rGO Nanosheets Research Articles

Electrochemical study of an enhanced platform by electrochemical synthesis of three-dimensional polyaniline nanofibers/reduced graphene oxide thin films for diverse applications

This work reports the electrochemical fabrication of thin films comprising polyaniline nanofibers (PANI) in conjunction with graphene oxide (GO) and reduced graphene oxide (rGO) on ITO substrate, along with examining the electrochemical properties, with a focus on the influence of the substrate and electrolyte in the electrodeposition methods. The study explores the electrochemical characteristics of these thin films and establishes a flexible framework for their application in diverse sectors such as sensors, supercapacitors, and electronic devices. It analyzes the impact of the substrate and electrolyte in electrodeposition techniques. The effects were studied using techniques such as cyclic voltammetry and chronoamperometry. The fabrication process of PANI/GO and PANI/rGO thin films involved the integration of rGO within PANI via electropolymerization, conducted under sulfuric acid. GO was synthesized by modifying the well-known Hummers’ method and characterized by X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). SEM showed the diameters of the formed PANI were between 40 and 150 nm, which helped to intertwine the rGO nanosheets with PANI nanofibers to form thin films. The electrochemical behavior of the PANI/rGO thin films was examined using cyclic voltammetry (CV) and chronoamperometry in different electrolytes, including sulfuric acid (H₂SO₄) and potassium nitrate (KNO₃). The CV profiles exhibited distinct oxidation and reduction peaks, with variations in the voltammogram morphology attributed to the nature of the electrolyte and the substrate employed during the electrodeposition process. These results highlight the critical role of both the substrate and electrolyte in governing the electrochemical performance of PANI/rGO thin films. The findings from this study demonstrate a versatile approach for the fabrication of PANI/graphene-based thin films with tunable electrochemical properties, and such a strategy has great application to fabricating other thin film composites for supercapacitors or other control source frameworks requiring enhanced charge storage and electrochemical responsiveness.

Fabrication of rGO-Bridged TiO2/g-C3N4 Z-Scheme Nanocomposites via Pulsed Laser Ablation for Efficient Photocatalytic CO2 Reduction.

Highly efficient photocatalysts can be fabricated using favorable charge transfer nanocomposite channel structures. This study adopted pulsed laser ablation in liquid (PLAL) to obtain rGO-bridged TiO2/g-C3N4 (rGO-TiO2/g-C3N4) photocatalytic Z-scheme without the need for noble metals. In addition to evaluating the resulting nanocomposite (comprising rGO nanosheets, TiO2 nanotubes, and g-C3N4 nanosheets) CO2 reduction effectiveness, its chemical, morphological, structural, and optical characteristics were examined using various analytical techniques. The findings revealed a synergistic interaction between g-C3N4 and TiO2, suggesting the presence of unique interfacial bonding, as well as enhanced visible light absorption. Notably, the ternary rGO-TiO2/g-C3N4 Z-scheme exhibits an excellent photocatalytic performance by photocatalytically converting CO2 into CO and CH4, with 81 % selectivity towards the CO and 1.91 % apparent quantum efficiency at 420 nm. Thus, the findings can pave the way for various Z-scheme systems in wide photocatalytic applications.

Synthesis and characterizations of SrMnO3 with rGO nanosheets (SMO-rGO) in energy-related applications

Synthesis and characterizations of SrMnO3 with rGO nanosheets (SMO-rGO) in energy-related applications

In-situ synthesis of bifunctional N-doped CoFe₂O₄/rGO composites for enhanced electrocatalysis in hydrogen and oxygen evolution reactions

The development of cost-effective and efficient materials for electrochemical water splitting using non-noble metal oxide is a promising strategy to promote clean energy and mitigate environmental issues. In this study, we synthesized N-doped CoFe2O4 (NCF) and various wt% rGO-loaded N-doped CoFe2O4 (x = 1 %, 3 %, and 5 %; denoted as NCFRx) using a hydrothermal method. Subsequently, the NCF and NCFR3 samples were annealed at four different temperatures (y = 550, 600, 650, and 700 °C; denoted as NCFR3-y). FE-SEM, TEM, and XPS studies revealed a strong interface between rGO nanosheets and N-doped CF, acting as electron transport carriers that enhance performance in hydrogen and oxygen evolution reactions (HER and OER). The electrochemical evaluation of the prepared materials was carried out in a 1.0 M KOH electrolyte. The nickel foam (NF) electrode supported by the NCFR3–650 composite demonstrated excellent and stable electrocatalytic performance with a minimum overpotential of 73 mV and 170 mV at a current density of 10 mA/cm2 for HER and OER, respectively, and achieved excellent faradaic efficiencies of 91.01 % for OER and 90.48 % for HER. These results confirmed that the NCFR3–650@NF composite catalyst was comparable to standard Pt/C and IrO2, exhibiting lower overpotential and Tafel slope at a current density of 10 mA/cm2. The double layer capacitance (Cdl) of NCFR3–650@NF (7.70 mF/cm2) was higher than that of other electrocatalysts, indicating a large electrochemically active surface area. The structural properties of NCFR3–650@NF contributed to improved stability during long-term HER and OER analysis. Therefore, the developed NCFR3–650@NF electrocatalyst is a promising alternative to noble metal-centered systems for water splitting, offering overall high efficiency.

A New Powerful Magnetic Dark Catalyst Based on rGO/Fe3O4/CdSe Nanocomposite for Ultrafast Degradation of Methylene Blue Dye.

In the present study, Rgo/Fe3O4/CdSe as a dark catalyst material was synthesized by a refluxing method. The synthesized magnetic nanocomposites were studied by various analyses such as Fourier transform infrared (FTIR), energy-dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (FESEM), X-ray diffractometer (XRD), Raman, Zeta and vibrating sample magnetometer (VSM). Characterization of structural analysis showed that the nanocomposites were successfully synthesized. The absorption spectrum was used to determine the dark catalyst activity of rGO/Fe3O4/CdSe nanocomposite. Analysis of the absorption spectrum showed that the prepared nanocomposites degrade the MB organic dye completely (100%) after 2min of stirring in the dark, also experimenting with different pH showed that the best performance for the degradation of MB occurs in neutral and alkaline media. The Raman spectrum analysis showed that the Fe3O4/CdSe quantum dots (QDs) were correctly incorporated on the reduced graphene oxide (rGO) nanosheets. Zeta potential analysis showed that rGO/Fe3O4/CdSe has a large amount of negative charge on its surface and the surface charge increased by about 16 mV compared to the Fe3O4/CdSe compound. BET and BJH techniques were used to determine the effective surface area and pore size diameter, BET results to determine the effective surface area showed that by adding graphene to the compound, the specific surface area increased from 42.877 m2g-1 to 54.1896 m2g-1. The radical scavenger experiment showed that electrons play an essential role in the degradation process. VSM analysis showed that the prepared nanocomposites have excellent superparamagnetic behavior, this advantage enables the easy collection of nanocatalysts by magnets from wastewater after dye degradation.

Visible Light-Triggered Catalytic Performance of Reduced Graphene Oxide Decorated With Copper Oxide Nanocomposite for Degradation of Rhodamine B Dye and Kinetics Studies.

Herein, novel nanocomposites based on reduced graphene oxide decorated copper oxide nanoparticles (rGO/CuO) were prepared by the in situ co-precipitation method. The structural, morphological, and optical characterization of as-prepared nanocomposites was performed by powdered x-ray diffraction (p-XRD), scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR), Raman, and ultraviolet-visible (UV-Vis) spectroscopy, respectively. The as-prepared nanocomposites exhibited better photocatalytic activity of rhodamine B dye with maximum ~94% degradation in 120 min with a rate constant of 0.2353 min-1 under optimized conditions. Furthermore, the effects of solution pH and catalyst loading are studied on the degradation process. Therefore, this state-of-the-art strategy for the decoration of CuO nanoparticles onto the surface of rGO nanosheets could be an ideal platform for fabricating highly efficient photocatalysts.

In-situ exfoliating graphene to anchor Mo2C NPs and modulate crystal planes for hydrogen production

An economical and efficient noble metal-free catalyst is necessary for large-scale hydrogen production. Here, Mo2C nanoparticles (NPs) were well-dispersed on the surface of 2D graphene nanosheets by in-situ propping oxide graphene (GO) layers, anchoring molybdate ions between GO layers and pyrolysis. The exposed crystal planes were also adjusted by above strategy. The results indicate that uniform and well-dispersed Mo2C NPs with a narrow size distribution were anchored on 2D rGO nanosheets and exposed dual crystal planes. The results of hydrogen evolution reaction (HER) show that the optimal Mo2C/rGO catalyst only needs low overpotential (η10, 112 mV) to drive 10 mA cm−2 in alkaline solution, and η10 only increased by 12 mV after 1000 cycles test, indicating high activity and stability for HER. Notably, the overpotential is below than that of Pt/C commercial catalyst when current density is more than 100 mA cm−1. The excellent performance is benefit from low hydrogen adsorption Gibbs free energy (ΔGH∗) on the Mo2C catalyst. Therefore, the proposed strategy is efficient to prepare well-dispersed and dual crystal planes-exposed Mo2C NPs for electrocatalytic hydrogen evolution.

High-performance NF-loaded F-NiFe-LDH/rGO nanoflower/nanosheet composite electrode material achieving enhanced specific capacitance and energy density for supercapacitor

High-performance nanostructured F-NiFe-LDH/rGO composite electrode materials with F-NiFe-LDH nanoflowers and rGO nanosheets are synthesized in a controlled hydrothermal method by leveraging the strong synergistic effects between the components, enabling the construction of F-NiFe-LDH/rGO//AC asymmetric supercapacitors. The incorporation of rGO significantly enhances electron transport, resulting in an exceptional specific capacitance of 2860 F g−1 at a current density of 1 A g−1, with a remarkable capacity retention of 102 % after 1000 cycles. This represents a notable improvement in electrochemical energy storage, with surface-controlled capacitance contributing more in alkaline electrolytes for F-NiFe-LDH/rGO composite compared to F-NiFe-LDH alone. The asymmetric supercapacitor device exhibits a specific capacitance of 354 F g−1 at 1 A g−1, maintaining 92.31 % of its initial capacitance after 1000 charge/discharge cycles at 5 A g−1, and achieves an impressive energy density of 110 Wh kg−1 at 1 A g−1. The innovation of this work lies in the controllable preparation of nanostructured F-NiFe-LDH-rGO supercapacitor electrode material with enhanced specific capacitance and energy density by the synergistic effect between F-NiFe-LDH and rGO. This work offers a solid foundation for creating high-performance supercapacitor electrode materials and devices for energy storage applications.

Synergistic photocatalytic and antibacterial efficacies of Ag/rGO and Ag/Ag2O/rGO nanocomposites: The impact of oxide formation and ternary heterojunction

This study explores the efficient solvothermal integration of Ag/rGO and Ag/Ag2O/rGO nanocomposites using various solvents and employs thorough characterization procedures. The primary focus is on understanding the nuanced effects resulting from the combination of Ag nanoparticles with rGO nanosheets, particularly in the context of Ag2O formation. For a quantitative assessment of their photocatalytic and antibacterial properties, graphene oxide and silver nitrate (AgNO3) were introduced to create Ag/rGO and Ag/Ag2O/rGO nanocomposites. The results demonstrate a significant enhancement in photocatalytic performance for the Ag/Ag2O/rGO nanocomposite, achieving a rapid degradation of 99.99 % of methylene blue dye within 30 minutes under simulated solar light irradiation. This heightened efficiency is attributed to improved separation and transfer efficiency, as well as the substantial generation of photoinduced carriers due to the incorporation of visibly active Ag2O nanoparticles. Moreover, the Ag/Ag2O/rGO nanocomposite exhibits an enhanced antibacterial activity, reflected in Minimum Inhibitory Concentration (MIC) values of 50 μg/ml for Bacillus cereus and 300 μg/ml for Escherichia coli. The nanocomposite's higher antimicrobial activity against Gram-positive bacteria, particularly Bacillus cereus, is underscored, revealing its potential as an effective antibacterial agent. The formation of a ternary heterojunction in the Ag/Ag2O/rGO nanocomposite results in a notable increase in the production of free radicals, enhancing charge carrier migration and separation efficiency. This quantitative evidence emphasizes the versatile nature of the nanocomposite, highlighting its potential across diverse fields through augmented antibacterial and photocatalytic properties.

Graphene-Wrapped Magnetic Multichamber Ti3C2Tx Spheres for Stable Broadband Microwave Absorption.

Two-dimensional transition metal carbides/nitrides (MXenes) have aroused widespread interest in the field of microwave absorption because of their unique layered structures. However, the inherent aggregation, poor impedance matching, and low chemical stability of MXenes inevitably obstruct their practical applications. Herein, a multichamber Fe3O4/Ti3C2Tx@reduced graphene oxide (FT@RGO) hierarchical structure was constructed through self-assembly and sacrificial template strategies where the Ti3C2Tx nanosheets were assembled into hollow microspheres that were decorated with Fe3O4 nanospheres and wrapped by RGO nanosheets. The massive heterointerfaces and interior cavities favor enhanced microwave absorption performance via interfacial polarization, multiple scattering/reflections, and dielectric-magnetic synergistic effects. Consequently, the synthesized ultralight FT@RGO foam (0.009 g/cm3) presents superior microwave absorption ability with the minimum reflection loss of -50.5 dB at the matching thickness of 2.5 mm and effective absorption bandwidth of 8.0 GHz covering the frequency range of 10.0-18.0 GHz at the thickness of 2 mm. Furthermore, the encapsulation of hollow Ti3C2Tx spheres by RGO nanosheets avoids direct contact with external air, which considerably improves the stability of Ti3C2Tx and ensures the long-term application of FT@RGO foam in a conventional environment. This work provides a reference for the structural design of MXene-based materials as broadband and durable microwave absorbers.

Hollow Cobalt Selenide-Carbon polyhedron sandwiched between reduced graphene oxide nanosheets: A superior anode material for lithium-ion batteries

In this work, a double carbon-confined sandwich-like CoSe/NCP/rGO composite was fabricated using an self-assembled method combined with a selenization treatment. In the composite, cobalt selenide (CoSe) nanoparticles were embedded in N‑doped hollow carbon polyhedrons (NCP) and sandwiched between reduced graphene oxide (rGO) nanosheets. The kinetics of electron/ion transport along with the structural stability of the composite were significantly enhanced by the layer-by-layer sandwiched hollow structure and the strong cohesive interface interaction between various components. The CoSe/NCP/rGO, when serving as LIB’s anode material, exhibited excellent performance. It demonstrated a high specific capacity with the value of 843 mAh/g at 1 A/g, superior high-rate capability with capacity remaining at 309 mAh/g at 10 A/g, long-term cycling stability with no noticeable capability fading over 1000 loops. More importantly, these results were achieved without additional conductive agents.

Fabrication of NbTe2@rGO nanosheet by hydrothermal route for cost-effective supercapacitor electrode

The expansion of energy storage devices with extensive stability and high energy density is a crucial area of research that requires immediate attention. In light of these requirements, it was worth noting that supercapacitor (SCs) exhibit great potential as viable options for achieving these demands. Supercapacitor (SCs) despite their potential currently exhibit energy density levels that fall short of the necessary threshold for long-term applications. This limitation primarily stems from the challenge of identifying the ideal materials to enhance their performance. However, transition metal tellurides have a well-studied group of materials that have garnered noticeable consideration because of high energy density. Herein, we present a novel hydrothermal method that involves the fabrication of reduced graphene oxide (rGO) nanosheet combined with niobium telluride (NbTe2) material. However, the NbTe2@rGO nanohybrid's specific capacitance (Csp) was 1475 F g−1, which was approximately twice as high as the specific capacitance of the NbTe2 (667 F g−1) electrode with a specific capacity of 826 C/g at 1 A g−1 which could be ascribed to interconnection between nanoparticles and nanosheets in the NbTe2@rGO nanohybrid with lower Rct = 0.02 Ω and outstanding cycling stability even after undergoing 7000th cycles with a capacitance retention of (97 %). The NbTe2@rGO nanohybrid demonstrated an impressive power density of 285 W kg−1 and energy density of 22 Wh kg−1 at 1 A g−1 in its symmetric two-electrode performance. The findings of this investigation suggested that NbTe2@rGO nanohybrid exhibits promising material for future energy storing devices.

Anchoration of hydrothermally developed FeSe nanoparticles on rGO nanosheets as electrode for energy storage devices

A perpetual discrepancy exists between demand and supply due to the inherent fluctuation of renewable energy sources. A possible approach for addressing this persistent issue involves the advancement of appropriate materials for consumption in energy storage systems. An example of a device that can potentially serve as energy storage is a supercapacitor equipped with highly effective electrode materials. This study synthesizes FeSe, rGO and FeSe@rGO electrodes via hydrothermal route. Specific capacitance (Cs) of FeSe, rGO and FeSe@rGO electrode was measured by GCD analysis as 517, 799, and 1408 F g−1 at 1 A g−1. The synthesized FeSe@rGO nanohybrid exhibits outstanding performance and high cycling stability up to 10000th cycles. Furthermore, the enhanced supercapacitance of the nanohybrid has been ascribed to the synergistic interaction between FeSe and rGO, which delivers higher surface area and enhanced active sites. Further, symmetric two-electrode study revealed excellent electrode material with specific capacitance (Cs) of 553 at 1 A g−1 with capacitive retention of 66.36 % after 1000th cycle. However, the electrochemical investigation demonstrated that the FeSe@rGO nanohybrid structure exhibited superior performance and could be used in different electrochemical applications.

Construction of 2D/1D rGO/H2Ti3O7 composite as anode for high performance lithium-ion batteries

Ultrafine one-dimensional (1D) H2Ti3O7 nanowires were prepared by a hydrothermal reaction with high concentration of KOH as base source. Then 2D/1D rGO/H2Ti3O7 architecture was constructed and investigated as the anode material for lithium-ion batteries. Benefiting from the addition of rGO nanosheets and the retention of ultrafine 1D H2Ti3O7 nanowires, the rGO/H2Ti3O7 electrode presented superior electrochemical performance with excellent rate capability, long cycling stability and high capacity in half cells. It delivered high reversible capacities of 274 mAh g−1 at 0.1 A g−1 and 163 mAh g−1 at 1 A g−1, as well as a long-term cycling performance (259.3 mAh g−1 at 0.2 A g−1 after 1000 cycles). The excellent electrochemical performance of the composite can be attributed to the unique architecture with smaller diameter of 1D H2Ti3O7 nanowires and conductive rGO nanosheets to shorten the transmission distance of electrons and Li+ and improve the electrical conductivity in rGO/H2Ti3O7 composite.

Iron nanoparticles supported on graphene nanosheets by pulsed laser ablation method in deionized water

In this study, pulsed laser ablation process (PLA) in deionized water solution was used to prepare graphene oxide (GO) nanosheets, wustite (FeO) nanoparticles and GO based FeO nanoparticles. The effect of composition ratio of materials on their optical properties was studied. The structural properties of the materials were characterized using transmission electron microscopy (TEM) and x-ray diffraction (XRD) techniques. According to the TEM results, FeO nanoparticles were well deposited on GO nanosheets. The XRD results demonstrated the formation of Fe and wustite (FeO) phase of iron oxide nanoparticles. In the XRD analysis of graphene sample, graphene oxide (GO) and reduced graphene oxide (rGO) nanosheets were identified. The absorption measurement of the samples in colloidal state was performed using a UV–vis single beam spectrophotometer in the wavelength range of 250 to 800 nm. The higher and the lower absorbance belonged to 1.4 ml GO − 0.6 ml FeO composition and GO nanosheets, respectively. The linear optical properties of the samples, including the real and imaginary parts of the dielectric function, refractive index, extinction coefficient and absorption coefficient were calculated using the spectroscopic ellipsometry (SE) method. Leng oscillator was used as the optical model in SE method. Also, the energy band gap of the samples was calculated using Tauc relation, in which the lower and the higher energy band gaps were obtained for GO nanosheets (3.40 eV) and FeO nanoparticles (4.65 eV), respectively. Furthermore, the nonlinear optical properties of GO based FeO nanoparticles were investigated by Z-scan measurement. The nonlinear refractive index and nonlinear absorption coefficient were obtained in the order of 10−8 cm2 W−1 and 10–4 cm W−1, respectively.

Corrosion behavior of ternary HA-NrGO-CS composite coatings via cathodic electrophoretic deposited on ZK60 Mg alloy combining with thermal annealing

In this paper, effect of various contents of chitosan (1.0, 1.5 and 2.0 wt%) on corrosion/degradation behavior of ternary HA-NrGO-CS prepared on ZK60 alloy substrates were investigated. The samples were prepared by combining cathodic electrophoretic deposition and thermal argon atmosphere annealing for 120 min at 200 °C to regulate corrosion and quick degradation of ZK60 Mg alloy surface. After immersion for 30 min, HA-NrGO-1.5CS coated sample exhibited highest |Z|0.1Hz value, trailed by the HA-NrGO-2.0CS, HA-NrGO-1.0CS and ZK60 alloy samples. After immersion for 2 days, |Z|0.1Hz values moved to higher Bode modulus for HA-NrGO-CS coated samples, indicating poles and defects were filled due to the formation of apatite layer on the HA-NrGO-CS surface. FT-IR and Raman spectra proved the successful doping of N atoms into the rGO nanosheet skeleton to form NrGO. The SEM images and EDS plane-scan results for the samples after immersion for 2 days verified the existence of an apatite layer. The experimental results indicated that the existence of CS, HA and NrGO in the composite coatings can regulate the pH values and supply a sustained release of Mg2+ ions and O2 due to the synergistic effect of the protonation/deprotonation of -NH2 groups in CS and the dissolution/recrystallization of HA. Furthermore, the production of MgO2 film can convert corrosion behavior of ZK60 alloy from pitting corrosion to uniform corrosion, which provided a potential strategy for bone biomedical applications.

Microwave-assisted synthesis of perovskite hydroxide-derived Co3O4/SnO2/reduced graphene oxide nanocomposites for advanced hybrid supercapacitor devices

The current article reports a facile, ultrafast, and cost-effective, solid-state microwave (MW) synthetic route for the conversion of perovskite hydroxide (CoSn(OH)6) to crystalline metal oxides (Co3O4 and SnO2) with the help of reduced graphene oxide (rGO) nanosheets. In a domestic MW oven, the Co3O4/SnO2/rGO (CSO-rGO) nanocomposite was synthesized within a quick reaction time of only 30 s. The study deeply focused on analyzing the surface morphology, metal oxide attachment on the surfaces of rGO nanosheets, the specific surface area, and the electrochemical performance of supercapacitor devices from the CSO-rGO nanocomposite. As a positive electrode for supercapacitors, the synthesized hybrid electrode displayed a good capacity (146.4C/g) and enhanced cycling stability (103.2 % after 15,000 cycles). Moreover, the corresponding aqueous hybrid supercapacitor device with MW-synthesized rGO as a negative electrode displayed a maximum energy density of 27 Wh/kg and promising cycling stability of 102.4 % after 10,000 cycles. As a whole, compared to the common time-consuming synthetic approaches, the MW-assisted synthetic approach is highly beneficial in terms of short reaction time, cost-effectiveness, and straightforwardness. The MW synthesis methodology employed in this study can be utilized for analogous composite electrodes that incorporate other layered conductive architectures in addition to metal oxides.

Recycling of reduced graphene oxide from graphite rods in disposable zinc battery applicable to optical sensing

We report a low cost, simple method to fabricate reduced graphene oxide (rGO) optical sensors from recycled batteries. The rGO nanosheets were exfoliated by electrochemical method under the assistant of electric arc using 5 % KOH or NaOH electrolytes. The rGO nanosheets show interlayer distances ranging from 3.98 to 6.22 Å, and thicknesses from 0.62 to 6.00 nm, corresponding from 1 to 10 layers, respectively, determined from X-ray diffraction (XRD), atomic force microscopy (AFM), and transmission electron microscopy (TEM) measurements. Selected area electron diffraction (SAED) measurement indicates that rGO nanosheets content Miller-Bravais indices of (1–210) and (0–110) planes, and the hexagonal diffraction pattern of (0–110) plane of graphene sheets with d-spacing of 2.13 Å. Low defect densities in exfoliated rGO nanosheets were confirmed by ID/IG ratios ∼0.16 to 0.18 via Raman. The rGO nanosheets exfoliated in NaOH electrolyte have 19.35 % lower oxygen content compared to those exfoliated in KOH electrolyte inspected from XPS spectra. The performance of the rGO optical sensors is controlled by defects created from oxygen functional groups formed during exfoliation process. The responsivity and response (rise) time of NaOH-exfoliated rGO sensor are 0.46 A/W and 2.3 s, respectively. These values are 21 % (for responsivity) larger and 35 % (for rise time) smaller than those of KOH-exfoliated rGO sensor. The best-in-class of high gain were demonstrated in this study for the rGO optical sensors prepared from disposed graphite rods. The results demonstrate how disposed batteries can be recycled to produce photodetectors and other optoelectronic devices using cheap and relatively nontoxic methods.

Interface coupling of octahedron Cu2O with reduced graphene oxide for enhanced photocatalytic and photoelectrochemical activity

Graphene oxide (GO) has been recognized as an ideal substrate material of semiconductor photocatalysts to achieve superior properties. Herein, Cu2O/reduced graphene oxide hetero-structures (Cu2O/rGO), featured by octahedron Cu2O with highly exposed {111} facets in-situ anchored on the framework of rGO nanosheets, were constructed via a green wet chemistry route at room temperature. During the reactions, Cu2+ ions that were adsorbed on GO could act as the nucleation sites of Cu2O while GO was further converted into rGO under the reduction of glucose, forming a robust hetero-interface of C–O–Cu bonding. Owning to the improved photon capture ability and carrier separation efficiency, the optimized Cu2O/rGO exhibits about 3.5 and 9.3 times enhancement of photocurrent intensity and photocatalytic activity, respectively, as compared to those of pure Cu2O. Meanwhile, the correlation among rGO content, structure and photocatalytic activity of Cu2O/rGO was demonstrated. This work presents a rational route and deep insight for the interface coupling within metal oxide/carbon material hetero-structures for advanced catalytic applications.

Rigid-flexible coupling multistage carbon composite materials based on hybrid crosslinking as anodes for ultra long-cycling lithium-ion batteries

Graphene have garnered considerable attention owing to their disordered structure, wide layer spacing, and cost-effectiveness. The hierarchical porous structure of porous reduced graphene oxide (rGO) nanosheets with hollow carbon nanospheres offers advantages such as an intact conductive network and a robust structure. However, since the hollow carbon nanospheres are physically in contact with rGO, they are randomly dispersed on the graphene surface, severely impeding fast electron transport and resulting in poor electrochemical performance. In this study, we introduced a third layer of a polypyrrole (PPy) -derived carbon film on the basis of porous rGO sheets and hollow carbon nanospheres. The HCGP-200 anode was successfully prepared to effectively encapsulate hollow carbon nanospheres on rGO sheets through the synergistic effect of rGO and the PPy-derived carbon film. The HCGP-200 anode exhibits robust cycling performance (780 mAh g−1 after 2200 cycles at 5 A g−1) and excellent rate capacity. Additionally, it demonstrates outstanding cycling stability and remarkable capacity retention (450 mAh g−1 after 3000 cycles) even at ultra-high current densities of 20 A g−1. The ingenious design and preparation of HCGP-200 is of great significance in guiding the application of high-power appliances.