Monodisperse Cu/Cu2O@C core-shell nanocomposite supported on rGO layers as an efficient catalyst derived from a Cu-based MOF/GO structure

Multi-functional copper oxide nanoparticles synthesized using Lagerstroemia indica leaf extracts and their applications

Developing multifunctional nanomaterials through environmentally friendly and efficient approaches is a pivotal focus in nanotechnology. This study aimed to employ a biogenic method to synthesize multifunctional copper oxide nanoparticles (LI-CuO NPs) with diverse capabilities, including antibacterial, antioxidant, and seed priming properties, as well as photocatalytic organic dye degradation and wastewater treatment potentials using Lagerstroemia indica leaf extract. The synthesized LI-CuO NPs were extensively characterized using UV-vis spectroscopy, dynamic light scattering (DLS), X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform-infrared spectroscopy (FT-IR). The colloid displayed surface plasmon resonance peaks at 320 nm, characteristic of LI-CuO NPs. DLS analysis revealed an average particle size of 93.5 nm and a negative zeta potential of -20.3 mV. FTIR and XPS analyses demonstrated that LI-CuO NPs possessed abundant functional groups that acted as stabilizing agents. XRD analysis indicated pure crystalline and spherical LI-CuO NPs measuring 36 nm in size. Antibacterial tests exhibited significant differential activity of LI-CuO NPs against both gram-negative (Escherichia coli, Salmonella typhimurium) and gram-positive (Staphylococcus aureus and Listeria monocytogenes) bacteria. In antioxidant tests, the LI-CuO NPs demonstrated a remarkable radical scavenging activity of 97.6 % at a concentration of 400 μg mL-1. These nanoparticles were also found to enhance mustard seed germination at low concentrations. With a remarkable reusability, LI-CuO NPs exhibited excellent photocatalytic performance, with a degradation efficiency of 97.6 % at 150 μg/mL as well as a 95.6 % reduction in turbidity when applied to wastewater treatment. In conclusion, this study presents environmentally friendly method for the facile synthesis of LI-CuO NPs that could potentially offer promising applications in biomedicine, agriculture, and environmental remediation due to their multifunctional properties.

Solid-State Synthesis of Liquorice-Stabilized Copper-Based Nanoparticles: Structural and Catalytic Studies

A large-scale quantity of copper oxalate nanoparticles were successfully obtained via a facile and green solid-state chemical reaction. Copper oxalate nanoparticles were obtained by ball-milling between copper chloride, Liquorice (Glycyrrhiza glabra), and ascorbic acid at ambient conditions. The size and morphology of copper oxalate nanoparticles powder were studied by transmission and scanning electron microscopy. The prepared nanoparticles were semi-spherical in shape and ranged from 5 to 15 nm in size. UV/Vis spectroscopy, Fourier transforms infrared spectroscopy, and X-ray photoelectron spectroscopy measurements were carried out to characterize the prepared samples. Copper oxalate nanoparticles were evaluated as a catalyst in the catalytic degradation of 4-nitrophenol, bromophenol blue, reactive yellow, and a mixture of the three pollutants. The present study combined solid-state reaction and green requirements for the mass production of nanomaterials. The proposed reaction is performed in simple steps, inexpensive, low energy consuming, solvent-free, and minimizes the emission of secondary wastes.

Copper oxides supported sulfur-doped porous carbon material as a remarkable catalyst for reduction of aromatic nitro compounds

Synthesis and manufacturing of metal-organic framework derived carbon/metal oxide nanomaterials with an advisable porous structure and composition are essential as catalysts in various organic transformation processes for the preparation of environmentally friendly catalysts. In this work, we report a scalable synthesis of sulfur-doped porous carbon-containing copper oxide nanoparticles (marked CuxO@CS-400) via direct pyrolysis of a mixture of metal-organic framework precursor called HKUST-1 and diphenyl disulfide for aromatic nitro compounds reduction. X-ray diffraction, surface area analysis (BET), X-ray energy diffraction (EDX) spectroscopy, thermal gravimetric analysis, elemental mapping, infrared spectroscopy (FT-IR), transmission electron microscope, and scanning electron microscope (FE-SEM) analysis were accomplished to acknowledge and investigate the effect of S and CuxO as active sites in heterogeneous catalyst to perform the reduction-nitro aromatic compounds reaction in the presence of CuxO@CS-400 as an effective heterogeneous catalyst. The studies showed that doping sulfur in the resulting carbon/metal oxide substrate increased the catalytic activity compared to the material without sulfur doping.

Hollow MIL-125 Nanoparticles Loading Doxorubicin Prodrug and 3-Methyladenine for Reversal of Tumor Multidrug Resistance

Multidrug resistance (MDR) is a key factor in chemotherapy failure and tumor recurrence. The inhibition of drug efflux and autophagy play important roles in MDR therapy. Herein, a multifunctional delivery system (HA-MIL-125@DVMA) was prepared for synergistically reverse tumor MDR. Tumor-targeted hollow MIL-125-Ti nanoparticles were used to load the doxorubicin-vitamin E succinate (DV) prodrug and 3-methyladenine (3-MA) to enhance reverse MDR effects. The pH-sensitive DV can kill tumor cells and inhibit P-gp-mediated drug efflux, and 3-MA can inhibit autophagy. HA-MIL-125@DVMA had uniformly distributed particle size and high drug-load content. The nanoparticles could effectively release the drugs into tumor microenvironment due to the rapid hydrazone bond-breaking under low pH conditions, resulting in a high cumulative release rate. In in vitro cellular experiments, the accumulation of HA-MIL-125@DVMA and HA-MIL-125@DV in MCF-7/ADR cells was significantly higher than that in the control groups. Moreover, the nanoparticles significantly inhibited drug efflux in the cells, ensuring the accumulation of the drugs in cell cytoplasm and causing drug-resistant cells' death. Importantly, HA-MIL-125@DVMA effectively inhibited tumor growth without changes in body weight in tumor-bearing mice. In summary, the combination of the acid-sensitive prodrug DV and autophagy inhibitor 3-MA in a HA-MIL-125 nanocarrier can enhance the antitumor effect and reverse tumor MDR.

Opportunities from Metal Organic Frameworks to Develop Porous Carbons Catalysts Involved in Fine Chemical Synthesis

In the last decade, MOFs have been proposed as precursors of functional porous carbons with enhanced catalytic performances by comparison with other traditional carbonaceous catalysts. This area is rapidly growing mainly because of the great structural diversity of MOFs offering almost infinite possibilities. MOFs can be considered as ideal platforms to prepare porous carbons with highly dispersed metallic species or even single-metal atoms under strictly controlled thermal conditions. This review briefly summarizes synthetic strategies to prepare MOFs and MOF-derived porous carbons. The main focus relies on the application of the MOF-derived porous carbons to fine chemical synthesis. Among the most explored reactions, the oxidation and reduction reactions are highlighted, although some examples of coupling and multicomponent reactions are also presented. However, the application of this type of catalyst in the green synthesis of biologically active heterocyclic compounds through cascade reactions is still a challenge.

Graphene-Based Metal-Organic Framework Hybrids for Applications in Catalysis, Environmental, and Energy Technologies

Current energy and environmental challenges demand the development and design of multifunctional porous materials with tunable properties for catalysis, water purification, and energy conversion and storage. Because of their amenability to de novo reticular chemistry, metal-organic frameworks (MOFs) have become key materials in this area. However, their usefulness is often limited by low chemical stability, conductivity and inappropriate pore sizes. Conductive two-dimensional (2D) materials with robust structural skeletons and/or functionalized surfaces can form stabilizing interactions with MOF components, enabling the fabrication of MOF nanocomposites with tunable pore characteristics. Graphene and its functional derivatives are the largest class of 2D materials and possess remarkable compositional versatility, structural diversity, and controllable surface chemistry. Here, we critically review current knowledge concerning the growth, structure, and properties of graphene derivatives, MOFs, and their graphene@MOF composites as well as the associated structure-property-performance relationships. Synthetic strategies for preparing graphene@MOF composites and tuning their properties are also comprehensively reviewed together with their applications in gas storage/separation, water purification, catalysis (organo-, electro-, and photocatalysis), and electrochemical energy storage and conversion. Current challenges in the development of graphene@MOF hybrids and their practical applications are addressed, revealing areas for future investigation. We hope that this review will inspire further exploration of new graphene@MOF hybrids for energy, electronic, biomedical, and photocatalysis applications as well as studies on previously unreported properties of known hybrids to reveal potential "diamonds in the rough".

Preparation of an electrochemical immunosensor based on a Cu/Cu2O-rGO@Au signal synergistic amplification strategy and efficient and sensitive detection of alpha-fetoprotein

The effective amplification of the signal is the prerequisite for the ultrasensitive detection of electrochemical immunosensors. To quantitatively detect alpha-fetoprotein (AFP), we prepared a sandwich-type electrochemical immunosensor. Using a gold nanoparticles (Au NPs) modified glassy carbon electrode (GCE) as the sensing platform and Cu/Cu₂O-rGO@Au as the signal label, differential pulse voltammetry (DPV) was used to achieve sensitive detection of AFP. We found that the nanomaterials can undergo electro-oxidation and electro-reduction reactions between Cu(I) and Cu(II) in a buffer solution of pH = 6.0. It is worth mentioning that the incorporation of metals into metal oxide substrates is a new strategy to combine the catalytic activity of metal oxides with the electrical conductivity of metals. Reduced graphene oxide (rGO), which is rich in oxygen-containing groups, can load more Cu/Cu₂O and Au NPs and increase the conductivity. The modification of Au NPs makes them have better biocompatibility and conductivity. Under the best detection conditions, the prepared immunosensor realizes the specific and ultrasensitive detection of AFP. The detection range is 0.01-50 ng mL^-1 and the limit of detection (LOD) was as low as 0.589 pg mL^-1 (S/N = 3); meanwhile it also has good practical application ability. Therefore, this immunosensor provides an important means for the early screening and detection of AFP.

Efficient Suzuki-Miyaura cross-coupling reaction by loading trace Pd nanoparticles onto copper-complex-derived Cu/C-700 solid support

The development of efficient carbon-carbon cross-coupling catalysts with low noble metal amounts attracts much attention recently. Herein, a Cu/C-700/Pd nanocomposite is obtained by loading trace Pd²⁺ onto carbon support derived from a novel mononuclear copper complex, {[Cu(POP)₂(Phen)₂]BF₄}. The as-prepared nanomaterial features the facial structure of highly dispersed copper phosphide nanoparticles as well as Pd nanoparticles via neighboring Cu-Pd sites. The Cu/C-700/Pd nanocomposite shows excellent catalytic activity (99.73%) and selectivity in Suzuki-Miyaura cross-coupling reaction, at trace Pd loading (0.43 mol%). Compared with the reported palladium nano catalysts, its advantages are proved. The appealing gateway to this stable, innovative and recyclability, Cu/C-700/Pd nanostructure recommends its beneficial utilization in carbon-carbon coupling and other environmentally friendly processes.

Pyrolysis of a metal-organic framework followed by in situ X-ray absorption spectroscopy, powder diffraction and pair distribution function analysis

Metal-organic frameworks (MOFs) can serve as precursors for new nanomaterials via thermal decomposition. Such MOF-derived nanomaterials (MDNs) are often comprised of metal and/or metal oxide particles embedded on porous carbon....

Novel bimetallic MOF derived N-doped carbon supported Ru nanoparticles for efficient reduction of nitro aromatic compounds and rhodamine B

N-doped carbon enables Ru-NC-15 to exhibit extremely high catalytic activity towards 4-nitrophenol and rhodamine B reduction.

Cu/Cux S-Embedded N,S-Doped Porous Carbon Derived in Situ from a MOF Designed for Efficient Catalysis

The reasonable design of the precursor of a carbon-based nanocatalyst is an important pathway to improve catalytic performance. In this study, a simple solvothermal method was used to synthesize [Cu(TPT)(2,5-tdc)] ⋅ 2H₂ O (Cu-MOF), which contains N and S atoms, in one step. Further in-situ carbonization of the Cu-MOF as the precursor was used to synthesize Cu/Cu_x S-embedded N,S-doped porous carbon (Cu/Cu_x S/NSC) composites. The catalytic activities of the prepared Cu/Cu_x S/NSC were investigated through catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The results show that the designed Cu/Cu_x S/NSC has exceptional catalytic activity and recycling stability, with a reaction rate constant of 0.0256 s^-1 , and the conversion rate still exceeds 90 % after 15 cycles. Meanwhile, the efficient catalytic reduction of dyes (CR, MO, MB and RhB) confirmed its versatility. Finally, the active sites of the Cu/Cu_x S/NSC catalysts were analyzed, and a possible multicomponent synergistic catalytic mechanism was proposed.

Decorating graphene oxide with zeolitic imidazolate framework (ZIF-8) and pseudo-boehmite offers ultra-high adsorption capacity of diclofenac in hospital effluents

This study reports on an easy and scalable synthesis method of a novel magnetic nanocomposite (GO/ZIF-8/γ-AlOOH) based on graphene oxide (GO) nanosheets decorated with zeolitic imidazolate framework-8 (ZIF-8), pseudo-boehmite (γ-AlOOH), and iron oxide (Fe₃O₄) nanoparticles by combining solvothermal and solid-state dispersion (SSD) methods. The nanocomposite was successfully applied to remove of diclofenac sodium (DCF) - a widely used pharmaceutical - from water. Response Surface Methodology (RSM) was used to optimize the adsorption process and assess the interactions among the influencing factors on DCF removal efficiency; including contact time, adsorbent dosage, initial pH, solution temperature, and DCF concentration. Adsorption isotherm results showed a good fitting with the Langmuir isotherm model with an exceptional adsorption capacity value of 2594 mg g^-1 at 30 °C, which was highly superior to the previously reported adsorbents. In addition, kinetic and thermodynamic investigations further illustrated that the adsorption process was fast (equilibrium time = 50 min) and endothermic. The regeneration of GO/ZIF-8/γ-AlOOH nanocomposite using acetic acid solution (10% v/v) after a simple magnetic separation was confirmed in five consecutive cycles, which eliminate the usage of organic solvents. The nanocomposite has also shown a superior performance in treating a simulated hospital effluent that contained various pharmaceuticals as well as other organic, and inorganic constituents.

Recent advances on preparation and environmental applications of MOF-derived carbons in catalysis

Carbon materials derived from metal organic frameworks (MOFs) have excellent properties of high surface area, high porosity, adjustable pore size, high conductivity and stability, and their applications in catalysis have become a rapidly expanding research field. In this review, we have summarized the synthesis strategies of MOF-derived carbons with different physical and chemical properties, obtained through direct carbonization, co-pyrolysis and post-treatment. The potential applications of derived carbons, especially monometal-, bimetal-, nonmetal-doped and metal-free carbons in organo-catalysis, photocatalysis and electrocatalysis are analyzed in detail from the environmental perspective. In addition, the improvement of catalytic efficiency is also considered from the aspects of increasing active sites, enhancing the activity of reactants and promoting free electron transfer. The function and synergy of various species of the composites in the catalytic reaction are summarized. The reaction paths and mechanisms are analyzed, and research ideas or trends are proposed for further development.

Vapor-assisted self-conversion of basic carbonates in metal-organic frameworks

Incorporation of nanoparticles has been considered as an efficient method for enhancing the adsorption performance of metal-organic frameworks (MOFs). Alkali metal compounds possess outstanding affinity to acidic CO2. In this study, a robust self-conversion strategy is reported for improving the carbon capture performance of MOFs, through directly transforming partial metal centers to basic carbonate (BC) nanoparticles. Based on the hydrolysis of coordination bonds induced by water impurity in solvents and the decarboxylation of linkers under thermal and alkaline conditions, the self-loading of BC in MOFs can be realized by solvent vapor-assisted thermal treatment. Since water impurity causes limited self-conversion and excess organic solvent can purify MOFs, the BC-MOF materials maintain good crystallinity and even show superior porosity. Owing to the increased specific surface areas, open metal sites, and alkalinity of BC, the prepared MOF composites exhibit substantially improved CO2 capture performance with good balance between capacity and selectivity. For example, after self-conversion with ethanol solvent, the CO2 adsorption capacity and CO2/N2 (15 : 85) selectivity at 298 K and 100 kPa increase from 3.7 mmol g-1 and 11.4 to 5.8 mmol g-1 and 29.2, respectively.

Photoinduced In Situ Spontaneous Formation of a Reduced Graphene Oxide-Enwrapped Cu-Cu2O Nanocomposite for Solar Hydrogen Evolution

The fast recombination of photogenerated charge carriers and poor stability have impeded the application of many narrow band gap semiconductors with otherwise excellent photocatalytic performance. A metal-semiconductor Schottky junction is a promising strategy to accelerate charge separation and enhance catalytic efficiency. However, the preparation of these structures often involves intricate processes and harsh conditions, which will inevitably destroy the electronic structures of the semiconductors and ruin their original properties in practical applications. In this study, a reduced graphene oxide (RGO)-enwrapped Cu-Cu₂O nanocomposite (Cu-Cu₂O@RGO) spontaneously evolved from an aqueous alcoholic solution containing cupric ions and graphene oxide (GO) under simulated sunlight irradiation. During this process, GO reduction and Cu-Cu₂O nanoparticles growth occurred simultaneously in conjunction with in situ RGO encapsulation. Benefiting from the superior intrinsic semiconductor characteristic retention under mild reaction conditions, strong component interactions, and efficient interfacial charge transfer, the distinctive Cu-Cu₂O@RGO nanocomposite supplied multiple channels for rapid electron transfer to substantially enhance the charge carrier separation efficiency and provide perfect chemical protection to effectively prevent Cu₂O photocorrosion. This product also greatly suppressed self-aggregation to decrease the size of nanoparticles. Based on these merits, the Cu-Cu₂O@RGO nanocomposite offered promising advances in photoelectrochemical and photocatalytic H₂ evolution. This work provides an innovative photoinduced strategy for constructing an RGO-enwrapped semiconductor nanocomposite with efficient charge transfer interfaces while providing novel insights for the efficient solar energy utilization.

Metal–organic framework (MOF)-derived catalysts for chemoselective hydrogenation of nitroarenes

The MOFs derived catalysts conducted in the chemoselective hydrogenation of substituted nitroarenes, including pyrolysis and confined catalyst, are reviewed.

A facile template method to fabricate one-dimensional Fe3O4@SiO2@C/Ni microtubes with efficient catalytic and adsorption performance

The Fe3O4@SiO2@C/Ni microtubes were well constructed with MoO3 microrods as sacrificing template, which manifested excellent performance as both catalyst and adsorbent.

Fabrication of Few-Layer Graphene-Supported Copper Catalysts Using a Lithium-Promoted Thermal Exfoliation Method for Methanol Oxidative Carbonylation

Exfoliation of graphene oxide (GO) via thermal expansion is regarded as the most promising approach to obtain few-layer graphene (FLG) in bulk. Herein, we introduce an efficient strategy for improving the exfoliation process by adding a tiny amount of lithium nitrate in the precursors, which significantly enhances the removal of oxygen-containing functional groups and produces 1-2 layer graphene. FLG-supported highly dispersed Cu nanoparticles (NPs, ≈4.2 nm) can be further synthesized through exfoliating the mixture of GO, lithium nitrate, and copper(II) nitrate, which displayed superior catalytic activity and stability in the synthesis of dimethyl carbonate (DMC) using liquid methanol oxidative carbonylation. The characterization results demonstrate that during the thermal expansion process, lithium nitrate was decomposed to Li₂O and immediately reacted with CO₂ released by the decomposition of GO to form stable Li₂CO₃, which promotes efficient charge transfer and produces Cu^δ+ (0 < δ < 1) species in the Cu/Li-PGO catalyst. Density functional theory calculations prove that the presence of Cu^δ+ markedly facilitates CO adsorption over the resulting catalyst and causes a decrease of the energy barrier of the rate-limiting step for DMC formation (CO insertion). These findings give a theoretical explanation of the enhanced catalytic performance of the Cu/Li-PGO catalyst. The present work provides a simple and practical avenue to the exfoliation of graphene and the dispersions of metal NPs on graphene sheets.

Heterogeneous Electro-Fenton catalysis with HKUST-1-derived Cu@C decorated in 3D graphene network

Transition metal and nanocarbon-based composites with high activity and stability draw great attention in electro-Fenton system for organic pollutants removal. In this study, HKUST-1-derived Cu@C nanoparticles embedded within three-dimensional reduced graphene oxide (rGO) network (denoted as 3DG/Cu@C) is synthesized through a simple strategy. The prepared catalyst shows ordered 3D porous carbon structure and Cu@C NPs are uniformly dispersed in the matrix. The 3DG/Cu@C is used as heterogeneous electro-Fenton (hetero-EF) catalyst and shows outstanding performance in various persistent organic pollutants removal. High concentration Rhodamine B (RhB) (40 mg L^-1) can achieve a complete decolorization within 150 min with 25 mg L^-1 3DG/Cu@C catalyst, which is one of the lowest catalyst dosages in hetero-EF for RhB removal. More importantly, the 3DG/Cu@C achieves high RhB mineralization efficiency of 81.5% and exhibits high catalytic performance in a wide pH window from 3 to 9. The 3DG/Cu@C also remains high efficiency after five successive reaction cycles. The working mechanism study shows that RhB is mainly oxidized by ^•OH and O₂^•- radicals through hetero-EF and anodic oxidation processes. The high stability and outstanding performance of 3DG/Cu@C provide new insights in organic pollutants removal by hetero-EF process with transition metal and nanocarbon-based catalysts.

Rare Earth Oxide Anchored Platinum Catalytic Site Coated Zeolitic Imidazolate Frameworks toward Enhancing Selective Hydrogenation

Controlling and manipulating the self-assembly technology at the nanoscale has become a powerful strategy for improving chemical processes and further developing the conception of atom efficiency. Herein, an unexpected core-shell structured Gd₂O₃@Pt@ZIF-8 nanoreactor has been fabricated using the self-assembly strategy in which the firm Gd₂O₃ nanosupport anchored the highly active Pt nanoparticle coated porous zeolitic imidazolate framework (ZIF-8). The well-designed Gd₂O₃@Pt@ZIF-8 structure shows good performance in selective hydrogenation of aldehyde-, keto-, and nitro-compounds with full conversion (>99.9%) and superior selectivity (>95%). It showed the channel sieving effect of the ZIF-8 channels toward enhancing the catalytic selectivity. After being recycled eight times, their activity remains unchanged and their core-shell structure is kept intact. So, the outer ZIF-8 membranes not only prevent Pt nanoparticles from agglomeration and slipping during a catalytic reaction but also maintain the original activity and long-term stability compared to the Gd₂O₃@Pt catalyst. The self-assembly strategy demonstrated here will allow the development of other highly active, stable, and selective catalysts for important but challenging transformations.

The first ternary Nd-MOF/GO/Fe3O4 nanocomposite exhibiting an excellent photocatalytic performance for dye degradation

A ternary Nd-MOF/GO/Fe₃O₄ nanocomposite was prepared as a recyclable photocatalyst for the photocatalytic degradation of MB and showed excellent stability.

pH-Controllable regeneration and visible-light photocatalytic redox of carbon and nitrogen co-doped Zn3Nb2O8 towards degradation of multiple contaminants

N/C–Zn₃Nb₂O₈ with a compatible band structure and negative surface demonstrates enhanced visible light photocatalytic activity and stability in degradation of multiple pH-sensitive contaminants.

Synthesis and controlled morphology of Ni@Ag core shell nanowires with excellent catalytic efficiency and recyclability

Ni@Ag core shell nanowires (NWs) were prepared by in situ chemical reduction of Ag⁺ around NiNWs as the inner core. Different Ni@Ag NWs with controllable morphologies were achieved through the layer-plus-island growth mode and this mechanism was confirmed by scanning electron microscopy, X-ray fluorescence, and X-ray photoelectron spectroscopy analyses. When used as a catalyst, the synthesized Ni@Ag NWs exhibited high reduction efficiency by showing a high reaction rate constant k of 0.408 s^-1 in reducing 4-nitrophenol at room temperature. Besides, combining the magnetic property, including high saturation magnetization and low coercivity, the magnetic NiNW core contributes to excellent recyclability and long-term stability with only a 2.2% performance loss after 10 recycles by magnets. The Ni@Ag NWs proposed here show unprecedentedly high potential in applications requiring high efficiency and a recyclable catalyst.

In situ growth of ZIF-8-derived ternary ZnO/ZnCo2O4/NiO for high performance asymmetric supercapacitors

In this paper, the rational design and synthesis of ZIF-8-derived ternary ZnO/ZnCo₂O₄/NiO wrapped by nanosheets is introduced. Polyhedral ternary ZnO/ZnCo₂O₄/NiO composites surrounded by nanosheets with different compositions are successfully fabricated through in situ growth on ZIF-8 templates and subsequent thermal annealing in air. Electrochemical investigation reveals that when the molar ratio of nickel nitrate to cobalt nitrate is 1, the composite material is more outstanding, which shows a high specific capacitance of 1136.4 F g^-1 at 1 A g^-1 and excellent cycling stability of 86.54% after 5000 cycles. Moreover, the excellent performance of this material is also confirmed by assembling an asymmetric supercapacitor. The assembled hybrid device can reach a large potential range of 0-1.6 V and deliver a high energy density of 46.04 W h kg^-1 as well as the maximum power density of 7987.5 W kg^-1.

Bimetallic cerium and ferric oxides nanoparticles embedded within mesoporous carbon matrix: Electrochemical immunosensor for sensitive detection of carbohydrate antigen 19-9

A label-free electrochemical immunosensor was successfully developed for sensitively detecting carbohydrate antigen 19-9 (CA19-9) as a cancer marker. To achieve this, a series of bimetallic cerium and ferric oxide nanoparticles embedded within the mesoporous carbon matrix (represented by CeO₂/FeO_x@mC) was obtained from the bimetallic CeFe-based metal organic framework (CeFe-MOF) by calcination at different high temperatures. The formed CeO₂ or FeO_x nanoparticles were uniformly distributed within the highly graphitized mesoporous carbon matrix at the calcination temperature of 500 °C (represented by CeO₂/FeO_x@mC₅₀₀). However, the obtained nanoparticles were aggregated into large size when calcined at the temperatures of 700 and 900 °C. The CA 19-9 antibody can be anchored to the CeO₂/FeO_x@mC network through chemical absorption between carboxylic groups of antibody and CeO₂ or FeO_x by ester-like bridging. The CeO₂/FeO_x@mC₅₀₀-based immunosensor displayed superior sensing performance to the pristine CeFe-MOF, CeO₂/FeO_x@mC₇₀₀- and CeO₂/FeO_x@mC₉₀₀-based ones. Electrochemical impedance spectroscopy results showed that the developed immunosensor exhibited an extremely low detection limit of 10 μU·mL^-1 (S/N = 3) within a wide range from 0.1 mU·mL^-1 to 10 U·mL^-1 toward CA 19-9. It also illustrated excellent specificity, good reproducibility and stability, and acceptable application analysis in the human serum solution which was diluted 100-fold with 0.01 M PBS solution (pH 7.4) and spiked with different amounts of CA19-9. Consequently, the proposed electrochemical immunosensor is capable enough of determining CA 19-9 in clinical diagnostics.

Anchoring ultrafine PtNi nanoparticles on N-doped graphene for highly efficient hydrogen evolution reaction

One-step rapid synthesis of ultrafine PtNi nanoparticles anchored on –NH₂ and N doped graphene for highly efficient hydrogen evolution reaction.

Grafting and stabilization of ordered mesoporous silica COK-12 with graphene oxide for enhanced removal of methylene blue

Grafting of environmentally friendly produced ordered mesoporous silica (OMS) COK-12 with graphene oxide yields a superior OMS/GO adsorbent for methylene blue.

Construction of Cu-based MOFs with enhanced hydrogenation performance by integrating open electropositive metal sites

A kind of new Cu(ii)-MOF with open electropositive metal Cu sites exhibits excellent activity, selectivity and reusability in hydrogenation of 4-nitrophenol to 4-aminophenol under mild conditions (25 °C, 1 atm).