high electromagnetic interference (EMI) shielding efficiency.

Adaptative comfort modeling for a typical non-centrifugal cane sugar processing facility

The production of non-centrifuged cane sugar in Colombia takes place in post-harvest facilities that generate significant heat and steam resulting from the evaporation of cane juices during the process. This study aimed to improve the comfort conditions of a facility of this type in the municipality of Pacho, Cundinamarca, Colombia, through bioclimatic simulation, where the enclosure on the walls and the lantern window were modified. The evaluation of adaptative thermal comfort revealed that configurations with open perimeter and lantern window demonstrated the best bioclimatic behavior. This is attributed to the increased ventilation area and chimney effect, which optimizes the transfer of heat and mass. Likewise, it was observed that there is a generalized behavior of thermal discomfort for workers in the thermal zone of the oven, due to the high emissions of heat and steam in this specific area.

Design of an improved layout for a steel processing facility using SLP and lean Manufacturing techniques

Implementing lean manufacturing practices in the systematic layout planning (SLP) process for improving facility layouts in various industries is essential. This approach enhances material handling processes and effectively manages space utilization. An efficient plant employing systematic layout planning leads to improved resource utilization and facilitates the integration of lean manufacturing techniques such as value stream mapping, 5 S, Ohno’s 7 wastes, and cellular manufacturing. This research article presents a case study on a steel processing plant in Dubai with an area of 160 m × 160 m, where systematic layout planning and lean manufacturing techniques were applied. The factors considered included space and material flow optimization, incorporating layout alternatives based on systematic layout planning principles along with lean manufacturing techniques. The study revealed a 34% reduction in material flow and an efficient overall space utilization improvement of 26%. Additionally, cost analysis validation was conducted.

Efficient synthesis of high-purity carbon dots via self-polymerization driven bottom-up growth for high-selectivity sensing and high-efficiency separation

Carbon dots (CDs) have attracted extensive interest due to their exceptional optical properties and facile synthesis processes. However, achieving high-efficiency synthesis of high-purity CDs with high yield remains an unresolved critical issue. Herein, we report a facile and versatile self-polymerization-driven bottom-up growth strategy for efficient fabrication of high-purity CDs. As a proof-of-concept demonstration, dopamine and its four analogues were used as the self-polymerizable precursors for self-driven synthesis of fluorescent CDs with high-purity. By employing a mixed-solvent system and rationally regulating periodate oxidation process, the highly controllable self-polymerization processes and efficient solvothermal-assisted production of polydopamine and polyphenols derived CDs were readily achieved. Further integrating high molecular weight membrane dialysis, we successfully obtained the highly purified polydopamine-derived CDs with high yield of 21.1 % and quantum yield of 3.6 %, confirmed by nuclear magnetic resonance, capillary electrophoresis and other types of high-resolution characterization techniques. The formation and luminescence mechanisms of the self-polymerized CDs were also elucidated through comparative analysis of their morphological features and elemental compositions. We also demonstrated the broad universality of this self-polymerization driven bottom-up strategy by utilizing by employing four other phenolic compounds, including l-dopa, gallic acid, catechol, and pyrogallol, as readily accessible precursors for high-yield synthesizing highly purified fluorescent CDs. Moreover, the enormous application potential of the high-purity CDs for high-selectivity sensing and high-efficiency electrochromatographic separation was thoroughly demonstrated.

Hierarchical Cu3V2O8/Cu6Mo5O18/MXene nanostructures by ultrathin nanosheets for highly sensitive electrochemical detection of organophosphorus pesticides

Transition-metal oxides (TMOs) with hierarchical nanostructures derived from metal organic frameworks (MOFs) were widely applied in electrochemical investigation. In this paper, a rational synthesis strategy of TMOs with specific nanostructures and multiple components was reported. Three-dimensional (3D) CuMoV layered metal hydroxides (CuMoV LDHs) architecture was prepared by mild and facile wet-chemistry process to reshape Cu-MOF surface and realize the self-templated conversion. After thermal annealing, hierarchical CuMoV LDHs were transformed to polynary Cu3V2O8/Cu6Mo5O18 (CMVO) compounds. Based on the electrostatic attraction, CMVO/MXene (CMVON) compounds were assembled by combining the CMVO and few-layer Nb2CTx MXene (f-Nb2C) nanosheets and employed as modified materials on the electrode surface. Benefiting from the superior electronic conductivity, large surface area and shortened ion diffusion pathway, the CMVON hybrids demonstrated excellent electrochemical sensing properties. Upon optimum conditions, the constructed CMVON based AChE biosensor manifested markedly analytical performance with the low limit of detection (LOD) and wide linear ranges for parathion-methyl, malathion, and fenitrothion detection.