Electrochemically active porous carbon nanospheres prepared by inhibition of pyrolytic condensation of polymers.

Porous carbon is a pivotal material for electrochemical applications. The manufacture of porous carbon has relied on chemical treatments (etching or template) that require processing in all areas of the carbon/carbon precursor. We present a unique approach to preparing porous carbon nanospheres by inhibiting the pyrolytic condensation of polymers. Specifically, the porous carbon nanospheres are obtained by coating a thin film of ZnO on polystyrene spheres. The porosity of the porous carbon nanospheres is controlled by the thickness of the ZnO shell, achieving a BET-specific area of 1,124 m2/g with a specific volume of 1.09 cm3/g. We confirm that under the support force by the ZnO shell, a hierarchical pore structure in which small mesopores are connected by large mesopores is formed and that the pore-associated sp3 defects are enriched. These features allow full utilization of the surface area of the carbon pores. The electrochemical capacitive performance of porous carbon nanospheres was evaluated, achieving a high capacitance of 389 F/g at 1 A/g, capacitance retention of 71% at a 20-fold increase in current density, and stability up to 30,000 cycles. In particular, we achieve a specific area-normalized capacitance of 34.6 µF/cm2, which overcomes the limitations of conventional carbon materials.

Ultrasmall and Highly Dispersed Pt Entities Deposited on Mesoporous N-doped Carbon Nanospheres by Pulsed CVD for Improved HER.

Vapor-based deposition techniques are emerging approaches for the design of carbon-supported metal powder electrocatalysts with tailored catalyst entities, sizes, and dispersions. Herein, a pulsed CVD (Pt-pCVD) approach is employed to deposit different Pt entities on mesoporous N-doped carbon (MPNC) nanospheres to design high-performance hydrogen evolution reaction (HER) electrocatalysts. The influence of consecutive precursor pulse number (50-250) and deposition temperature (225-300 °C) are investigated. The Pt-pCVD process results in highly dispersed ultrasmall Pt clusters (≈1 nm in size) and Pt single atoms, while under certain conditions few larger Pt nanoparticles are formed. The best MPNC-Pt-pCVD electrocatalyst prepared in this work (250 pulses, 250 °C) reveals a Pt HER mass activity of 22.2 ± 1.2 A mg-1 Pt at -50 mV versus the reversible hydrogen electrode (RHE), thereby outperforming a commercially available Pt/C electrocatalyst by 40% as a result of the increased Pt utilization. Remarkably, after optimization of the Pt electrode loading, an ultrahigh Pt mass activity of 56 ± 2 A mg-1 Pt at -50 mV versus RHE is found, which is among the highest Pt mass activities of Pt single atom and cluster-based electrocatalysts reported so far.

NiCo2 O4 /Hollow Mesoporous Carbon Nanosphere Hybrids Enabling Super-Hydrophobicity, Thermal Insulation, and Highly Efficient Microwave Absorption.

The combination of 2D magnetic nanosheets and mesoporous carbon with unique interfaces shows considerable prospects for microwave absorption (MA). However, traditional assembly procedures make it impossible to accurately manage the assembly of magnetic nanosheets in carbon matrices. Herein, a reverse strategy for preparing complex magnetic nanosheet cores inside carbon-based yolk-shell structures is developed. This innovative approach focuses on controlling the initial crystallite formation sites in a hydrothermal reaction as well as the inflow and in situ growth behavior of 2D NiCo-layered double hydroxide precursors based on the capillary force induced by hollow mesoporous carbon nanospheres. Accordingly, the as-prepared YS-CNC-2 absorber exhibits remarkable MA performances, with an optimal reflection loss as low as -60.30 dB at 2.5 mm and an effective absorption bandwidth of 5.20 GHz at 2.0 mm. The loss of electromagnetic waves (EMW) depends on natural resonance loss, dipole polarization relaxation, and multiple scattering behavior. On top of that, the functionalized super-hydrophobic MA coating is produced in spraying and curing processes utilizing YS-CNC-2 nanoparticles and fumed silica additives in the polydimethylsiloxane matrix. The excellent thermal insulation, self-cleaning capability, and durability in diverse solutions of the coating promise potential applications for military equipment in moist situations.

Ultrahigh Mass Activity Pt Entities Consisting of Pt Single atoms, Clusters, and Nanoparticles for Improved Hydrogen Evolution Reaction.

Platinum is one of the best-performing catalysts for the hydrogen evolution reaction (HER). However, high cost and scarcity severely hinder the large-scale application of Pt electrocatalysts. Constructing highly dispersed ultrasmall Platinum entities is thereby a very effective strategy to increase Pt utilization and mass activities, and reduce costs. Herein, highly dispersed Pt entities composed of a mixture of Pt single atoms, clusters, and nanoparticles are synthesized on mesoporous N-doped carbon nanospheres. The presence of Pt single atoms, clusters, and nanoparticles is demonstrated by combining among others aberration-corrected annular dark-field scanning transmission electron microscopy, X-ray absorption spectroscopy, and electrochemical CO stripping. The best catalyst exhibits excellent geometric and Pt HER mass activity, respectively ≈4 and 26 times higher than that of a commercial Pt/C reference and a Pt catalyst supported on nonporous N-doped carbon nanofibers with similar Pt loadings. Noteworthily, after optimization of the geometrical Pt electrode loading, the best catalyst exhibits ultrahigh Pt and catalyst mass activities (56 ± 3 A mg-1 Pt and 11.7 ± 0.6 A mg-1 Cat at -50 mV vs. reversible hydrogen electrode), which are respectively ≈1.5 and 58 times higher than the highest Pt and catalyst mass activities for Pt single-atom and cluster-based catalysts reported so far.

Fe-Decorated Nitrogen-Doped Carbon Nanospheres as an Electrochemical Sensing Platform for the Detection of Acetaminophen.

In this work, Fe-decorated nitrogen-doped carbon nanospheres are prepared for electrochemical monitoring of acetaminophen. Via a direct pyrolysis of the melamine-formaldehyde resin spheres, the well-distributed Fe-NC spheres were obtained. The as-prepared Fe-NC possesses enhanced catalysis towards the redox of acetaminophen for abundant active sites and high-speed charge transfer. The effect of loading Fe species on the electrochemical sensing of acetaminophen is investigated in detail. The synergistic effect of nitrogen doping along with the above-mentioned properties is taken advantage of in the fabrication of electrochemical sensors for the acetaminophen determination. Based on the calibration plot, the limits of detection (LOD) were calculated to be 0.026 µM with a linear range from 0-100 µM. Additionally satisfactory repeatability, stability, and selectivity are obtained.

Temperature-Controlled Selectivity of Hydrogenation and Hydrodeoxygenation of Biomass by Superhydrophilic Nitrogen/Oxygen Co-Doped Porous Carbon Nanosphere Supported Pd Nanoparticles.

Selective hydrogenation and hydrodeoxygenation (HDO) of biomass to value-added products play a crucial role in the development of renewable energy resources. However, achieving a temperature-controlled selectivity within one catalytic system while retaining excellent hydrogenation and HDO performance remains a great challenge. Here, nitrogen/oxygen (N/O) co-doped porous carbon nanosphere derived from resin polymer spheres is synthesized as the host matrix to in situ encapsulate highly dispersed Pd nanoparticles (NPs). Through N/O co-doping, the defects on the surface of carbon structure can serve as active sites to promote substrate adsorption. After a facile H2 O2 post-treatment process, the presence of abundant carboxyl groups on the porous carbon nanospheres can act as acidic sites to replace the use of acidic additives in the HDO process. Additionally, the increased surface oxygen-containing groups improve hydrophilicity to disperse catalysts in aqueous solutions. Owing to the unique highly dispersed Pd NPs and abundant surface defects, the Pd@APF-H2 O2 (2.3 nm) catalysts exhibit excellent catalytic activity and temperature-controlled selectivity for hydrogenation and HDO products of biomass-derived vanillin.

Synergistic Effects in Ultrafine Molybdenum-Tungsten Bimetallic Carbide Hollow Carbon Architecture Boost Hydrogen Evolution Catalysis and Lithium-Ion Storage.

Constructing hierarchical heterostructures is considered a useful strategy to regulate surface electronic structure and improve the electrochemical kinetics. Herein, the authors develop a hollow architecture composed of MoC1- x and WC1- x carbide nanoparticles and carbon matrix for boosting electrocatalytic hydrogen evolution and lithium ions storage. The hybridization of ultrafine nanoparticles confined in the N-doped carbon nanosheets provides an appropriate hydrogen adsorption free energy and abundant boundary interfaces for lithium intercalation, leading to the synergistically enhanced composite conductivity. As a proof of concept, the as-prepared catalyst exhibits outstanding and durable electrocatalytic performance with a low overpotential of 103 and 163 mV at 10 mA cm-2 , as well as a Tafel slope of 58 and 90 mV dec-1 in alkaline electrolyte and acid electrolyte, respectively. Moreover, evaluated as an anode for a lithium-ion battery, the as-resulted sample delivers a rate capability of 1032.1 mA h g-1 at 0.1 A g-1 . This electrode indicates superior cyclability with a capability of 679.1 mA h g-1 at 5 A g-1 after 4000 cycles. The present work provides a strategy to design effective and stable bimetallic carbide composites as superior electrocatalysts and electrode materials.

Constructing Atomic Fe and N Co-doped Hollow Carbon Nanospheres with a Polymer Encapsulation Strategy for High-Performance Lithium-Sulfur Batteries with Accelerated Polysulfide Conversion.

As competitive next-generation rechargeable batteries, lithium-sulfur batteries (LSBs) suffer from the shuttle effect and the sluggish kinetics of intermediate polysulfides during charge and discharge processes, adversely affecting their electrochemical performances and actual applications. Herein, we demonstrate a polymer encapsulation strategy to synthesize atomic Fe and N co-doped hollow carbon nanospheres (Fe-NHC) with Fe-Nx sites for modifying commercial PP separator of LSBs to suppress the shuttle effect and promote the kinetics of intermediate polysulfides. Benefiting from the excellent structural design, the doped-N with positive charges could effectively adsorb negatively charged soluble polysulfides, help attract the soluble polysulfides to the Fe atoms and boost the catalytic transformation of the soluble polysulfides. Additionally, such a thin carbon shell could provide a short mass diffusion pathway and hence promote the adsorption and the catalytic conversion. Therefore, the battery with the Fe-NHC/PP separator delivers outstanding cycling and rate performances. At the large current density of 1 C, the specific capacity is 1079 mA h g-1 and maintains a low loss of 0.076 % per cycle within 500 cycles. Even at a harsh current density of 4 C, a high capacity of 824 mA h g-1 is still achieved, indicating the advantage of the Fe-NHC/PP separator in LSBs.

Boron and nitrogen co-doped carbon nanospheres for supercapacitor electrode with excellent specific capacitance.

At present, carbon materials derived from biomass precursors have many limitations in the field of energy storage. In this study, boron and nitrogen (B/N) co-doped carbon nanospheres are successfully prepared by emulsion crosslinking method using chitosan and boric acid as raw materials. After carbonization at high temperature, the carbon nanospheres can be facilely prepared with controllable particle size, showing excellent structural stability and sphericity. In addition, the heteroatoms co-doping endows the carbon nanospheres with large specific surface area, high graphitization degree and excellent electrochemical performance. Applying the carbon nanospheres for supercapacitors, the specific capacitance can reach up to 336.7 F g-1at a current density of 1 A g-1. Even after 10,000 cycles, the Coulomb efficiency and specific capacitance still remain at 98.61% and 96.8%, respectively, demonstrating the great promise of B/N co-doped carbon nanospheres for the state-of-the-art supercapacitor electrodes applications.

Sea urchin-like CoNi2S4materials derived from nickel hexamyanocobaltate for high-performance asymmetric hybrid supercapacitor.

In this work, a mild chemical precipitation method and simple hydrothermal treatment of the nickel hexamyanocobaltate precursor strategy are developed to prepare a sea urchin-like CoNi2S4compound with remarkable specific capacity and excellent cycling stability. The prepared CoNi2S4has an outstanding specific capacity of 149.1 mA h g-1at 1 A g-1and an initial capacity of 83.1% after 3000 cycles at 10 A g-1. Moreover, the porous carbon nanospheres (PCNs) with exhibit cycling stability (94.7% of initial specific capacity after 10 000 cycles at 10 A g-1) are selected as negative electrode to match CoNi2S4positive electrode for assembly of CoNi2S4//PCNs asymmetric supercapacitor (ASC). Satisfactorily, the as-assembled CoNi2S4//PCNs ASC exhibits an impressive energy density of 41.6 Wh kg-1at 797 W kg-1, as well as the suitable capacity retention of 82.8% after 10 000 cycles. The superior properties of the device demonstrated that the as-prepared material is potential energy storage material.

MIL-53(Fe)-derived ant nest structured porous carbon nanospheres CuFeS2 /C for the determination of atropine enantiomeric impurity L-hyoscyamine.

In this work, an ant nest structured porous carbon nanosphere had been developed for the recognition detection of the atropine (ATP) enantiomers D-hyoscyamine (D-HSM) and L-hyoscyamine (L-HSM). Firstly, Fe-based organic framework was used as the substrate, and Cu ions and sulfur ions were separately introduced to obtain CuFeS2 with ant nest structure by hydrothermal incubation. Then CuFeS2 /C porous nanospheres (PNSs) were obtained by high-temperature calcination. The composite-modified electrode exhibited superior electrochemical performance for L-HSM due to the synergistic effect of CuFeS2 cubic crystals and porous carbon, which has the high specific surface area of the ant nest structure. In addition, the molecularly imprinted polymer (MIP) about L-HSM formed with sulfonated-ß-cyclodextrin (S-ß-CD) and L-arginine (L-Arg) by cyclic voltammetry showed strong chiral recognition of D/L-HSM (ATP). Therefore, a novel electrochemical sensor was constructed based on CuFeS2 /C PNSs and MIP to detect L-HSM by differential pulse voltammetry. Under the optimal conditions, the peak current density of L-HSM showed a good linearity in the concentration range of 0.02-4.6 µM with LOD and LOQ of 0.45 and 1.5 nM, respectively. The oxidation peaks of L-HSM and D-HSM were successfully identified from the racemic ATP, and the oxidation peak potential difference (ΔEp ) between them was 0.138 V. In conclusion, the sensor showed excellent reproducibility, repeatability, and stability and had been applied to the determination of L-HSM in human serum, saliva, and ATP sulfate tablets with satisfactory results.

Biowaste-Derived, Highly Efficient, Reusable Carbon Nanospheres for Speedy Removal of Organic Dyes from Aqueous Solutions.

The current work explores the adsorptive efficiency of carbon nanospheres (CNSs) derived from oil palm leaves (OPL) that are a source of biowaste. CNSs were synthesized at 400, 600, 800 and 1000 °C, and those obtained at 1000 °C demonstrated maximum removal efficiency of ~91% for malachite green (MG). Physicochemical and microscopic characteristics were analysed by FESEM, TEM, FTIR, Raman, TGA and XPS studies. The presence of surface oxygen sites and the porosity of CNSs synergistically influenced the speed of removal of MG, brilliant green (BG) and Congo red (CR) dyes. With a minimal adsorbent dosage (1 mg) and minimum contact time (10 min), and under different pH conditions, adsorption was efficient and cost-effective (nearly 99, 91 and 88% for BG, MG and CR, respectively). The maximum adsorption capacities of OPL-based CNSs for BG were 500 and 104.16 mg/g for MG and 25.77 mg/g for CR. Adsorption isotherms (Freundlich, Langmuir and Temkin) and kinetics models (pseudo-first-order, pseudo-second-order and Elovich) for the adsorption processes of all three dyes on the CNSs were explored in detail. BG and CR adsorption the Freundlich isotherm best, while MG showed a best fit to the Temkin model. Adsorption kinetics of all three dyes followed a pseudo-second-order model. A reusability study was conducted to evaluate the effectiveness of CNSs in removing the MG dye and showed ~92% efficiency even after several cycles. Highly efficient CNSs with surface oxygen groups and speedy removal of organic dyes within 10 min by CNSs are highlighted in this paper.

A Photoresponsive Nanozyme for Synergistic Catalytic Therapy and Dual Phototherapy.

Dual phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), has shown a great prospect in cancer treatment. However, its therapeutic effect is restricted by the depth of light penetration in tissue and tumor hypoxia environment. Herein, inspired by the specific response of nanozymes to the tumor microenvironment (TME), a simple and versatile nanozyme-mediated synergistic dual phototherapy nanoplatform (denoted as FePc/HNCSs) is constructed using hollow nitrogen-doped carbon nanospheres (HNCSs) and iron phthalocyanine (FePc). FePc/HNCSs simultaneously exhibit peroxidase (POD)- and catalase (CAT)-like activities, which not only can convert endogenous hydrogen peroxide (H2 O2 ) into highly toxic hydroxyl radicals (•OH) for catalytic therapy, but also decompose H2 O2 to oxygen (O2 ) to enhance O2 -dependent PDT. In addition, their enzyme-like activities are significantly enhanced under light irradiation. Combining with the excellent photothermal effect, FePc/HNCSs realize a high tumor inhibition rate of 96.3%. This strategy opens a new horizon for exploring a more powerful tumor treatment nanoplatform.

Hollow Carbon Sphere-Modified Graphitic Carbon Nitride for Efficient Photocatalytic H2 Production.

A novel hybrid photocatalyst composed of hollow carbon nanospheres (NCS) and graphitic carbon nitride (CN) curly nanosheets has been prepared by the calcination of a NCS precursor and freeze-dried urea. The optimized photocatalyst exhibits an efficient photocatalytic performance under visible light irradiation with a highest H2 generation rate of 3612.3 µmol g-1 h-1 , leading to an apparent quantum yield of 10.04 % at 420 nm, five times higher than the widely reported benchmark photocatalyst CN (2.01 % AQY). The materials characterization shows that NCS-modified CN curly nanosheets can promote photoelectron transfer and suppress charge recombination through their special coupling interface and NCS as an electron acceptor, which significantly improves the photocatalytic efficiency. Thus, this study provides an efficient strategy for the design of highly efficient photocatalyst, particularly suitable for a totally metal-free photocatalytic system.

NiCo2S4nanosheets decorated on nitrogen-doped hollow carbon nanospheres as advanced electrodes for high-performance asymmetric supercapacitors.

Taking advantage of both Faradaic and carbonaceous materials is an efficient way to synthesize composite electrodes with enhanced performance for supercapacitors. In this study, NiCo2S4nanoflakes were grown on the surface of nitrogen-doped hollow carbon nanospheres (NHCSs), forming a NiCo2S4/NHCS composite with a core-shell structure. This three-dimensionally confined growth of NiCo2S4can effectively inhibit its aggregation and facilitate mass transport and charge transfer. Accordingly, the NiCo2S4/NHCS composite exhibited high cycling stability with only 9.2% capacitance fading after 10 000 cycles, outstanding specific capacitance of 902 F g-1at 1 A g-1, and it retained 90.6% of the capacitance at 20 A g-1. Moreover, an asymmetric supercapacitor composed of NiCo2S4/NHCS and activated carbon electrodes delivered remarkable energy density (31.25 Wh kg-1at 750 W kg-1), excellent power density (15003 W kg-1at 21.88 Wh kg-1), and satisfactory cycling stability (13.4% capacitance fading after 5000 cycles). The outstanding overall performance is attributed to the synergistic effect of the NiCo2S4shell and NHSC core, which endows the composite with a stable structure, high electrical conductivity, abundant active reaction sites, and short ion-transport pathways. The synthesized NiCo2S4/NHCS composite is a competitive candidate for the electrodes of high-performance supercapacitors.

Metallo-deuteroporphyrins derived multi-layered hollow carbon spheres electrocatalysts for highly efficient oxygen reduction reaction.

The development of low-cost, highly efficient and stable non-precious metal electrocatalyst for the oxygen reduction reaction (ORR) substituting Pt has attracted much attention. Herein, we developed a promising structural platform for the fabrication of carbon nanospheres functionalized with hollow nanostructures of M-NHCS (M = Fe, Co and Mn) based on metallo-deuteroporphyrins (MDP). Benefited from the multi-layered active sites and hollow substrate with more exposed active surface area, convenient channels for the transport of electrons, the resulting Fe-NHCS electrocatalysts exhibit enhanced electrocatalytic performance in ORR with an onset potential of 0.90 V (versus RHE), and a high selectivity in the direct 4-electron pathway. The Fe-NHCS electrocatalysts also show a good methanol tolerance superior to Pt/C catalysts and an extremely high stability with only 13.0 mV negative after 5000 cycles in alkaline media. Experiments have verified that maintaining the multi-layered Fe-N-C active sites and hollow substrate were essential to deliver the high performance for ORR. The work opens new avenues for utilizing MDP-based materials in future energy conversion applications.

Hollow nitrogen-doped carbon nanospheres as cathode catalysts to enhance oxygen reduction reaction in microbial fuel cells treating wastewater.

Hollow nanospheres play a pivotal role in the electro-catalytic oxygen reduction reaction (ORR), which is a crucial step in microbial fuel cell (MFC) device. Herein, the hollow nitrogen-doped carbon nanospheres (HNCNS) were synthesized with the sacrifice of silica coated carbon nanospheres (CNS@SiO2) as template. HNCNS remarkably enhanced the ORR activity compared to the solid carbon and solid silica spheres. By tuning calcination temperature (800-1100 °C), the surface chemistry properties of HNCNS were effectively regulated. The optimal HNCNS-1000 catalyst which was calcined at 1000 °C exhibited the highest ORR activity in neutral media with the onset potential of 0.255 V and half-wave potential of -0.006 V (vs. Ag/AgCl). Single chamber MFC (SCMFC) assembled with HNCNS-1000 cathode unveiled comparable activity to a conventional Pt/C reference. It showed the highest maximum power density of 1307 ± 26 mW/m2, excellent output stability of 5.8% decline within 680 h, chemical oxygen demand (COD) removal of 94.0 ± 0.3% and coulombic efficiency (CE) of 7.9 ± 0.9%. These excellent results were attributed to a cooperative effect of the optimized surface properties (e.g., structural defects, relative content of pyrrolic nitrogen and specific surface area) and the formation of hollow nanosphere structure. Furthermore, the positive linear relationship of the structural defects and pyrrolic nitrogen species with the maximum power generation in SCMFC were clearly elucidated. This study demonstrated that the cost effective HNCNS-1000 was a promising alternative to commercial Pt/C catalyst for practical application in MFCs treating wastewater. Our result revealed the effectiveness of MFC fabricated with HNCNS-1000 cathode catalyst in terms of power generation and wastewater treatment.

NIR-II-activated biocompatible hollow nanocarbons for cancer photothermal therapy.

Photothermal therapy has attracted extensive attentions in cancer treatment due to its precise spatial-temporal controllability, minimal invasiveness, and negligible side effects. However, two major deficiencies, unsatisfactory heat conversion efficiency and limited tissue penetration depth, hugely impeded its clinical application. In this work, hollow carbon nanosphere modified with polyethylene glycol-graft-polyethylenimine (HPP) was elaborately synthesized. The synthesized HPP owns outstanding physical properties as a photothermal agent, such as uniform core-shell structure, good biocompatibility and excellent heat conversion efficiency. Upon NIR-II laser irradiation, the intracellular HPP shows excellent photothermal activity towards cancer cell killing. In addition, depending on the large internal cavity of HPP, the extended biomedical application as drug carrier was also demonstrated. In general, the synthesized HPP holds a great potential in NIR-II laser-activated cancer photothermal therapy.

Cu2+-modified hollow carbon nanospheres: an unusual nanozyme with enhanced peroxidase-like activity.

A Cu2+-modified carboxylated hollow carbon nanospheres (Cu2+-HCNSs-COOH) was designed with enhanced peroxidase-like activity for the detection of hydrogen peroxide (H2O2) and degradation of methylene blue (MB). Hollow polymer nanospheres were fabricated from aniline, pyrrole, Triton-100, and ammonium persulfate via confined interfacial copolymerization reaction, which can be pyrolyzed to create HCNSs with the hollow gap diameter of about 20 nm under high temperature. Combining the synergistic effect of coordination and electrostatic interaction, Cu2+-HCNSs-COOH was constructed by anchoring Cu2+ on the surface of HCNSs-COOH. Furthermore, Cu2+-HCNSs-COOH has higher affinity for 3,3',5,5'-tetramethylbenzidine and H2O2 of 0.20 mM and 0.88 mM, respectively. Based on the rapid response of Cu2+-HCNSs-COOH to H2O2, we constructed a colorimetric sensing platform by detecting the absorbance of the 3,3',5,5'-tetramethylbenzidine-H2O2 system at 652 nm for quantifying H2O2, which holds good linear relationship between 1 and 150 µM and has a detection limit of 0.61 µM. We also investigated the degradation of MB in the presence of Cu2+-HCNSs-COOH and H2O2, which can degrade 80.7% pollutants within 30 min. This research developed an unusual nanozyme for bioassays and water pollution treatment, which broadened the way for the rapid development of clinical diagnostics and water pollution treatment.

Highly Curved Nanostructure-Coated Co, N-Doped Carbon Materials for Oxygen Electrocatalysis.

Nitrogen-doped graphene could catalyze the electrochemical reduction and evolution of oxygen, but unfortunately suffers from sluggish catalytic kinetics. Herein, for the first time, we report an onion-like carbon coated Co, N-doped carbon (OLC/Co-N-C) material, which possesses multilayers of highly curved nanostructures that form mesoporous architectures. These unique nanospheres are produced when surfactant micelles are introduced to synthesis precursors. Owing to the combined electronic effect and nanostructuring effect, our OLC/Co-N-C materials exhibit high bifunctional oxygen reduction/evolution reaction (ORR/OER) activity, showing a promising application in rechargeable Zn-air batteries. Experimental results are rationalized by theoretical calculations, showing that the curvature of graphitic carbon plays a vital role in promoting activities of meta-carbon atoms near graphitic N and ortho/meta carbon atoms close to pyridinic N.