Realizing Reversible Conversion‐Alloying of Sb(V) in Polyantimonic Acid for Fast and Durable Lithium‐ and Potassium‐Ion Storage

Finding suitable electrode materials for alkali‐metal‐ion storage is vital to the next‐generation energy‐storage technologies. Polyantimonic acid (PAA, H₂Sb₂O₆ · nH₂O), having pentavalent antimony species and an interconnected tunnel‐like pyrochlore crystal framework, is a promising high‐capacity energy‐storage material. Fabricating electrochemically reversible PAA electrode materials for alkali‐metal‐ion storage is a challenge and has never been reported due to the extremely poor intrinsic electronic conductivity of PAA associated with the highest oxidation state Sb(V). Combining nanostructure engineering with a conductive‐network construction strategy, here is reported a facile one‐pot synthesis protocol for crafting uniform internal‐void‐containing PAA nano‐octahedra in a composite with nitrogen‐doped reduced graphene oxide nanosheets (PAA?N‐RGO), and for the first time, realizing the reversible storage of both Li⁺ and K⁺ ions in PAA?N‐RGO. Such an architecture, as validated by theoretical calculations and ex/in situ experiments, not only fully takes advantage of the large‐sized tunnel transport pathways (0.37 nm²) of PAA for fast solid‐phase ionic diffusion but also leads to exponentially increased electrical conductivity (3.3 S cm^?1 in PAA?N‐RGO vs 4.8 × 10^?10 S cm^?1 in bare‐PAA) and yields an inside‐out buffer function for accommodating volume expansion. Compared to electrochemically irreversible bare‐PAA, PAA?N‐RGO manifests reversible conversion‐alloying of Sb(V) toward fast and durable Li⁺‐ and K⁺‐ion storage.     

Obstruction of Photoinduced Electron Transfer from Excited Porphyrin to Graphene Oxide: A Fluorescence Turn-On Sensing Platform for Iron (III) Ions

A comparative reaserch of the assembly of different porphyrin molecules on graphene oxide (GO) and reduced graphene oxide (RGO) was carried out, respectively. Despite the cationic porphyrin molecules can be assembled onto the surfaces of graphene sheets, including GO and RGO, to form complexes through electrostatic and π-π stacking interactions, the more obvious fluorescence quenching and the larger red-shift of the Soret band of porphyrin molecule in RGO-bound states were observed than those in GO-bound states, due to the differenc of molecular flattening in degree. Further, more interesting finding was that the complexes formed between cationic porphyrin and GO, rather than RGO sheets, can facilitate the incorporation of iron (III) ions into the porphyrin moieties, due to the presence of the oxygen-contained groups at the basal plane of GO sheets served as auxiliary coordination units, which can high-efficiently obstruct the electron transfer from excited porphyrin to GO sheets and result in the occurrence of fluorescence restoration. Thus, a fluorescence sensing platform has been developed for iron (III) ions detection in this contribution by using the porphyrin/GO nanohybrids as an optical probe, and our present one exhibited rapid and sensitive responses and high selectivity toward iron (III) ions.     

Y-shaped probe for convenient and label-free detection of microRNA-21 in vitro

A simple, highly selective, and label-free microRNA (miRNA) detection method based on l-alanine-reduced graphene oxide fluorescence quenching with a Y-shaped probe is proposed. The Y-shaped probe was synthesized by silver nitrate and a cytosine-rich molecular beacon (MB) in two terminals through sodium borohydride reduction, which generated a stronger fluorescent signal than ordinary DNA-templated silver nanoclusters (AgNCs). Meanwhile, the Y-shaped probe contained a single-stranded loop structure, which could be superbly adsorbed onto the surface of reduced graphene oxide (RGO) via π–π stacking interaction, and this special structure of the probe was designed to improve its sensitivity and selectivity. In addition, the quenching capacities of graphene oxide (GO) and RGO were compared in this research. The strong interaction between nucleobases of the loop structure and RGO nanosheet made the MB-AgNCs-RGO system exhibit minimal background fluorescence. In the presence of miRNA-21, the loop structure of the Y-shaped probe can hybridize with target miRNA-21; the molecular beacon encapsulated probe is far away from RGO surface and produces a detectable signal. The MB-AgNCs based approach provides a label-free avenue to detect miRNA with high selectivity and good reproducibility, which has a promising application in early clinical diagnosis and biomedical research.     

Formation of electrochemically reduced graphene oxide on melamine electrografted layers and its application toward the determination of methylxanthines

The current study describes the electrografting of 2,4-diamino-1,3,5-triazine (AT) groups at the surfaces of glassy carbon electrode (GCE) and indium tin oxide (ITO) through in situ diazotization of melamine. The presence of AT groups at the surface of the electrode was confirmed by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). Furthermore, graphene oxide (GO) was self-assembled on AT grafted GCE. The oxygen functional groups present on the surface of GO were electrochemically reduced to form an electrochemically reduced graphene oxide (ERGO) on AT grafted electrode surface. Raman spectra show the characteristic D and G bands at 1340 and 1605 cm⁻¹, respectively, which confirms the successful attachment of GO on AT grafted surface, and the ratio of D and G bands was increased after the electrochemical reduction of GO. EIS shows that the electron transfer reaction of [Fe(CN)₆]^3−/4− was higher at the ERGO modified electrode than at bare, AT grafted, and GO modified GCEs. The electrocatalytic activity of ERGO was investigated toward the oxidation of methylxanthines. It shows excellent electrocatalytic activity toward these methylxanthines by not only shifting their oxidation potentials toward less positive potentials but also enhancing their oxidation currents.     

Graphene‐Indanthrone Donor–π–Acceptor Heterojunctions for High‐Performance Flexible Supercapacitors

To overcome the low energy density bottleneck of graphene‐based supercapacitors and to organically endow them with high‐power density, ultralong‐life cycles, etc., one rational strategy that couple graphene sheets with multielectron, redox‐reversible, and structurally‐stable organic compounds. Herein, a graphene‐indanthrone (IDT) donor–π–acceptor heterojunction is conceptualized for efficient and smooth 6H⁺/6e^? transfers from pseudocapacitive IDT molecules to electrochemical double‐layer capacitive graphene scaffolds. To construct this, water‐processable graphene oxide (GO) is employed as a graphene precursor, and to in situ exfoliate IDT industrial dyestuff, followed by a hydrothermally‐induced reduction toward GO and self‐assembly between reduced GO (rGO) donors (D) and IDT acceptors (A), affording rGO‐π‐IDT D–A heterojunctions. Electrochemical tests indicate that rGO‐π‐IDT heterojunctions deliver a gravimetric capacitance of 535.5 F g^?1 and an amplified volumetric capacitance of 685.4 F cm^?3. The assembled flexible all‐solid‐state supercapacitor yields impressive volumetric energy densities of 31.3 and 25.1 W h L^?1, respectively, at low and high power densities of 767 and 38 554 W L^?1, while exhibiting an exceptional rate capability, cycling stability, and enduring mechanically‐challenging bending and distortions. The concept and methodology may open up opportunities for other two‐dimensional materials and other energy‐related devices.     

Improved stability and catalytic activity of graphene oxide/chitosan hybrid beads loaded with porcine liver esterase

Graphene oxide/chitosan and reduced graphene oxide/chitosan (GO/CS and RGO/CS) beads were prepared by precipitation with NaOH. Porcine liver esterase was immobilized on these beads to give GO/CS/E and RGO/CS/E beads. The optimum conditions for the maximum activity of RGO/CS/E beads were pH 8 and 50°C. The stability of the enzyme immobilized on GO/CS/E and RGO/CS/E was high in the pH range of 5–8. The GO/CS/E beads showed superior stability compared to that of the free enzyme and CS/E beads between 20 and 50°C. Kinetic analysis showed that GO/CS/E was a better catalyst than the RGO/CS/E beads with a lower K_m value of 0.9?mM. The hybrid beads also retained more than 95% activity after 10 consecutive cycles. The GO/CS/E and RGO/CS/E beads retained 84% and 87% activity after 40 days at 4°C. The GO/CS/E beads were used for the successful hydrolysis of methyl 4-hydroxy benzoate.     

A mechanically strong, flexible and conductive film based on bacterial cellulose/graphene nanocomposite

A highly flexible nanocomposite film of bacterial cellulose (BC) and graphene oxide (GO) with a layered structure was presented using the vacuum-assisted self-assembly technique. Microscopic and X-ray diffraction measurements demonstrated that the GO nanosheets were uniformly dispersed in the BC matrix. The interactions between BC and GO were studied by Fourier transformation infrared spectroscopy. Compared with pristine BC, the integration of 5 wt% GO resulted in 10% and 20% increase in Young's modulus and tensile strength of the composite film. The electrical conductivity of the composite film containing 1 wt% GO after in situ reduction showed a remarkable increase by 6 orders of magnitude compared with the insulated BC.     

Integration of Photosystem I with Graphene Oxide for Photocurrent Enhancement

Photosystem I is a photoactive membrane protein used in nature to photo‐excite electrons with nearly unit internal quantum efficiency, sparking interest in using this biomaterial for solar energy conversion. Films of PSI deposited on p‐doped silicon have previously demonstrated significant photocurrents with an electrochemical mediator; however, improvement in electron transfer is needed. Here, it is investigated how PSI can be combined with graphene oxide (GO) or reduced graphene oxide (RGO) to generate composite films capable of improved photoelectrochemical performance. It is found that both composite films outperformed the PSI film alone, and the PSI‐GO composite film is found to perform the best. The enhancement is attributed to the decreased impedance and shift in the onset potential of the composite films.     

A simple electrochemical approach to fabricate a glucose biosensor based on graphene-glucose oxidase biocomposite

We report a simple electrochemical approach for the immobilization of glucose oxidase (GOx) on reduced graphene oxide (RGO). The immobilization of GOx was achieved in a single step without any cross linking agents or modifiers. A simple solution phase approach was used to prepare exfoliated graphene oxide (GO), followed by electrochemical reduction to get RGO-GOx biocomposite. The direct electrochemistry of GOx was revealed at the RGO-GOx modified glassy carbon electrode (GCE). The electrocatalytic and electroanalytical applications of the proposed film were studied by cyclic voltammetry (CV) and amperometry. It is notable that the glucose determination has been achieved in mediator-free conditions. RGO-GOx film showed very good stability, reproducibility and high selectivity. The developed biosensor exhibits excellent catalytic activity towards glucose over a wide linear range of 0.1-27mM with a sensitivity of 1.85μAmM(-1)cm(-2). The facile and easy electrochemical approach used for the preparation of RGO-GOx may open up new horizons in the production of cost-effective biosensors and biofuel cells.     

Low‐Temperature Solution‐Based Phosphorization Reaction Route to Sn4P3/Reduced Graphene Oxide Nanohybrids as Anodes for Sodium Ion Batteries

Different from previously reported mechanical alloying route to synthesize Sn _x P₃, novel Sn₄P₃/reduced graphene oxide (RGO) hybrids are synthesized for the first time through an in situ low‐temperature solution‐based phosphorization reaction route from Sn/RGO. Sn₄P₃ nanoparticles combining with advantages of high conductivity of Sn and high capacity of P are homogenously loaded on the RGO nanosheets, interconnecting to form 3D mesoporous architecture nanostructures. The Sn₄P₃/RGO hybrid architecture materials exhibit significantly improved electrochemical performance of high reversible capacity, high‐rate capability, and excellent cycling performance as sodium ion batteries (SIBs) anode materials, showing an excellent reversible capacity of 656 mA h g^?1 at a current density of 100 mA g^?1 over 100 cycles, demonstrating a greatly enhanced rate capability of a reversible capacity of 391 mA h g^?1 even at a high current density of 2.0 A g^?1. Moreover, Sn₄P₃/RGO SIBs anodes exhibit a superior long cycling life, delivering a high capacity of 362 mA h g^?1 after 1500 cycles at a high current density of 1.0 A g^?1. The outstanding cycling performance and rate capability of these porous hierarchical Sn₄P₃/RGO hybrid anodes can be attributed to the advantage of porous structure, and the synergistic effect between Sn₄P₃ nanoparticles and RGO nanosheets.     

Sandwich‐Like Reduced Graphene Oxide/Carbon Black/Amorphous Cobalt Borate Nanocomposites as Bifunctional Cathode Electrocatalyst in Rechargeable Zinc‐Air Batteries

The inhibitively high cost of the noble‐metal‐containing materials has become a major obstacle for the large‐scale application of rechargeable zinc‐air batteries (ZABs). To solve this problem in a practical way, a green and scalable method to prepare sandwich‐like reduced graphene oxide /carbon black/amorphous cobalt borate nanocomposites (rGO/CB/Co‐B_i) is reported. These composites are shown to be a highly efficient and robust bifunctional electrocatalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this system, the spontaneous assembly of the GO sheet and CB nanoparticles is demonstrated by noncovalent interactions to build the sandwich‐like structure with hierarchical pore distribution. The impressive ORR and OER activities of the obtained nanocomposite are attributed to the high conductivity, large surface area, and the hierarchically porous channels. With room‐temperature synthesis and significant activities shown in the demonstrative battery test, the prepared nanocomposite can potentially serve as an alternative for noble‐metal‐based rechargeable ZAB cathode materials.     

High‐Energy Density Li‐Ion Capacitor with Layered SnS2/Reduced Graphene Oxide Anode and BCN Nanosheet Cathode

Lithium‐ion capacitors (LICs) with capacitor‐type cathodes and battery‐type anodes are considered a promising next‐generation advanced energy storages system that meet the requirements of high energy density and power density. However, the mismatch of charge‐storage capacity and electrode kinetics between positive and negative electrodes remains a challenge. Herein, layered SnS₂/reduced graphene oxide (RGO) nanocomposites are developed for negative electrodes and a 2D B/N codoped carbon (BCN) nanosheet is designed for the positive electrode. The SnS₂/RGO derived from SnS₂‐bonded RGO of high conductivity exhibits a capacity of 1198 mA h g^?1 at 100 mA g^?1. Boron and nitrogen atoms in BCN are found to promote adsorption of anions, which enhance the pseudocapacitive contribution as well as expanding the voltage of LICs. A quantitative kinetics analysis indicates that the SnS₂/RGO electrodes with a dominating capacitive mechanism and a diminished intercalation process, benefit the kinetic balance between the two electrodes. With this particular structure, the LIC is able to operate at the highest operating voltage for these devices recorded to date (4.5 V), exhibiting an energy density of 149.5 W h kg^?1, a power density of 35 kW kg^?1, and a capacity retention ratio of 90% after 10 000 cycles.     

Nitric oxide alleviates oxidative damage in the green alga<Emphasis Type="Italic">Chlorella pyrenoidosa</Emphasis> caused by UV-B radiation

The effect of ultraviolet-B radiation (UV-B; 280-320 nm) on induction of nitric oxide was estimated in the suspensions of green alga Chlorella pyrenoidosa with or without the NO scavenger N-acetyl-L-cysteine, and reductants such as 1,4-dithiothreitol, glutathione (reduced form), and ascorbic acid. Exogenously added sodium nitroprusside (NO donor), glutathione, 1,4-dithiothreitol, and ascorbic acid were able to prevent chlorophyll loss mediated by UV-B. Addition of NO to algal suspensions irradiated by UV-B increased the activity of catalase and superoxide dismutase but lowered the activity of phenylalanine ammonia-lyase. UV-B thus appears to be a strong inducer of NO production, exogenously added NO and reductants protecting the green alga against UV-B-induced oxidative damage.     

In Situ,Fast, High‐Temperature Synthesis of Nickel Nanoparticles in Reduced Graphene Oxide Matrix

For the first time, a fast heating–cooling process is reported for the synthesis of carbon‐coated nickel (Ni) nanoparticles on a reduced graphene oxide (RGO) matrix (nano‐Ni@C/RGO) as a high‐performance H₂O₂ fuel catalyst. The Joule heating temperature can reach up to ≈2400 K and the heating time can be less than 0.1 s. Ni microparticles with an average diameter of 2 µm can be directly converted into nanoparticles with an average diameter of 75 nm. The Ni nanoparticles embedded in RGO are evaluated for electro‐oxidation performance as a H₂O₂ fuel in a direct peroxide–peroxide fuel cell, which exhibits an electro‐oxidation current density of 602 mA cm^?2 at 0.2 V (vs Ag/AgCl), ≈150 times higher than the original Ni microparticles embedded in the RGO matrix (micro‐Ni/RGO). The high‐temperature, fast Joule heating process also leads to a 4–5 nm conformal carbon coating on the surface of the Ni nanoparticles, which anchors them to the RGO nanosheets and leads to an excellent catalytic stability. The newly developed nano‐Ni@C/RGO composites by Joule heating hold great promise for a range of emerging energy applications, including the advanced anode materials of fuel cells.     

Electrochemically Synthesized Polypyrrole/Graphene Composite Film for Lithium Batteries

A polypyrrole/reduced graphene oxide (PPy/r‐GO) composite film is prepared by inducing electrochemical reduction of graphene oxide incorporated into PPy as the dopant. This film has a wrinkled surface morphology with a porous structure as revealed by scanning electron microscopy. Its porous structure is attributed to the physical nature of the GO sheets, providing a templating effect during PPy deposition. This PPy/r‐GO composite is characterized using in‐situ UV–visible spectroelectrochemistry as well as Raman and Fourier‐transform IR spectroscopy. The PPy/r‐GO material shows greatly improved electrochemical properties, i.e., a high rate capability and excellent cycling stability when used as a cathode material in a lithium ion battery. It also delivers a large reversible capacity when used as an anode material, and this is mainly attributed to the reduced graphene oxide (r‐GO) component.     

Poly(vinylferrocene)–Reduced Graphene Oxide as a High Power/High Capacity Cathodic Battery Material

The preparation and performance of a new cathodic battery material consisting of a composite of poly(vinylferrocene) (PVFc) and reduced graphene oxide (rGO) is described. It shows the highest charge/discharge efficiency (at a rate of 100 A g^?1) ever reported for ferrocene–polymer materials. The composite allows for specific capacities up to 0.21 mAh cm^?2 (770 mC cm^?2, 29 μm film thickness) at a specific capacity density of 114 mAh g^?1 and less than 5% performance decay over 300 cycles. The composite material is binder free and the charge storing PVFc accounts for 88% of the total weight of the cathodic material. The superb performance is based on (i) perfect self‐assembling of oxidized PVFc on graphene oxide (GO) leading to PVFc@GO, (ii) its stepwise (n steps) transfer onto a current collector (CC) (PVFc@GO)_n@CC (n = drop casting steps), and (iii) the efficient electrochemical transformation of GO into rGO in the composite using viologen as homogeneous electrocatalyst. The self‐assembling step is analyzed by zeta potential and atomic force microscopy (AFM) studies, demonstrating heavy ferrocene loading on GO and a mesoporous composite structure, respectively. Complete GO/rGO transition and quantitative ClO₄ ^? ion breathing of the composite are found by electrochemical quartz crystal microbalance and by electrochemical AFM.     

石墨烯及其衍生物氧化石墨烯作为新型药物载体材料在肿瘤治疗领域的应用研究

石墨烯及其衍生物氧化石墨烯因具有水溶性好、比表面积大、载药量高以及易于修饰等优势,近年来在生物医药领域尤其在肿瘤治 疗领域的应用研究发展迅速。综述石墨烯及氧化石墨烯作为新型药物载体材料所具有的特性和生物安全性、表面修饰方式以及在肿瘤靶向 递药系统中的应用,为其在生物医药领域的应用研究提供新方法和新思路。     

Supercapacitor Electrodes Obtained by Directly Bonding 2D MoS2 on Reduced Graphene Oxide

Layered molybdenum disulfide (MoS₂) is deposited by microwave heating on a reduced graphene oxide (RGO). Three concentrations of MoS₂ are loaded on RGO, and the structure and morphology are characterized. The first layers of MoS₂ are detected as being directly bonded with the oxygen of the RGO by covalent chemical bonds (Mo‐O‐C). Electrochemical characterizations indicate that this electroactive material can be cycled reversibly between 0.25 and 0.8 V in 1 m HClO₄ solution for hybrids with low concentrations of MoS₂ layers (LCMoS₂/RGO) and between 0.25 and 0.65 V for medium (MCMoS₂/RGO) and high concentrations (HCMoS₂/RGO) of MoS₂ layers on graphene. The specific capacitance measured values at 10 mV s^?1 are 128, 265, and 148 Fg^?1 for the MoS₂/RGO with low, medium, and high concentrations of MoS₂, respectively, and the calculated energy density is 63 W h kg^?1 for the LCMoS₂/RGO hybrid. This supercapacitor electrode also exhibits superior cyclic stability with 92% of the specific capacitance retained after 1000 cycles.     

Removing of Disinfection By-Product Precursors from Surface Water by Using Magnetic Graphene Oxide

The magnetic graphene oxide (MGO) was successfully synthesised by the in situ chemical co-precipitation method with Fe³⁺, Fe²⁺ and graphene oxide (GO) in laboratory and, was used as an adsorbent for disinfection by-product (DBP) precursors removing from four natural surface water samples. The results indicate that various DBPs formation significantly decreased by 7–19% to 78–98% for the four samples after MGO treatment and, the treatment process was rapidly reached equilibrium within 20 minutes. The DBP precursors removal efficiency decreased with the increasing pH value from 4 to 10. Hydrophobic compounds (humic acid and fulvic acid) are more sensitive to MGO, whereas hydrophilic and nitrogenous compounds (aromatic proteins) are more insensitive. MGO could be regenerated by using 20% (v/v) ethanol and, the DBP precursors removal efficiency can stay stable after five cycles. These results indicate that MGO can be utilized as a promising adsorbent for the removal of DBP precursors from natural surface water.     

Molybdenum Disulfide/Nitrogen‐Doped Reduced Graphene Oxide Nanocomposite with Enlarged Interlayer Spacing for Electrocatalytic Hydrogen Evolution

Facile design of low‐cost and highly active catalysts from earth‐abundant elements is favorable for the industrial application of water splitting. Here, a simple strategy to synthesize an ultrathin molybdenum disulfide/nitrogen‐doped reduced graphene oxide (MoS₂/N‐RGO‐180) nanocomposite with the enlarged interlayer spacing of 9.5 Å by a one‐step hydrothermal method is reported. The synergistic effects between the layered MoS₂ nanosheets and N‐doped RGO films contribute to the high activity for hydrogen evolution reaction (HER). MoS₂/N‐RGO‐180 exhibits the excellent catalytic activity with a low onset potential of ?5 mV versus reversible hydrogen elelctrode (RHE), a small Tafel slope of 41.3 mV dec^?1, a high exchange current density of 7.4 × 10^?4 A cm^?2, and good stability over 5 000 cycles under acidic conditions. The HER performance of MoS₂/N‐RGO‐180 nanocomposite is superior to the most reported MoS₂‐based catalysts, especially its onset potential and exchange current density. In this work, a novel and simple method to the preparation of low‐cost MoS₂‐based electrocatalysts with the extraordinary HER performance is presented.