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Three-dimensional core–shell-structured TiO2@PPy/rGO nanocomposites were successfully constructed from TiO2@PPy nanospheres and graphene oxide via a polymerization method. First, TiO2 nanoparticles were uniformly coated with polypyrrole (PPy), forming core–shell TiO2@PPy nanospheres. The as-prepared TiO2@PPy nanospheres further self-assembled with graphene oxide (GO), resulting in the formation of three-dimensional ternary TiO2@PPy/rGO nanocomposites. Due to the strong interactions between TiO2@PPy and reduced graphene oxide (rGO), the three-dimensional TiO2@PPy/rGO electrode exhibited larger specific capacitance, lower charge transfer resistance, and more stable cycling performance compared to the TiO2@PPy nanospheres. More importantly, the existence of rGO increased the cycling stability of PPy and improved the capacitive performance, thus further demonstrating the positive effects of rGO, achieving a highest specific capacitance of 462.1 F g−1 at a current density of 0.5 A g−1. The present strategy will pave the way for the development of a new generation of advanced electrode materials for energy storage. [ABSTRACT FROM AUTHOR]

N-doped graphene oxide (NGO) thin film is synthesized by irradiation of graphene oxide (GO) thin film in NH 3 atmosphere. NGO thin film obtained by irradiation of GO thin film for 60 min has a high N-doping level of 12.69 at.%, and the amino-like N dominates the doping with the level of 7.90 at.%. The photoconductivity properties of NGO thin film under white-light illumination have been systematically examined. The results show that compared to reduced graphene oxide (rGO) thin film, NGO thin film exhibits significant photoconductivity enhancement with a high ratio of 2000%, and shows a faster photoresponse. The current responsivity and external quantum efficiency values for the NGO film reach ∼31 mA W −1 and ∼87% at 2 V, respectively. It may attribute to the high doping level of amino-like N on the basal plane and the pyridine-like N at the vacancy-site of graphene sheets, which can offer substantial photocarriers and the effective transfer to the electrodes. [ABSTRACT FROM AUTHOR]

By using simple irradiation of graphene oxide (GO) thin films in NH atmosphere, nitrogen-doped GO (NGO) thin films had been successfully synthesized. It is notable that the reduction and nitrogen doping of graphene are simultaneously achieved by irradiation, and the nitrogen content of NGO could reach as high as 12.34 at.% within only 5 min. With further prolonging the irradiation time to 120 min, it could reach a very high value of 17.21 at.%. The electrical properties of NGO thin films were investigated. The results showed that, compared to irradiation of GO films in Ar atmosphere, irradiation in NH atmosphere is much more effective to improve the electrical conductivity. It may attribute to the nitrogen doping and oxygen reduction, both of which can effectively enhance the electrical conductivity. [ABSTRACT FROM AUTHOR]

Nitrogen-doped graphene oxide (NGO) was synthesized by irradiation of graphene oxide (GO) in NH3 atmosphere. NGO obtained by irradiation of GO for 10 min has high N content of 13.62 at. %. The photoluminescence (PL) properties of NGO were investigated. The results showed that compared with GO, NGO exhibits significant PL enhancement with a high enhancement ratio of approximately 1501.57%. It may attribute to the high content of amino-like N, which can effectively enhance PL of GO because of the amino conjugation effect. [ABSTRACT FROM AUTHOR]

[Display omitted] • A H 2 -realeasing MN patch realeases hydrogen at the deep site of diabetic wound continually. • Self-responsive H 2 -releasing microneedle patch accelerates diabetic wound healing by sequential action of H 2 and Co2+. • Sequential release of H 2 and Co2+ is achieved through the interaction of the microneedle and the backing. • An MN patch achieving integration and spatiotemporal control of antibacterial, ROS regulation, and proangiogenic functions. Oxidative stress regulation and synchronized promotion of angiogenesis are critical factors in the healing process of diabetic wounds. However, existing research often fails to fully consider the dynamic interplay between these two biological processes and their time-dependent roles in diabetic wound healing. This study innovatively introduces a novel hydrogen (H 2)-releasing microneedle patch capable of precisely controlling the regulation of oxidative stress and the promotion of angiogenesis through a bidirectional responsive mechanism of microneedles and backing layers. Specifically, we employ ammonia borane (AB)-loaded mesoporous silica nanoparticles (MSN) as a source of H 2 , combined with polyvinyl pyrrolidone (PVP) to fabricate microneedles. This design effectively clears excessive reactive oxygen species (ROS) in deep tissues and promotes the M2 polarization of macrophages. Concurrently, we utilize cobalt-adsorbed graphene oxide (GO/Co2+) mixed with polyvinyl alcohol (PVA) to prepare backing layers, which not only release Co2+ upon the reduction of oxygen-containing functional groups in GO by H 2 diffused from deep tissues to synergize with H 2 for enhanced vascularization, but also endow the microneedle patch with near-infrared (NIR) light-responsive antimicrobial properties, crucial for managing diabetic infected wounds. Through this innovative dual-action mechanism, our research significantly accelerates the healing process of infected wounds in a diabetic mouse model. Moreover, single-cell sequencing results further confirm the pivotal role of H 2 in regulating oxidative stress, promoting macrophage M2 polarization, and stimulating angiogenesis. These results not only showcase the unique features of our microneedle patch but also offer new perspectives and therapeutic strategies for the treatment of diabetic wounds. [ABSTRACT FROM AUTHOR]

Inducing magnetic moments in graphene is very important for its potential application in spintronics. Introducing sp3-defects on the graphene basal plane is deemed as the most promising approach to produce magnetic graphene. However, its universal validity has not been very well verified experimentally. By functionalization of approximately pure amino groups on graphene basal plane, a spin-generalization efficiency of ~1 μB/100 NH2 was obtained for the first time, thus providing substantial evidence for the validity of inducing magnetic moments by sp3-defects. As well, amino groups provide another potential sp3-type candidate to prepare magnetic graphene. [ABSTRACT FROM AUTHOR]

The homogeneous distribution of nano-sulfur onto 3D structures for the development of high-performance Li-S batteries (LSBs) is a top concern to solve the low utilization of sulfur, sluggish redox kinetics, and lithium polysulfide (LiPS) shuttle effect. Herein, a novel "egg tray" hierarchical architecture of confining and uniformly distributing nano-sulfur into a 3D holey graphene (HG) framework with polyaniline crosslinking (3DHG/NS/CPANI) via photo-assisted method was designed for high-mass-loading LSB cathode. Notably, HG contains both conductive skeletons as electron transfer paths and abundant void spaces in favor of homogenous sulfur anchoring. This configuration improves the contact between nano-sulfur and graphene for effective charge transportation and provides buffering space for volume variations during electrochemical processes. Moreover, a facile photo-assisted method was developed to cross link HG with polyaniline to act as an efficient polysulfide adsorbent, allowing nano-sulfur (NS) to be firmly embedded into the holes of graphene through physical and chemical effects, thus prohibiting the dissolution and shuttle effect of polysulfide. Considering these advantages, the prepared 3DHG/NS/CPANI electrode exhibited excellent performance with high sulfur utilization and specific capacity, resulting in specific discharge capacities at 0.5 and 1C of 1082 and 921 mA h −1, respectively, and small capacity decay of 0.04% per cycle over 500 cycles at 1C. The strategy in this work, which synergistically combines morphology control, nano-sulfur positioning, and structural engineering to enhance the electrochemical performance for Li−S batteries, will offer a valuable reference to energy storage and conversion advances. A novel "egg tray" hierarchical architecture of confining and uniformly distributing nano-sulfur into a 3D holey graphene (HG) framework with polyaniline crosslinking (3DHG/NS/CPANI) via photo-assisted method was designed. HG contains both conductive skeletons as electron transfer paths and abundant void spaces in favor of homogenous sulfur anchoring. This configuration improves the contact between nano-sulfur and graphene for effective charge transportation and provides buffering space for volume variations during electrochemical processes. Moreover, interchain cross-linking of polyaniline and covalent bonding of polyaniline to graphene oxide were realized by a photo-assisted cross-linking strategy to improve the chemical immobilization for polysulfides. Considering these advantages, the prepared 3DHG/NS/CPANI electrode exhibited excellent performance with high sulfur utilization and specific capacity. [Display omitted] [ABSTRACT FROM AUTHOR]

Precise regulation of pore sizes and fouling issues related to filter cake formation and bacterial growth continue to impede the practical application of GOMs. Though metal-organic frameworks (MOFs) with specific structures and semiconductor features are a potential candidate for addressing the above issues, it is still difficult to accurately control the GOM pore with MOFs, due to the difficulty of removing interfacial gaps. In this study, we successfully employed the specific pore size of HKUST-1 (Cu-BTC, BTC: benzene-1,3,5-tricarboxylate) to control the channel size of GOMs by self-assembling a pH-regulated HKUST-1/GO dispersion, followed by moderate- to high-temperature vacuum drying. Consequently, the incorporation of HKUST-1 dramatically influenced the rejection performance of GOMs, enabling the selective rejection of molecules larger than 9 Å (e.g., Rh B, CV, and TB) while effectively separating sub-9 Å impurities (e.g., MB and NaCl), and resulting in a nearly 14-fold increase in water flux. Moreover, the photodegradation and Cu2+ release properties of HKUST-1 endowed the GO@HKUST-1 membrane (GHM) with remarkable self-cleaning, antibacterial and long-term stable characteristics. Our approach provides a simple and universal method for conferring GOM with accurate size-sieving, self-cleaning, and antibacterial multi-functionalities, thereby enabling high-quality and sustainable molecular separation and dye desalination. Strategy of intercalating HKUST-1 to endow GOM with accurate size-sieving, self-cleaning and antibacterial multi-functions. [Display omitted] • GHM pore is successfully controlled by excluding the GO/MOF interfacial gaps. • 9 Å-sized frameworks make GHM with accurate selectivity and high permeability. • HKUST-1 also confers GOM with self-cleaning and antibacterial multi-functions. [ABSTRACT FROM AUTHOR]

• A semi-rigid and self-supporting electrode was prepared by an easy electroplating. • The semi-rigid electrode can be adjusted with different shapes. • The catalytic properties for HER can be remained even shaped as an "S". • The preparation steps were friendly and it can be easily fabricated in a factory. • The detailed mechanism for such self-supporting electrode was investigated. The self-supporting catalytic electrode is useful in the industry, since it can reduce the complex pre-treatment of catalytic materials and avoid the use of binders. In this work, a ternary self-supporting electrode including Cu mesh-supported graphene and molybdenum disulfide (MoS 2) was prepared by electroplating zinc and hydrothermal reaction. Due to the excellent conductivity of copper and the hydrogen evolution catalytic ability of MoS 2 , this self-supporting electrode showed a low Tafel slope as 54 mV dec−1 and a current density of 400 mA cm−2 at an overpotential of -300 mV in hydrogen evolution reaction (HER). In addition, due to the metal flexibility of the Cu mesh substrate, the MoS 2 –rGO Cu ternary self-supporting electrode can be bent or cut into any desired shape. Even shaped as an elongated one, curved "S", this self-supporting electrode still kept itself from any deformation when hydrogen bubbles were rapidly generated. Therefore, a strategy for green, simple, and low-cost self-supporting electrode was provided, which may increase the large-scale operation of the catalytic electrode in HER. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Interconnected three-dimension (3D) networks of novel helical carbon nanotubes (HCNTs) wrapped with reduced graphene oxide nanosheets (HCNTs/rGO) are successfully fabricated via a facile solution of self-assembly method, as well as a robust process for the simultaneous reduction and high N-doping of HCNTs/rGO composites (N-HCNTs/rGO) by photoreduction under NH 3 atmosphere. The as-prepared N-HCNTs/rGO are directly employed as binder-free supercapacitor electrodes, and exhibit a highly conductive 3D-interconnected structure (5.85 S cm −1 ), large surface area (528.9 m 2  g −1 ), low internal resistance (0.5 Ω), and good wettability. As a result, N-HCNTs/rGO show high specific capacitance (368 F g −1 ), high energy density (12.8 Wh kg −1 ), and cycling stability (90.7% retention at 1 A g −1 for 5000 cycles) in two-electrode systems. Moreover, the 3D N-HCNTs/rGO hybrid networks exhibit enhanced electrochemical performance in supercapacitors, which combine the synergistic effects of the two carbon nanostructures, enhanced wettability, low internal resistance, and improved ion-diffusion ability, together with the large surface areas of 3D hybrid networks and high-level N-doping. The as-synthesized composite is a potential candidate for flexible and binder-free electrodes for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Nitrogen-enriched graphene was fabricated via a facile strategy. Graphene oxide (GO) nanosheets and graphene oxide quantum dots (GQDs) were used as a structure-directing agent and in situ activating agent, respectively, after photoreduction under NH 3 atmosphere. The combination of photoreduction and NH 3 not only reduced GO and GQD composites (GO/GQDs) within a shorter duration but also doped a high level of nitrogen on the composites (NrGO/GQDs). The nitrogen content of NrGO/GQDs reached as high as 18.86 at% within 5 min of irradiation. Benefiting from the nitrogen-enriched GO/GQDs hybrid structure, GQDs effectively prevent the agglomeration of GO sheets and increased the numbers of ion channels in the material. Meanwhile, the high levels of nitrogen improved electrical conductivity and strengthened the binding energy between GQD and GO sheets. Compared with reduced GO and low nitrogen-doped reduced GO, NrGO/GQD electrodes exhibited better electrochemical characteristics with a high specific capacitance of 344 F g −1 at a current density of 0.25 A g −1 . Moreover, the NrGO/GQD electrodes exhibited 82% capacitance retention after 3000 cycles at a current density of 0.8 A g −1 in 6 M KOH electrolyte. More importantly, the NrGO/GQD electrodes deliver a high energy density of 43 Wh kg −1 at a power density of 417 W kg −1 in 1 M Li 2 SO 4 electrolyte. The nitrogen-doped graphene and corresponding supercapacitor presented in this study are novel materials with potential applications in advanced energy storage systems. [ABSTRACT FROM AUTHOR]

• PTZ/rGO composite is prepared under hydrothermal condition. • PTZ/rGO composite can produce pseudocapacitance via redox reaction related to PTZ. • PTZ/rGO composite exhibits higher discharge specific capacity than rGO. • PTZ/rGO cathode-based LIC shows high energy density and good cyclic stability. The specific capacity of cathode in lithium-ion capacitors is greatly lower than that of anode, resulting in the energy density of device is limited. In this work, to enhance the specific capacity of cathode, redox-active phenothiazine is introduced and a superior-performance phenothiazine/reduced graphene oxide composite cathode is synthesized under hydrothermal condition. Owing to the production of pseudocapacitance by phenothiazine, the optimized composite cathode can give rise to higher discharge specific capacity (86.6 mAh g–1 under 0.5 A g–1) than reduced graphene oxide cathode (36.2 mAh g–1), even though the lower specific surface area. In addition, outstanding cyclic performance is presented by this composite cathode with capacity retention ability of 80.4% at the end of 700 cycles in Li-half cell under 0.5 A g–1. Furthermore, when paired with a carbon tube anode, the constructed lithium-ion capacitor possesses a larger energy density (114.4–17.8 Wh kg–1) than the device (57.0–1.9 Wh kg–1) without phenothiazine in the cathode. And it is found that the introduction of phenothiazine doesn't decrease the power density of device. Additionally, this composite cathode based device has good cycling stability with capacity fade ratio as low as 12.7% even after 8000 cycles. [Display omitted] The introduction of redox-reactive phenothiazine which can produce pseudocapacitance into the rGO-based cathode of Li-ion capacitor results in the enhanced energy density of device. [ABSTRACT FROM AUTHOR]

The structures and rheological properties of three different plate-like particle suspensions, i.e., organically-modified montmorillonite (OMMT), graphene oxide (GO) and Kaolinite (Kaolin) in silicone oil (SO), are explored. Since the interactions between plate-like particle and SO are different, the dispersion states of these particles in SO are different. OMMT particles disperse relatively well in SO, and small clusters exist in GO/SO suspensions, but larger aggregates are found in Kaolin/SO suspensions. Moreover, liquid-crystalline ordering structure is found in both OMMT/SO and GO/SO suspensions, while it is absent in Kaolin/SO suspensions. Negative normal stress differences (Δ N ) are observed during shear in all three plate-like particle suspensions, however, the mechanisms of the negative Δ N might be different. It can be further inferred that the negative Δ N in OMMT/SO suspensions results from the tumbling and rotating motions of OMMT sheets, while for GO/SO or Kaolin/SO suspensions, the negative Δ N results from the vorticity alignment of large GO clusters and Kaolin aggregates. [ABSTRACT FROM AUTHOR]

The structure and rheological properties of graphene oxide (GO)/polydimethylsiloxane (PDMS) composites are examined as the molecular weight of PDMS and concentration of GO are varied. Clusters formed by GO sheets get smaller and disperse better with increasing molecular weight of PDMS, which results in the higher critical concentration to form network ( C cr ). Moreover, at GO concentration just above C cr , the plateau modulus of samples decreases with the molecular weight of PDMS. During shear experiments, negative normal stress differences (Δ N ) are observed in composites with PDMS molecular weight lower than critical entanglement molecular weight ( M c ). However, positive Δ N is found in samples with PDMS molecular weight above M c . It can be concluded that the vorticity alignment of GO clusters induces the negative Δ N based on the optical shear experiments. The possible mechanism for the positive Δ N is also proposed. [ABSTRACT FROM AUTHOR]

Graphene oxide membranes (GOMs) have great potentials in the high-performance desalination of salty wastewater. However, the low-selectivity and fouling issues are the main obstacles to practical implementation. Although compositing with TiO 2 nanoparticles alleviates such problems by regulating membrane structures and photodegrading surface organic filter cakes, the performance is still limited by the intrinsic aggregation feature and narrow UV response range. Here, we functionalize TiO 2 nanoparticles with polypyrrole (PPy) to improve their dispersibility and visible-light-driven photodegradation properties. The as-formed core-shell heterostructures (PPy@TiO 2) with a large dose are intercalated into GOM, resulting in a large water flux (436.93 Lm−2h−1bar−1) and selective positive dye/negative dye separation with a maximum salt permeation of 97%. Upon the reduction of the dosage, more than 99% of dyes are separated regardless of molecule weights and surface charge polarity although the average water flux is reduced to 5.83 Lm−2h−1bar−1 and the salt rejection rate is increased up to 24%. In addition, the composite membrane with low-dosed PPy@TiO 2 photodegrades MB completely within 2 h, while its water permeability and dye rejection performance are maintained after a 5 h filtration process. Our work provides a facile method to develop multi-functional 2D composite membranes with controllable and stable dye desalination performances. [Display omitted] • The incorporation of PPy improves the dispersibility of TiO 2 nanoparticles in GOMs. • The core-shell PPy@TiO 2 enables GOMs with high dye/salt and dye/dye selectivity. • The PPy@TiO 2 induces the visible-light-driven self-cleaning capability of GOMs. • The PPy@TiO 2 makes GOM with ultra-high water permeability. [ABSTRACT FROM AUTHOR]

• The optical property of CsPbX 3 QDs is extremely sensitive to the electron injection. • One electron in a 10 nm-sized QD will bring forth an electron density of ~1018 cm−3. • It is the first time to observe B-M effect arisin from electron transfer. As an ultrathin transport layer, graphene-based materials play an increasingly important role in perovskite optoelectronics. Full comprehension of the carrier transfer process between them is of great significance, however, seldom attention has been paid to how the carrier transfer, from graphene derivative to perovskite, affects the physical property of perovskite. Here, we report that CsPbBr 3 and CsPbI 3 QDs produce a Burstein-Moss type photoluminescence (PL) blueshift arisen from the electron transfer from graphene oxide (GO), and in CsPbI 3 QDs this effect is highly notable, ~50 meV. Such results indicate that perovskite QDs is highly optically sensitive to the electron injection, and quite promising in optoelectronic modulator applications. [ABSTRACT FROM AUTHOR]

The rapid development of flexible and portable electronics has brought great opportunities to develop flexible and lightweight energy-storage systems. Herein, a free-standing, mechanically flexible and binder-free three-dimensional (3D) sandwich-type network film electrode with reduced graphene oxide (RGO)-wrapped helical carbon nanotubes (HCNT) is designed and synthesized by a synergistic and applicable self-assembly strategy. HCNT in the composites serve as the inner skeleton, impede the stacking of RGO and enlarge the space between RGO effectively, which facilitate the creation of conductive 3D architectures and reinforce the structural stability. Moreover, the RGO coating and the voids are beneficial in improving electrochemical conductivity. As a result, the as-prepared RGO/HCNT electrodes show excellent electrochemical characteristics, yielding the specific capacitances of 336 F g−1 at a current density of 0.25 A g−1, and it offers the energy density of 7.5 Wh kg−1 with the corresponding power density of 100 W kg−1 as well as excellent cycling stability at approximately 89.5% capacitance retention exceeding 3000 cycles. The bending tests indicate that the flexible supercapacitors (SCs) can operate under different static bending angles, and the capacitance is hardly affected. The HCNT and corresponding flexible SCs are novel materials with potential applications in the next generation of wearable energy devices. [ABSTRACT FROM AUTHOR]

Poly(diallyldimethylammonium chloride)-functionalized reduced graphene oxide (PDDA-rGO) nanomaterials are fabricated by a facile ultrasonic blending method at room temperature and proposed as anodic electrocatalyst for microbial fuel cells (MFCs). PDDA serves as a noncovalent p-type dopant with strong electron-withdrawing ability, which is beneficial to readily attract electrons and further accelerate the rate of extracellular electron-transfer (EET) from the electrochemical active bacteria to the anode. Additionally, introduction of polyelectrolyte PDDA greatly increases the electroactive area and intensifies the biocompatibility of the anode. The electrochemical active microorganisms are effectively accumulated and a stable biofilm is rapidly formed. These factors result in the reduction of internal resistance and significantly enhance the power generation for MFCs, with the largest power density of 5029.3 mW m−2 (corresponding current density 11822.6 mA m−2), which is 2.51-fold and 5.46-fold of the unfunctionalized reduced graphene oxide (rGO) and bare carbon paper (CP) anodes, respectively. A facile preparation of anode materials at room temperature and the characteristics of remarkable biocurrent generation exhibit positive implication for the development of high performance MFCs. Image 1 • PDDA-rGO prepared by sonication at room temperature for MFCs anode. • Synergistic promotion of catalytic carbon sites and reaction kinetics. • Further facilitation for the rate of EET. • Obtaining a promoted power density over 2.51-fold of rGO and 5.46-fold of CP. [ABSTRACT FROM AUTHOR]