Dispersed Cu₂O octahedrons on h-BN nanosheets for p-nitrophenol reduction

Green NiO nanoparticle-integrated PVA-alginate hydrogel: potent nanocatalyst for efficient reduction of anthropogenic water pollutants

Hydrogel nanocatalyst composed of nickel oxide (NiO) nanoparticles embedded in PVA-alginate hydrogels were potentially explored toward the reduction of anthropogenic water pollutants. The NiO nanoparticles was accomplished via green method using waste pineapple peel extract. The formation of the nanoparticles was affirmed from different analytical techniques such as UV-Vis, FTIR, XRD, TGA, FESEM, and EDS. Spherical NiO nanoparticles were obtained having an average size of 11.5 nm. The nano NiO were then integrated into PVA-alginate hydrogel matrix forming a nanocomposite hydrogel (PVALg@ NiO). The integration of nano NiO rendered an improved thermal stability to the parent hydrogel. The PVALg@ NiO hydrogel was utilized as a catalyst in the reduction of 4-nitrophenol (4-NP), potassium hexacyanoferrate (III), rhodamine B (RhB), methyl orange (MO), and malachite green (MG) in the presence of a reducing agent, i.e., NaBH4. Under optimized conditions, the reduction reactions were completed by 4.0 min and 3.0 min for 4-NP and potassium hexacyanoferrate (III), respectively, and the rate constant was estimated to be 1.14 min-1 and 2.15 min-1. The rate of reduction was found to be faster for the dyes and the respective rate constants were be 0.17 s-1 for RhB, MG and 0.05 s-1 for MO. The PVALg@ NiO hydrogel nanocatalyst demonstrated a recyclability of four runs without any perceptible diminution in its catalytic mettle. The efficacy of the PVALg@ NiO hydrogel nanocatalyst was further examined for the reduction of dyes in real water samples collected from different sources and the results affirm its high catalytic potential. Thus, this study paves the path for the development of a sustainable hydrogel nanocatalyst for reduction of hazardous pollutants in wastewater treatment.

Electron transfer enhanced catalytic activity of nitrogen doped reduced graphene oxide supported CuCo2O4 towards the fast reduction of 4-nitrophenol in water

There has been a growing interest in the design and development of graphene based composite materials with superior performances for environmental catalytic applications. But in most of the studies the synthesis conditions require elevated temperatures and expensive working setups (high temperature furnaces, autoclaves, inert atmosphere conditions etc.). In this reported work, the nitrogen doped reduced graphene oxide supported CuCo2O4 (NG/CuCo2O4) composites were prepared through a simple one pot synthesis method under mild conditions (∼95 °C and air atmosphere) and successfully employed as catalysts for the reduction of toxic 4-nitrophenol (4NP). The characterization results revealed the successful formation of NG/CuCo2O4 composites with a possible charge transfer interaction between nitrogen doped reduced graphene oxide support of CuCo2O4. The NG/CuCo2O4 hybrids exhibited robust catalytic activity in 4NP reduction with an activity factor of 261.5 min-1 g-1. A 4NP conversion percentage which is as high as 99.5% was achieved within 11 min using the NG/CuCo2O4 catalyst. The detailed kinetic analysis confirmed the Langmuir-Hinshelwood model for the NG/CuCo2O4 catalysed 4NP reduction. The nitrogen doped reduced graphene oxide support modified the electronic levels of CuCo2O4 nanoparticles through electron transfer interactions and enhanced the catalytic activity of CuCo2O4 in NG/CuCo2O4 through improved adsorption of reactant ions and effective generation of active hydrogen species. The good reusability and stability along with profound activity of NG/CuCo2O4 catalyst makes it a promising material for wide scale catalytic applications.

Advanced Functionalized Nanoclusters (Cu, Ag, and Au) as Effective Catalyst for Organic Transformation Reactions

A considerable amount of research has been carried out in recent years on synthesizing metal nanoclusters (NCs), which have wide applications in the field of optical materials with non-linear properties, bio-sensing, and catalysis. Aside from being structurally accurate, the atomically precise NCs possess well-defined compositions due to significant tailoring, both at the surface and the core, for certain functionalities. To illustrate the importance of atomically precise metal NCs for catalytic processes, this review emphasizes 1) the recent work on Cu, Ag, and Au NCs with their synthesis, 2) the parameters affecting the activity and selectivity of NCs catalysis, and 3) the discussion on the catalytic potential of these metal NCs. Additionally, metal NCs will facilitate the design of extremely active and selective catalysts for significant reactions by elucidating catalytic mechanisms at the atomic and molecular levels. Future advancements in the science of catalysis are expected to come from the potential to design NCs catalysts at the atomic level.

Efficient Removal and Recovery of Ag from Wastewater Using Charged Polystyrene-Polydopamine Nanocoatings and Their Sustainable Catalytic Application in 4-Nitrophenol Reduction

This study addresses the long-standing challenges of removing and recovering trace silver (Ag) ions from wastewater while promoting their sustainable catalysis utilization. We innovatively developed a composite material by combining charged sulfonated polystyrene (PS) with a PDA coating. This composite serves a dual purpose: effectively removing and recovering trace Ag+ from wastewater and enabling reused Ag for sustainable applications, particularly in the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The PS-PDA demonstrated exceptional selectivity to trace Ag+ recycling, which is equal to 14 times greater than the commercial ion exchanger. We emphasize the distinct roles of different charged functional groups in Ag+ removal and catalytic reduction performance. The negatively charged SO3H groups exhibited the remarkable ability to rapidly enrich trace Ag ions from wastewater, with a capacity 2-3 times higher than that of positively-N+(CH3)3Cl and netural-CH2Cl-modified composites; this resulted in an impressive 96% conversion of 4-NP to 4-AP within just 25 min. The fixed-bed application further confirmed the effective treatment capacity of approximately 4400 L of water per kilogram of adsorbent, while maintaining an extremely low effluent Ag+ concentration of less than 0.1 mg/L. XPS investigations provided valuable insights into the conversion of Ag+ ions into metallic Ag through the enticement of negatively charged SO3H groups and the in situ reduction facilitated by PDA. This breakthrough not only facilitates the efficient extraction of Ag from wastewater but also paves the way for its environmentally responsible utilization in catalytic reactions.

A density functional theory study on the adsorption of Mercaptopurine anti-cancer drug and Cu/Zn-doped boron nitride nanocages as a drug delivery

Targeted drug delivery along with the most negligible side effects, is the most important challenge in the designing of the novel anti-cancer drug delivery. Therefore, the interaction of Cu/Zn-doped boron nitride nanocages as the carrier for Mercaptopurine (MP) anti-cancer drug was studied by density functional theory calculations to design a novel carrier. The adsorption of MP drug on Cu/Zn-doped boron nitride nanocages is suitable energetically. In this study, electronic parameters and Gibbs free energy of complexes of Cu/Zn-doped boron nitride nanocages with two configuration MP drug (N and S) were investigated. In addition, CuBN has a short recovery time, but ZnBN has more selectivity for MP drug. It is predicted that the MP drug over both Cu/Zn-doped boron nitride nanocages can be used as a suitable drug delivery system. Configuration -S of MP drug in both nanocage is more appropriate than configuration -N. Analysis of frontier molecular orbitals, UV-VIS spectra and density of states plots of the designed complexes confirmed adsorption MP drug on Cu/Zn-doped boron nitride nanocages. This research predicted which Cu/Zn-doped boron nitride nanocages can be used as acceptable carriers for MP anti-cancer drug.Communicated by Ramaswamy H. Sarma.

Construction of High Energy Nanoscale Lead Azide Composite with Improved Flame Sensibility from Intercalated Hydroxide

It is of great significance to develop efficient methods for preparing high-content modified nanoscale lead azide (LA) composites used in microinitiating devices. In this work, a structurally controllable salicylate-intercalated lead hydroxide with a nanoscale mesoporous structure is designed. Using it as a precursor, carbon-based lead azide (LA/C) and salicylate-based lead azide (LA/SA) are fabricated by the gas-solid azidation of the framework (GAF) method within 3 h, greatly reducing the preparation time of nano-LA composites. The characterizations of the composites demonstrate that the Pb in the precursors is transformed into nanoscale LA attached to the salicylate radical or its carbonized skeleton. Due to the unique embedded nanostructures and excellent electrical and thermal conductivity of salicylate-derived carbon materials, LA/C exhibits excellent electrostatic safety (E50 = 0.25 J) and flame sensitivity (H50 = 28 cm). The adjustable organic-inorganic ratio of intercalated hydroxides allows the LA content in LA/C to reach as high as 92.5%, enabling 6.50 mg of LA/C to successfully detonate secondary explosive CL-20 in a microinitiating device, demonstrating an amazing detonation ability superior to other reported LA complexes. The research provides a new perspective for the development of nanoscale LA composites with high LA content and appropriate sensitivity.

Smart crystalline framework materials with a triazole carboxylic acid ligand: fluorescence sensing and catalytic reduction of PNP

Triazole polycarboxylic acid ligands are widely employed in the construction of MOFs due to their strong coordination ability and flexible coordination modes. In this work, three novel complexes (Pb(MCTCA)(H2O) (1), Co(HMCTCA)2(H2O)2 (2) and Cu(HMCTCA)2(H2O)2 (3)) based on the H2MCTCA ligand (5-methyl-1-(4-carboxyl)-1H-1,2,3-triazole-4-carboxylic acid) were successfully synthesized under hydrothermal conditions, respectively. X-ray single crystal structure analysis shows that complex 1 is a 3D network structure, where the central metal Pb(II) is six coordinated to form deformed triangular prism geometry. The complexes 2 and 3 are both 2D layer supramolecular structures connected through intermolecular hydrogen, where the central metals (Co/Cu) are six coordinated to form octahedral configuration geometry. Based on functional properties, it is found that complex 1 exhibits excellent detection ability for small-molecule drugs (azithromycin, colchicine and balsalazide disodium) and actinide cations (Th4+ and UO22+) within a lower concentration range without interference from other components. In particular, the detection limits of three small-molecule drugs are all lower than 0.30 μM. In addition, complexes 2 and 3 exhibited excellent catalytic reduction performance toward p-nitrophenol (PNP), with a reduction efficiency exceeding 98%. These experimental results evidence that complexes 1-3 have potential application prospects in fluorescence sensing and catalytic reduction.

CuO/TiO2/ZnO NPs Anchored Hydrogen Exfoliated Graphene: To Comprehend the Role of Graphene in Catalytic Reduction of p-Nitrophenol

The present study deals with sonochemically in situ synthesis of a novel functional catalyst using hydrogen exfoliated graphene (HEG) supported titanium dioxide (TiO2) and copper sulfate (CuSO4) doped with zinc oxide (ZnO) (abbreviated as Ti/Cu/Zn-HEG). The synthesis of the Ti/Cu/Zn-HEG nanocomposite (NCs) catalyst was confirmed through its characterizations by XRD, SEM-EDX, TEM, XPS, FTIR, and BET methods. It was assessed for catalytic conversion of a model aromatic compound para-nitrophenol (p-NP) in an aqueous solution. The p-NP is a nitroaromatic compound that has a toxic and mutagenic effect. Its removal from the water system is necessary to protect the environment and living being. The newly synthesized Ti/Cu/Zn-HEG NCs were applied for their higher stability and catalytic activity as a potential candidate for reducing p-NP in practice. The operating parameters, such as p-NP concentration, catalyst dosage, and operating time were optimized for 150 ppm, 400 ppm, and 10 min through response surface methodology (RSM) in Design-Expert software to obtain the maximum reduction p-NP up to 98.4% at its normal pH of 7.1 against the controls (using HEG, Ti/Cu-HEG, and Zn-HEG). Analysis of variance of the response suggested the regression equation to be significant for the process with a major impact on catalyst concentration and operating time. The model prediction data (from RSM) and experimental data were corroborated well as reflected through model's low relative error (RE < 0.10), high regression coefficient (R2 > 0.97), and Willmott d-index (dwill-index > 0.95) values.

Recent advances in nano-scaffolds for tissue engineering applications: Toward natural therapeutics

Among the promising methods for repairing or replacing tissue defects in the human body and the hottest research topics in medical science today are regenerative medicine and tissue engineering. On the other hand, nanotechnology has been expanded into different areas of regenerative medicine and tissue engineering due to its essential benefits in improving performance in various fields. Nanotechnology, a helpful strategy in tissue engineering, offers new solutions to unsolved problems. Especially considering the excellent physicochemical properties of nanoscale structures, their application in regenerative medicine has been gradually developed, and a lot of research has been conducted in this field. In this regard, various nanoscale structures, including nanofibers, nanosheets, nanofilms, nano-clays, hollow spheres, and different nanoparticles, have been developed to advance nanotechnology strategies with tissue repair goals. Here, we comprehensively review the application of the mentioned nanostructures in constructing nanocomposite scaffolds for regenerative medicine and tissue engineering. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement Diagnostic Tools > Biosensing.

Ultrasensitive Bio-H2S Gas Sensor Based on Cu2O-MWCNT Heterostructures

Developing a respiratory analysis disease diagnosis platform for the H2S biomarker has great significance for the real-time detection of various diseases. However, achieving highly sensitive and rapid detection of H2S gas at the parts per billion level at low temperatures is one of the most critical challenges for developing portable exhaled gas sensors. Herein, Cu2O-multiwalled carbon nanotube (MWCNT) heterostructures with excellent gas sensitivity to H2S at room temperature and a lower temperature were successfully synthesized by a facile two-dimensional (2D) electrodeposition in situ assembly method. The combination of Cu2O and MWCNTs via the principle of optimal conductance growth not only reduced the initial resistance of the material but also provided an ideal interfacial barrier structure. Compared to the response of the pure Cu2O sensor, that of the Cu2O-MWCNT sensor to 1 ppm of H2S increased nearly 800 times at room temperature, and the response time decreased by more than 500 s. In addition to the excellent sensitivity with detection limits as low as 1 ppb, the Cu2O-MWCNT sensor was extremely selective with low-temperature adaptability. The sensor had a response value of 80.6 to 0.1 ppm of H2S at -10 °C, which is difficult to achieve with sensors based on oxygen adsorption/desorption mechanisms. The sensor was used for the detection of real oral exhaled breath, confirming its feasibility as a real-time disease monitoring sensor. The Cu2O-MWCNT heterostructures maximized the advantages of the individual components and laid the experimental foundation for future applications of highly sensitive portable breath analysis platforms for monitoring H2S.

Durian Shell-Mediated Simple Green Synthesis of Nanocopper against Plant Pathogenic Fungi

The synthesis of fungicides in eco-friendly and cost-effective ways is significantly essential for agriculture. Plant pathogenic fungi cause many ecological and economic issues worldwide, which must be treated with effective fungicides. Here, this study proposes the biosynthesis of fungicides, which combines copper and Cu₂O nanoparticles (Cu/Cu₂O) synthesized using durian shell (DS) extract as a reducing agent in aqueous media. Sugar and polyphenol compounds contained in DS, as the main phytochemicals acting in the reduction procedure, were extracted under different temperatures and duration conditions to obtain the highest yields. We confirmed the extraction process performed at 70 °C for 60 min to be the most effective in extracting sugar (6.1 g/L) and polyphenols (22.7 mg/L). We determined the suitable conditions for Cu/Cu₂O synthesis using a DS extract as a reducing agent for a synthesis time of 90 min, a volume ratio of DR extract/Cu²⁺ of 15:35, an initial pH solution of 10, a synthesis temperature of 70 °C, and a CuSO₄ concentration of 10 mM. The characterization results of as-prepared Cu/Cu₂O NP showed a highly crystalline structure of Cu₂O and Cu with sizes estimated in the range of 40-25 nm and 25-30 nm, respectively. Through in vitro experiments, the antifungal efficacy of Cu/Cu₂O against Corynespora cassiicola and Neoscytalidium dimidiatum was investigated by the inhibition zone. The green-synthesized Cu/Cu₂O nanocomposites, which are potential antifungals against plant pathogens, exhibited excellent antifungal efficacy against both Corynespora cassiicola (MIC = 0.25 g/L, the diameter of the inhibition zone was 22.00 ± 0.52 mm) and Neoscytalidium dimidiatum (MIC = 0.0625 g/L, the diameter of the inhibition zone was 18.00 ± 0.58 mm). Cu/Cu₂O nanocomosites prepared in this study could be a valuable suggestion for the control of plant pathogenic fungi affecting crop species globally.

Non-enzymatic electrochemical detection of creatinine based on a glassy carbon electrode modified with a Pd/Cu2O decorated polypyrrole (PPy) nanocomposite: an analytical approach

The major constraints of standard enzymatic biosensors are poor long-term storage stability and high cost. Hence, there is extensive research towards fabrication of reliable enzymeless biosensors based on nanomaterials. In this paper, we present the development of an enzymeless electrochemical biosensor for highly precise detection of creatinine. This involves the use of a simple yet effective alternative to the commonly utilized Pd/Cu₂O/PPy nanocomposite, which was characterized by different analytical methods. The present electrochemical sensor provides a wide detection range (0.1 to 150 μM), low detection limit (0.05 μM) and high sensitivity (0.207 μA), and is capable of detecting the creatinine level in human urine samples, which are inexpensive. The results are reproducible, and the sensor is stable. The sensor demonstrates good electrocatalytic activity and selectivity towards the detection of creatinine in the presence of various other similar biological entities. When compared to other existing counterparts, the electrocatalytic behaviour of the present sensor is comparable, if not better. So, the present electrochemical sensor for creatinine might be employed as a long-term diagnostic alternative.

A Ni-modified CuS-based self-supported electrocatalyst with nanobead-like porous morphology for efficient hydrogen production in basic media

The enhanced HER catalytic activity of a porous CuS-based catalyst, which was converted from Cu2O, is due to both increased surface porosity and intrinsic activity resulting from the synergy between Cu and Ni.

Enhanced catalytic reduction of p-nitrophenol and azo dyes on copper hexacyanoferrate nanospheres decorated copper foams

Catalytic reduction of nitroaromatic compounds using low-cost non-precious metal containing catalyst remains an essential topic in wastewater treatment. Herein, copper hexacyanoferrate nanospheres decorated copper foams (CF) were prepared by a facile method, and it was used as structured catalysts for the reduction of p-nitrophenol (p-NP) and azo dyes. The catalyst obtained by calcination at 200 °C shows the highest catalytic activity, with an almost complete reduction of p-NP within 3 min with a rate of 2.057 min^-1 at room temperature, and it exhibited excellent reusability in successive 6 cycles. The effects of temperature, initial concentration, pH, and flow rate on p-NP reduction were investigated. Moreover, the mechanistic investigation revealed that fast electron transfer ability and enhanced adsorption for p-NP contributed to its enhanced catalytic performances. This work put forward an efficient approach for the construction of structured catalysts with enhanced performance in catalytic reduction applications.

Nickel foam supported porous copper oxide catalysts with noble metal-like activity for aqueous phase reactions

Contiguous metal foams offer a multitude of advantages over conventional powders as supports for nanostructured heterogeneous catalysts; most critically a preformed 3-D porous framework ensuring full directional coverage of supported catalyst, and intrinsic ease of handling and recyclability. Nonetheless, metal foams remain comparatively underused in thermal catalysis compared to more conventional supports such as amorphous carbon, metal oxides, zeolites and more recently MOFs. Herein, we demonstrate a facile preparation of highly-reactive, robust, and easy to handle Ni foam-supported Cu-based metal catalysts. The highly sustainable synthesis requires no specialized equipment, no surfactants or additive redox reagents, uses water as solvent, and CuCl2(H2O)2 as precursor. The resulting material seeds as well-separated micro-crystalline Cu2(OH)3Cl evenly covering the Ni foam. Calcination above 400 °C transforms the Cu2(OH)3Cl to highly porous CuO. All materials display promising activity towards the reduction of 4-nitrophenol and methyl orange. Notably, our leading CuO-based material displays 4-nitrophenol reduction activity comparable with very reactive precious-metal based systems. Recyclability studies highlight the intrinsic ease of handling for the Ni foam support, and our results point to a very robust, highly recyclable catalyst system.

Facile Synthesis of Energetic Nanoparticles of Copper Azide with High Initiation Ability for Micro-Initiator Applications Using Layered Copper Hydroxide

Copper azide (CA) is one of the preferred primary explosives in the micro-initiating device, and it is of conducive significance to develop high-content CA-modified materials. In this work, we reported two types of CA composites with CA nanorods embedded in carbon nanosheets (CA/C) and CA distributed on salicylic acid (CA/SA) using layered copper hydroxide nanosheets intercalated with salicylic acid as the precursor. The detailed characterizations demonstrated that CA/C exhibits eximious electrostatic sensitivity (1.06 mJ) due to the inherent structural characteristics of CA/C such as the limitation of the free movement of CA by the layered structure and preeminent electrical conductivity of carbon nanosheets. Surprisingly, CA/C with nearly 1.0 mg in the miro-initiating device can reliably detonate Hexanitrohexaazaisowurtzitane (CL-20). CA/C exhibits extremely high CA content (93%), excellent ignition ability, and detonation ability, and its performance is superior to pure CA and most CA-modified materials reported previously. CA/SA also has an excellent detonation ability and its electrostatic sensitivity is as low as 0.92 mJ. These findings provide a new perspective for the development of high-performance primary explosives for the micro-initiating device.

Partial oxidation of methane to methanol on boron nitride at near critical acetonitrile

Direct catalytic conversion of methane to methanol with O₂ has been a fundamental challenge in unlocking abundant natural gas supplies. Metal-free methane conversion with 17% methanol yield based on the limiting reagent O₂ at 275 °C was achieved with near supercritical acetonitrile in the presence of boron nitride. Reaction temperature, catalyst loading, dwell time, methane–oxygen molar ratio, and solvent-oxygen molar ratios were identified as critical factors controlling methane activation and the methanol yield. Extension of the study to ethane (C2) showed moderate yields of methanol (3.6%) and ethanol (4.5%).

Mineral-modulated Co catalyst with enhanced adsorption and dissociation of BH4- for hydrogenation of p-nitrophenol to p-aminophenol

Slow adsorption and dissociation kinetics of NaBH₄ onto the catalyst surface limit the hydrogenation reduction of hazardous p-nitrophenol to worthy p-aminophenol. Herein, we design a mineral-modulated catalyst to facilitate the rate-limiting step. Carbon-coated etched attapulgite (EAtp@C) is obtained by HF treatment. Co/EAtp@C is fabricated via anchoring cobalt nanoparticles (CoNPs) on the carrier EAtp@C. Compared to pure Co, the anchored CoNPs are more electronegative and stable, which provides abundant and stable active sites and accelerates the BH₄^- adsorption and dissociation. Therefore, Co/EAtp@C leads to nearly 100% reduction of p-nitrophenol to p-aminophenol within 8 min and its apparent rate constant K_app (0.69 min^-1) is 4 times higher than that of pure Co. Thermodynamic calculations show a lower activation energy (37.92 kJ mol-1) of Co/EAtp@C catalyst than that of pure Co. Co/EAtp@C also shows magnetic separability and good stability by remaining 98.6% of catalytic conversion rate after six cycles. Significantly, we detect the active species Co-H, and reveal the electron transfer mechanism between catalysts, BH₄^-, and p-nitrophenol by electrochemical method. These results offer a fundamental insight into the catalytic mechanism of p-nitrophenol hydrogenation for rational design of efficient catalysts.

The Synthesis of h-BN-Modified Z-Scheme WO3/g-C3N4 Heterojunctions for Enhancing Visible Light Photocatalytic Degradation of Tetracycline Pollutants

The photocatalytic performance of common photocatalysts is limited by their low surface area, insufficient absorption of light energy, and fast photogenerated electron-hole recombination rate. The introduction of Z-scheme photocatalysts decorated with hexagonal boron nitride (h-BN) has already been confirmed to be an effective way to extend the surface area and increase the charge separation, thereby enhancing the photocatalytic performance. In this study, a hexagonal boron nitride (h-BN)-decorated WO₃/g-C₃N₄ heterojunction photocatalyst was successfully synthesized via an in situ method using tungstic acid, melamine, and hexagonal boron nitride as the precursors. The physical and chemical properties of the resulting samples were thoroughly characterized. The surface, morphological, and optical properties of the resulting materials were thoroughly characterized by XRD, XPS, SEM, TEM, UV-vis DRS, BET surface areas, PL, and ESR analysis. The WO₃/g-C₃N₄/BN composite exhibited a much higher photocatalytic activity for tetracycline degradation under visible light irradiation than pure g-C₃N₄, WO₃, and BN. The favorable photocatalytic activity of WO₃/g-C₃N₄/BN composites can be ascribed to the increased surface area and enhanced separation efficiency of photogenerated electron-hole pairs by adding h-BN nanosheets and forming the WO₃/g-C₃N₄ heterojunction. This work indicates that the WO₃/g-C₃N₄/BN photocatalyst is a promising material in wastewater treatment.

Construction of a Cu-Based Metal-Organic Framework by Employing a Mixed-Ligand Strategy and Its Facile Conversion into Nanofibrous CuO for Electrochemical Energy Storage Applications

Recently, metal-organic frameworks (MOFs) have been widely employed as a sacrificial template for the construction of nanostructured materials for a range of applications including energy storage. Herein, we report a facile mixed-ligand strategy for the synthesis of a Cu-MOF, [Cu₃(Azopy)₃(BTTC)₃(H₂O)₃·2H₂O]_n (where BTTC = 1,2,4,5-benzenetetracarboxylic acid and Azopy = 4,4'-azopyridine), via a slow-diffusion method at room temperature. X-ray analysis authenticates the two-dimensional (2D)-layered framework of Cu-MOF. Topologically, this 2D-layered structure is assigned as a 4-connected unimodal net with sql topology. Further, nanostructured CuO is obtained via a simple precipitation method by employing Cu-MOF as a precursor. After analysis of their physicochemical properties through various techniques, both materials are used as surface modifiers of glassy carbon electrodes for a comparative electrochemical study. The results reveal a superior charge storage performance of CuO (244.2 F g^-1 at a current density of 0.8 A g^-1) with a high rate capability compared to Cu-MOF. This observation paves the pathway for the strategic design of high-performing supercapacitor electrode materials.

Simple borophosphate glasses for on-demand growth of self-supported copper nanoparticles in the reduction of 4-nitrophenol

Herein, we demonstrate a single-step synthesis of simple copper-doped borophosphate glasses and their unusual use for catalytic reduction of nitro groups from the aromatic nitro compounds. The copper-doped glasses were evaluated as an affordable heterogeneous catalytic glass-based material for the reduction of 4-nitrophenol by sodium borohydride. The glass matrix acts as a host and support material for in situ self-growth of zero-valent copper (Cu) nanoparticles (NPs) on the glass surface. Thus, zero-valent CuNPs are produced in situ on the glass surface that is accomplished by the interaction of copper ions with hydride ions. Using an intrinsic reaction kinetic constant, we find a catalytic activity of 0.144 L s^-1 g^-1 for a glass-based catalyst doped with a non-noble metal, which is an order of magnitude higher when compared to the values observed elsewhere. Furthermore, the reuse of glass catalyst after six successive cycles demonstrates an outstanding performance compared to that of the parent material. A mathematical model based on the Langmuir-Hinshelwood mechanism related to an empirical growth rate of the zero-valent CuNPs was proposed to describe the kinetic of the 4-nitrophenol catalytic hydrogenation.

A facile approach to synthesize CdS-attapulgite as a photocatalyst for reduction reactions in water

At room temperature, a facile approach has been utilized for preparing novel CdS–attapulgite (CdS–ATP) composites and the composites were applied in photocatalytic reduction of p-nitrophenol and Cr(vi). The effect of ATP on the photocatalytic activity of the CdS–ATP composites were studied by controlling the mass ratio of attapulgite. The results showed that the CdS–20%ATP composite has an excellent photocatalytic activity. In order to figure out the key to improve the photocatalytic efficiency, the prepared composites were characterized by Brunauer–Emmett–Teller (BET) specific surface area, UV-vis diffuse reflectance spectroscopy (DRS) and electrochemical impedance spectroscopy (EIS). The superior photocatalytic performance of the CdS–20%ATP composite can be ascribed to the existence of the ATP which can fix the CdS and prevent agglomeration. The interaction between ATP and CdS in the composites facilitates the electron transfer and also promoted their photocatalytic performance. This work provides us with some significant guidance in the development of CdS–ATP composite photocatalysts.

The application of CdS–attapulgite composites in photocatalytic reduction of p-nitrophenol and Cr(vi) demonstrated that the attapulgite could overcome the limitations of CdS.

Self-Circulation Oxygen-Hydrogen Peroxide-Oxygen System for Ultrasensitive Cathode Photoelectrochemical Bioassay Using a Stacked Sealed Paper Device

In this work, a self-circulation oxygen-hydrogen peroxide-oxygen (O₂-H₂O₂-O₂) system with photogenerated electrons as fuel and highly active hemin monomers as operators was engineered for ultrasensitive cathode photoelectrochemical bioassay of microRNA-141 (miRNA-141) using a stacked sealed paper device. During the circulation, the photogenerated electrons from BiVO₄/Cu₂O photosensitive structures assembled on a reduced graphene oxide paper electrode first reduced the electron acceptors (dissolved O₂) to H₂O₂, which was then catalytically decomposed by hemin monomers to generate O₂ again. The regenerated O₂ continued to be reduced, which made O₂ and H₂O₂ stuck in the infinite loop of O₂-H₂O₂-O₂ accompanied by the fast consumption of photogenerated electrons, generating an amplified photocurrent signal. When a target existed, a duplex-specific nuclease-induced target recycling reaction with dual trigger DNA probes as the output was performed to initiate the assembly of bridge-like DNA nanostructures, which endowed the self-circulation system with dual destruction functions as follows. (i) Reduced fuel supply: the assembled DNA bridges acting as a negatively charged barrier prevented the photogenerated electrons from participating in the O₂ reduction to H₂O₂. (ii) Incapacitation of operators: DNA bridging induced the dimerization of hemin monomers linked on the DNA hairpins to catalytically inactive hemin dimers, leading to the abortive regeneration of O₂. These destruction functions resulted in the circulation interruption and a remarkably decreased photocurrent signal. Thus, the developed cathode photoelectrochemical biosensing platform achieved ultrasensitive miRNA-141 detection with a linear range of 0.25 fM to 1 nM and a detection limit of 83 aM, and it also exhibited high accuracy, selectivity, and practicability.

Nitrogen-doped porous carbon-encapsulated copper composite for efficient reduction of 4-nitrophenol

Developing low-cost non-precious metals as efficient catalysts for the reduction of toxic 4-nitrophenol (4-NP) to useful 4-aminophenol (4-AP) have received increasing attention in recent years. Herein, a novel and efficient Cu-based catalyst Cu/Cu_xO@CN (carbon doped with nitrogen) was prepared via a facile method from pyrolysis of bi-ligand MOFs material Cu₂(BDC)₂(BPY) (BDC = p-Phthalic acid, BPY = 4,4'-bipyridyl) in Ar atmosphere. Characterization results revealed that N doping in carbon matrix favors the development of mesoporous structure, the formation of more defect sites in carbon matrix, better dispersion of Cu/Cu_xO nano particles, and maintenance of Cu species in metallic Cu state (the active site), all of which contribute to a superior catalytic activity for 4-NP reduction with a pseudo-first-order rate constant as high as 0.126 s^-1 (the molar ratio of NaBH₄ to 4-NP is 400), nearly 11 times higher than its counterpart Cu/Cu_xO@C without N doping (0.011 s^-1). The activation energy for 4-NP reduction to 4-AP catalyzed by Cu/Cu_xO@CN was determined as 55.6 kJ mol^-1 (the molar ratio of NaBH₄ to 4-NP is 100). In addition, Cu/Cu_xO@CN showed excellent reusability in successive 6 cycles. The facile synthesis and superior catalytic activity make Cu/Cu_xO@CN a promising catalyst in industrial applications for many other similar reaction systems.

Novel porous ceramic sheet supported metal reactors for continuous-flow catalysis

A novel porous ceramic sheet supported nickel particles reactor was obtained by an in-situ preparation method. This reactor was then used to investigate continuous-flow catalysis of nitroaromatic compounds and methyl orange. The details of the structure and morphology were characterized by XRD, SEM, XPS, Raman, element mapping, mercury intrusion method and Archimedes principle. The porous ceramic sheet supported Ni particles reactor exhibited excellent catalytic performance in the catalytic reduction of p-nitrophenol and methyl orange by sodium borohydride at room temperature. Both the conversion of p-nitrophenol (5 mM) and methyl orange (0.3 mM) reached nearly 100% at the injection speed of 2.67 mL·min^-1. In addition, it maintained conversions of 100% after 10 recycling time since the porous ceramic sheet could reduce the aggregation for Ni particles. Furthermore, the chemisorbed oxygen, and the strong interaction between Ni and porous ceramic sheet resulted in a highly efficient, recoverable, and cost-effective multifunctional reactor. All of these advantages present new opportunities to be implemented in the field of waste water treatment and environmental toxicology. Ultimately, the porous ceramic sheet could also support other metal nanomaterial, and used in other fields of environmental catalysis.

Strong interaction between Au nanoparticles and porous polyurethane sponge enables efficient environmental catalysis with high reusability

A novel and recoverable platform of polyurethane (PU) sponge-supported Au nanoparticle catalyst was obtained by a water-based in-situ preparation process. The structure, chemical, and morphology properties of this platform were characterized by XRD, TGA, SEM, FT-IR, and XPS. The Au/PU sponge platform exhibited excellent catalytic performances in catalytic reductions of p-nitrophenol and o-nitroaniline at room temperature, and both catalytic reactions could be completed within 4.5 and 1.5 min, respectively. Furthermore, the strong interaction between Au nanoparticles and the PU sponge enabled the catalyst system to maintain a high catalytic efficiency after 5 recycling times, since the PU sponge reduced the trend of leaching and aggregation of Au nanoparticles. The unique nature of Au nanoparticles and the porous PU sponge along with their strong interaction resulted in a highly efficient, recoverable, and cost-effective multifunctional catalyst. The AuNP/Sponge nanocatalyst platform has great potential for wide environmental and other catalytic applications.

The Properties and Preparation Methods of Different Boron Nitride Nanostructures and Applications of Related Nanocomposites

Due to special non-metallic polar bond between the III group (with certain metallic properties) element boron (B) and the V group element nitrogen (N), boron nitride (BN) has unique physical and chemical properties such as strong high-temperature resistance, oxidation resistance, heat conduction, electrical insulation and neutron absorption. Its unique lamellar, reticular and tubular morphologies and physicochemical properties make it attractive in the fields of adsorption, catalysis, hydrogen storage, thermal conduction, insulation, dielectric substrate of electronic devices, radiation protection, polymer composites, medicine, etc. Therefore, the synthesis and properties of BN derived materials become the main research hotspots of low-dimensional nanomaterials. This paper reviews the synthetic methods, overall properties, and applications of BN nanostructures and nanocomposites. In addition, challenges and prospect of this kind of materials are discussed.

Highly efficient degradation of iohexol on a heterostructured graphene-analogue boron nitride coupled Bi2MoO6 photocatalyst under simulated sunlight

Iohexol (IOH), as a typical iodinated X-ray contrast media (ICMs) with potential threat to human health, is difficult to be removed with the conventional wastewater treatment methods. In this work, new boron nitride coupled Bi₂MoO₆ layered microspheres (BN/Bi₂MoO₆) composites were applied to remove IOH from water via photocatalytic degradation. The degradation constant k_app of IOH over 3.5 wt% BN/Bi₂MoO₆ was 0.016 min^-1, which was 3.2 times that of Bi₂MoO₆ (0.005 min^-1). The degradation rate of IOH on 3.5 wt% BN/Bi₂MoO₆ reached 92% in 150 min. The enhanced photocatalytic activity of BN/Bi₂MoO₆ can be attributed to the heterojunction between BN and Bi₂MoO₆. The matched type-I band alignment heterojunction of two semiconductors prominently improved the charge separation. Based on the trapping experiments, holes and superoxide radicals were proved to be the main active species for photocatalytic IOH degradation. Besides, the degradation products of IOH were analyzed by LC-HRMS and the possible degradation mechanism of IOH was also proposed in this work.