Facile Synthesis of Bimetallic Fluoride Heterojunctions on Defect-Enriched Porous Carbon Nanofibers for Efficient ORR Catalysts.

The development of efficient and stable catalysts for the oxygen reduction reaction (ORR) at low cost is crucial for realizing the large-scale application of metal-air batteries. Herein, we report an efficient ORR catalyst of bimetallic copper and cobalt fluoride heterojunctions, which are uniformly dispersed in nitrogen-fluorine-oxygen triply doped porous carbon nanofibers (PCNFs) that contain hierarchical macro-meso-micro pores. The composite catalyst materials are fabricated with a facile and green method of electrospinning with water as the solvent. By using poly(tetrafluoroethylene) as the pore inducer to anchor electropositive copper and cobalt salts in the electrospun hybrid nanofibers, bimetallic fluoride heterojunctions can be directly formed in PCNFs after calcination. The hierachical porous structures provide an effective way to transport matter, while the bimetallic fluorides expose abundant electroactive sites, both of which result in stable ORR activities with a high half-wave potential of 0.84 V. The study proposes a feasible strategy for the fabrication of nonprecious catalysts.

Accelerating Triple Transport in Zinc-Air Batteries and Water Electrolysis by Spatially Confining Co Nanoparticles in Breathable Honeycomb-Like Macroporous N-Doped Carbon.

Rational engineering electrode structure to achieve an efficient triple-phase contact line is vital for applications such as in zinc-air batteries and water electrolysis. Herein, a facile "MOF-in situ-leaching and confined-growth-MOF" strategy is developed to construct a breathable trifunctional electrocatalyst based on N-doped graphitic carbon with Co nanoparticles spatially confined in an inherited honeycomb-like macroporous structure (denoted as Co@HMNC). The unique orderly arranged macroporous channels and the "ships in a bottle" confinement effect jointly expedite the triple transport, endowing the catalysts with fast reaction kinetics. As a result, the obtained Co@HMNC catalyst presents superb trifunctional performance with a positive half-wave potential (E1/2 ) of 0.90 V for oxygen reduction reaction (ORR), and low overpotentials of 318 and 51 mV for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) at 10 mA cm-2 , respectively. The Co@HMNC-based liquid Zn-air battery reaches a large specific capacity of 859 mA h gZn -1 , a high-power density of 198 mW cm-2 , and long-term stability for 375 h, suggesting its promise for actual applications.

Nitrogen-Doped Amorphous Zn-Carbon Multichannel Fibers for Stable Lithium Metal Anodes.

The application of lithium metal anodes for practical batteries is still impeded by safety issues and low Coulombic efficiency caused mainly by the uncontrollable growth of lithium dendrites. Herein, two types of free-standing nitrogen-doped amorphous Zn-carbon multichannel fibers are synthesized as multifunctional hosts for lithium accommodation. The 3D macroporous structures endow effectively reduced local current density, and the lithiophilic nitrogen-doped carbon and functional Zn nanoparticles serve as preferred deposition sites with low nucleation barriers to guide uniform lithium deposition. As a result, the developed anodes exhibit remarkable electrochemical properties in terms of high Coulombic efficiency for more than 500 cycles at various current densities from 1 to 5 mA cm-2 , and symmetric cells show long-term cycling duration over 2000 h. Moreover, full cells based on the developed anode and a LiFePO4 cathode also demonstrate superior rate capability and stable cycle life.

Design and preparation of open circuit potential biosensor for in vitro and in vivo glucose monitoring.

A novel open circuit potential biosensor (OCPS) composed of a working electrode and a Ag/AgCl reference electrode was designed for in vivo continuous glucose monitoring in this work. The macroporous carbon derived from kenaf stem (KSC) was used to construct a KSC microelectrode (denoted as KSCME) which was subsequently used to load glucose oxidase (GOD) as the working electrode. The resulting GOD/KSCMEs could catalyze the oxidation of glucose directly to result in changes of the open circuit potential (V oc) of the OCPS. The V oc of OCPS was dependent on the glucose concentration, showing a linear range of 0.03-10.0 mM (R = 0.999) with a detection limit of 10 µM. In addition, the OCPS exhibited good selectivity for glucose over other common endogenous interferences. The feasibility of the proposed OCPS for glucose detection in mice skin tumors and normal tissue homogenate samples (in vitro experiment) and rat subcutaneous glucose monitoring (in vivo experiment) was also demonstrated with satisfactory results. The biosensor represents a novel example of a superficial cancer diagnostic device, and the proposed OCPS also provides new ideas for the development of a simple and highly selective device for continuous glucose sensing.

Au NPs modified Ni-B nanosheets/graphene oxide three-dimensional network as label-free electrochemical immunosensor for the detection of diethylstilbestrol.

Three-dimensional (3D) network provide a promising platform for construction of high sensitive electrochemical immunosensor due to the benefits of high specific surface area and electron mobility. Herein, a sensitive label-free electrochemical immunosensor based on Au nanoparticles modified Ni-B nanosheets/graphene matrix was constructed to detect diethylstilbestrol (DES). The 3D network not only could increase the electron transport rate and surface area, but also could provide confinement area, which is conducive to increases the collision frequency with the active site. Moreover, Au NPs also have good biocompatibility, which is beneficial for ligating antibodies. Benefiting from the 3D network structure and Au collective effect, the electrochemical immunosensor possess sterling detection ability with wide linear response range (0.00038-150 ng/mL) and low detection limit (31.62 fg/mL). Moreover, the constructed immunosensor can also be extend to detect DES in Tap-water and river water. This work may provide a novel material model for the construction of high sensitive immunosensor.

Dual-responsive electrochemical immunosensor for CYFRA21-1 detection based on Au/Co Co-loaded 3D ordered macroporous carbon interconnected framework.

Cytokeratin 19 fragment antigen 21-1 (CYFRA21-1) is a protein fragment released into the bloodstream during the death of lung epithelial cells, serving as a predictive biomarker in diagnosing non-small cell lung cancer (NSCLC) and need to be accurately detected. Herein, a dual-responsive label-free electrochemical immunosensor was developed based on a three-dimensional ordered interconnecting macroporous carbon skeleton material modified with gold-cobalt nanoparticles (Au/Co NPs-3D MCF) to detect cytokeratin-19 fragment (CYFRA21-1). The three-dimensional ordered interconnect macroporous structure, by providing a high specific surface area and an electrochemically active area, not only enhances the electron transport channel and reduces mass transfer resistance, but also offers a confined region that elevates the collision frequency with the active site. In addition to exhibiting excellent biocompatibility for antibody binding, gold-cobalt nanoparticles contribute significantly to the overall robustness of the immunosensor. By capitalizing on the 3D network structure and collective effect of Au and Co NPs, the Au/Co NPs-3D MCF immunosensors exhibit exceptional response signals in both chronocurrent testing and square-wave voltammetry, allowing for a wide linear response range of 0.0001-100 ng/mL and a low detection limit. Moreover, the constructed immunosensor is capable of detecting CYFRA21-1 in human serum and has the potential for further extension to detect multiple biomarkers. This work opens up new avenues for the construction of other highly selective 3D network immunosensors.

3D meso/macroporous carbon from MgO-templated pyrolysis of waste plastic as an efficient electrode for supercapacitors.

Converting waste plastic into valuable carbon materials as the electrode for supercapacitors represents a sustainable way to deal with the severe waste plastic-related environmental issues. However, ideal carbon materials for supercapacitors require not only a large specific surface area but also abundant meso/macropores, which is still challenging for conventional synthesis methods. Herein, MgO-templated pyrolysis with chemical activation was demonstrated as an effective approach to convert waste polyethylene terephthalate (PET) plastic bottles into 3D meso/macroporous carbon (MMPC) with both large total surface area (1863.55 m2/g) and meso/macropore surface area (1478.46 m2/g). Furthermore, it exhibited a high capacitance of 191.4 F/g and an excellent rate capability (86.3% retention from 0.5 to 10 A/g) for supercapacitor. This work provides not only a facile approach to synthesize 3D meso/macroporous carbon materials but also a sustainable way to mitigate plastic-derived pollution.

Electrocatalytically active cuprous oxide nanocubes anchored onto macroporous carbon composite for hydrazine detection.

Cuprous oxide (Cu2O) is a p-type semiconductor with excellent catalytic activity and stability that has gained much attention because it is non-toxic, abundant, and inexpensive. Porous carbon materials have large specific surface areas, which offer abundant electroactive sites, enhance the electrical conductivity of materials, and prevent the aggregation of Cu2O nanocubes. In this study, a composite with high electrocatalytic activity was prepared based on Cu2O nanocubes anchored onto three-dimensional macroporous carbon (MPC) by a simple, eco-friendly, and cheap method for hydrazine detection. Due to the synergistic effect of MPC and Cu2O, the sensor exhibited high electrocatalytic activity, sensitivity, better selectivity, and low limit of detection. The resulting sensor could be a sensitive and effective platform for detecting hydrazine and promising practical applications.

Simultaneous electrochemical determination of nitrophenol isomers based on macroporous carbon functionalized with amino-bridged covalent organic polycalix[4]arenes.

A glassy carbon electrode (GCE) modified by a hybrid, macroporous carbon (MPC) functionalized with triazine bridged covalent organic polycalix[4]arenes (CalCOP) (CalCOP-MPC), has been fabricated and utilized for simultaneous detection of nitrophenols (NP). The obtained CalCOP-MPC were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), which confirmed that MPC had functionalized with CalCOP successfully. Benefiting from the synergistic supramolecular effect of macrocyclic receptor of CalCOP and the excellent electrical properties of MPC, the anodic peaks of o-nitrophenol (o-NP), m-nitrophenol (m-NP), and p-nitrophenol (p-NP) in their mixture can be well separated by the prepared electrode. Differential pulse voltammetry (DPV) measurements at CalCOP-MPC/GCE revealed that the linear ranges of NP isomers were all 1-400 µM, and the detection limit limits were 0.383 µM, 0.122 µM, and 0.212 µM for o-NP, m-NP, and p-NP, respectively. Moreover, the prepared modified electrodes showed a relatively good selectivity and stability, implying the prospect for detecting NP in real environmental samples.

Facile one-pot synthesis of Co coordination polymer spheres doped macroporous carbon and its application for electrocatalytic oxidation of glucose.

Coordination polymers are highly desirable for various applications due to their functionality control of crystal structures. In this work, an unique class of amorphous Co coordination polymer spheres anchored onto 3D macroporous carbon (MPC) support (denoted as Co CPSs/MPC) was prepared via a facile hydrothermal method. The formation of Co CPSs/MPC was systematically verified by a series of characterizations, like scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction, etc. The synergic effects between the superior electrical conductivity of 3D MPC supports and the excellent electrocatalytic activity of Co CPSs result in the increase of electron transfer from electrocatalyst, and then form significant number available reactive sites on the surface of electrode, which exhibit an exceptional catalytic activity and oxidation ability towards glucose. Under optimized conditions, amperometry results also indicated that the Co CPSs/MPC exhibit excellent electroanalysis towards glucose. The current work can shed light on the promising Co CPSs/MPC for further exploited as a sensitive and simple non-enzymatic glucose analytical platform.

Single-Atom-like B-N3 Sites in Ordered Macroporous Carbon for Efficient Oxygen Reduction Reaction.

On the premise of cleanliness and stability, improving the catalytic efficiency for the oxygen reduction reaction in the electrode reaction of fuel cells and metal-air batteries is of vital importance. Studies have shown that heteroatom doping and structural optimization are efficient strategies. Herein, a single-atom-like B-N3 configuration in carbon is designed for efficient oxygen reduction reaction catalysis inspired by the extensively studied transition metal M-Nx sites, which is supported on the ordered macroporous carbon prepared by utilizing a hydrogen-bonded organic framework as carbon and nitrogen sources and SiO2 spheres as a template. The co-doping of B/N and ordered macroporous structures promote the metal-free material high oxygen reduction catalytic performance in alkaline media. DFT calculations reveal that the B-N3 structure played a key role in enhancing the oxygen reduction activity by providing rich favorable *OOH and *OH adsorption sites on the B center. The promoted formation of *OH/*OOH intermediates accelerated the electrocatalyst reaction. This study provides new insights into the design of single-atom-like nonmetallic ORR electrocatalysts and synthesis of ordered macroporous carbons based on hydrogen-bonded organic frameworks.

Direct Magnetic Reinforcement of Electrocatalytic ORR/OER with Electromagnetic Induction of Magnetic Catalysts.

Designing stable and efficient electrocatalysts for both oxygen reduction and evolution reactions (ORR/OER) at low-cost is challenging. Here, a carbon-based bifunctional catalyst of magnetic catalytic nanocages that can direct enhance the oxygen catalytic activity by simply applying a moderate (350 mT) magnetic field is reported. The catalysts, with high porosity of 90% and conductivity of 905 S m-1 , are created by in situ doping metallic cobalt nanodots (≈10 nm) into macroporous carbon nanofibers with a facile electrospinning method. An external magnetic field makes the cobalt magnetized into nanomagnets with high spin polarization, which promote the adsorption of oxygen-intermediates and electron transfer, significantly improving the catalytic efficiency. Impressively, the half wave-potential is increased by 20 mV for ORR, and the overpotential at 10 mA cm-2 is decreased by 15 mV for OER. Compared with the commercial Pt/C+IrO2 catalysts, the magnetic catalyzed Zn-air batteries deliver 2.5-fold of capacities and exhibit much longer durability over 155 h. The findings point out a very promising strategy of using electromagnetic induction to boost oxygen catalytic activity.

Facile preparation of CoMoO4 nanorods at macroporous carbon hybrid electrocatalyst for non-enzymatic glucose detection.

Glucose is a popular biosensor target due to its closely with diabetes or hypoglycemia in blood. Designing efficiency electrocatalysts for the determination of glucose is vital to develop glucose detection devices. CoMoO4, as a kind of bimetallic oxide material, exhibits unique electrochemical properties. 3D macroporous carbon (MPC) has large specific surface area and excellent electrical conductivity, providing an effective support for loading other nano-entities to form novel composite with good synergetic effects. Herein, nanorod-like CoMoO4 anchored onto MPC support was synthesized for the development of a promising electrochemical sensing platform for glucose. Attributing to the synergic effects between the good electrocatalytic performance of CoMoO4 nanorods and the extraordinary electrical conductivity of 3D layered MPC, the novel CoMoO4/MPC composites non-enzymatic sensor shows excellent electrocatalytic performance for oxidation of glucose. Under the optimum conditions, the proposed CoMoO4/MPC hybrids provided a reliable linear range of 5 × 10-7 to 1.08 × 10-4 M with a low limit of detection (0.13 µM) for the detection of glucose. Meanwhile, the CoMoO4/MPC sensing platform shows fast response time of 1.76 s, good stability and selectivity for detecting glucose. Moreover, this non-enzymatic sensor also has been successfully applied to measure glucose level in human blood samples. Therefore, the developed sensor holds a new promise for the construction of facile and sensitive non-enzymatic glucose analytical platform.

A Zeolitic-Imidazole Frameworks-Derived Interconnected Macroporous Carbon Matrix for Efficient Oxygen Electrocatalysis in Rechargeable Zinc-Air Batteries.

Nanostructures derived from zeolitic-imidazole frameworks (ZIFs) gain much interest in bifunctional oxygen electrocatalysis. However, they are not satisfied well for long-life rechargeable zinc-air batteries due to the limited single particle morphology. Herein, the preparation of an interconnected macroporous carbon matrix with a well-defined 3D architecture by the pyrolysis of silica templated ZIF-67 assemblies is reported. The matrix catalyst assembled zinc-air battery exhibits a high power density of 221.1 mW cm-2 as well as excellent stability during 500 discharging/charging cycles, surpassing that of a commercial Pt/C assembled battery. The synergistic effect from the interconnected macroporous structure together with abundant cobalt-nitrogen-carbon active sites justify the excellent electrocatalytic activity and battery performance. Considering the advanced nanostructures and performance, the as-synthesized hybrid would be promising for rechargeable zinc-air batteries and other energy technologies. This work may also provide significant concept in the view of electrocatalysis design for long-life battery.

Three-dimensional cubic ordered mesoporous carbon with chitosan for capacitive deionization disinfection of water.

Three-dimensional cubic ordered mesoporous carbon with chitosan (Ia3d-CS), which was synthesized via exothermic reaction between liquid potassium and carbon monoxide gas, was coated on the active carbon (AC) electrode as a capacitive deionization (CDI) disinfection electrode. The results showed that Ia3d-CS-2 as CDI electrode exhibited the quick ion diffusion and strong charge transfer performance, due to the three-dimensional pore structure and specific surface area. The electrode of Ia3d-CS-2 displayed a specific capacity of 191.22 F/g at a scan rate of 100 mV·s-1 in 0.5 M NaCl aqueous solution. In a CDI recycling system, Ia3d-CS-x electrode showed good cyclic stability, and the electrosorption capacity of Ia3d-CS-2 electrode can achieve 1.31 mg/g at 1.2 V in 100 mg/l NaCl aqueous solutions. Subsequently, Ia3d-CS-2 electrode had an excellent disinfection efficiency of killing about 99.99% Escherichia coli within 30 min during the CDI process at applied 1.2 V. Considering those excellent properties of the fabricated Ia3d-CS-x electrode, which should be a better candidate for high-performance deionization application.

Nano-casted N-Doped Carbon Created From a Task-Specific Protic Salt and Controlled Porous Glass.

3-dimensionally interconnected macroporous carbons are versatile materials that can be used in catalysis, electrochemical devices, and separation technology. Herein, the synthesis of a nitrogen doped carbonaceous material with a well-defined nanoarchitecture via nano-casting is demonstrated. A novel carbon source, a task-specific protic salt, has been proposed to create nitrogen doped carbon by direct carbonization within the pores of controlled macroporous glass. After the removal of macroporous glass from the composite using an aqueous sodium hydroxide solution and upon further heat treatment, an oxidation resistant doped carbon with high nitrogen content (6 mass %) is obtained. The materials formed during the different stages of the nano-casting process exhibit interesting properties such as hierarchical porosity, very high nitrogen content (15 mass %), and increased oxidational stability. A combination of different properties to create tailor-made materials for different applications using this technique is possible.

Hierarchically Macroporous Graphitic Nanowebs Exhibiting Ultra-fast and Stable Charge Storage Performance.

The macro/microstructures of carbon-based electrode materials for supercapacitor applications play a key role in their electrochemical performance. In this study, hierarchically macroporous graphitic nanowebs (HM-GNWs) were prepared from bacterial cellulose by high-temperature heating at 2400 °C. The HM-GNWs were composed of well-developed graphitic nanobuilding blocks with a high aspect ratio, which was entangled as a nanoweb structure. The morphological and microstructural characteristics of the HM-GNWs resulted in remarkable charge storage performance. In particular, the HM-GNWs exhibited very fast charge storage behaviors at scan rates ranging from 5 to 100 V s-1, in which area capacitances ranging from ~ 8.9 to 3.8 mF cm-2 were achieved. In addition, ~ 97% capacitance retention was observed after long-term cycling for more than 1,000,000 cycles.

Contrastive study on porphyrinic iron metal-organic framework supported on various carbon matrices as efficient electrocatalysts.

Porphyrinic iron metal-organic framework (pFeMOF) was combined with different kinds of carbon matrices, including porous graphene (PG), ordered mesoporous carbon (OMC) and macroporous carbon (MPC) via a simple one-step hydrothermal method. The introduction of carbon substrates improves the electrical conductivity and stability of pFeMOF. The presence of carbon also reduces the size of pFeMOF crystallites, leading to more active sites. The catalysts were used to electrocatalysis of hydrogen evolution reaction (HER) and the reduction of hydrogen peroxide (H2O2). Electrochemical measurements show that pFeMOF/PG has better electrocatalytic efficiency than pFeMOF/OMC, pFeMOF/MPC and pFeMOF. The HER on pFeMOF/PG displays a small onset potential of -34.37 mV vs. reversible hydrogen electrode (RHE), a low Tafel slope of 73.06 mV dec-1, a small over-potential of 154.71 mV at 10 mA cm-2. The catalytic effect for H2O2 is also satisfied. The linearity range of H2O2 is as wide as 5-4310 µM, and the sensitivity is as high as 77.38 µA mM-1. Such splendid performances may be attributed to the crumpled structure of PG leading to evenly and smaller pFeMOF. Furthermore, abundant hierarchical pores of pFeMOF/PG result in larger electrochemically surface areas. Our work may provide a new approach to design efficient non-precious metal catalysts.

Synthesis of nanosized 58S bioactive glass particles by a three-dimensional ordered macroporous carbon template.

Nanosized 58S bioactive glass (BG) particles were synthesized by using a three-dimensional ordered macroporous carbon template (OMC) with a pore size of 400nm. The obtained 58S BG particles possessed a diameter of 300nm, narrow size distribution and uniform spherical morphology. 58S/gelatin composites were prepared and showed much better mechanical properties than pure gelatin. The narrow size distribution of the 58S particles replicated from OMC was confirmed crucial to the mechanical properties of the 58S/gelatin composite, comparing to the contrast sample prepared with polydispersed particles. The outstanding bioactivity of the 58S BG particles was confirmed by inducing the formation of carbonated hydroxyapatite on the 58S/gelatin composite surface. This work showed a successful example that OMC template could be used to synthesize particles requiring a robust reaction condition, and a particle synthesis method that could well control particle size distribution was important for preparing materials with outstanding mechanical properties.

Macroporous Interconnected Hollow Carbon Nanofibers Inspired by Golden-Toad Eggs toward a Binder-Free, High-Rate, and Flexible Electrode.

Inspired by the favorable structure and shape of golden-toad eggs, a self-standing macroporous active carbon fiber electrode is designed and fabricated via a facile and scalable strategy. After being decorated with ruthenium oxide, it endows Li-O2 batteries with superior electrochemical performances.