Reduced Graphene Oxide Anode Research Articles

Ultrafine VN quantum dots modified with a nitrogen-doped reduced graphene oxide anode material for enhanced rate capability and lifespan of lithium-ion batteries

The excellent electrochemistry performance is attributed to vanadium nitride quantum dots (VNQDs) offering large capacity and nitrogen-doped reduced graphene oxide (NrGO) acting as a conductive network and buffer skeleton.

Photosynthetic Efficiency of Microalgae and Cyanobacteria on Reduced Graphene Oxide (RGO) Anode Surface for Utilization in Bio-Photovoltaics (BPV)

Bio-photovoltaics (BPV) is sustainable energy production technology that utilize photosynthetic organisms and convert it into electricity. This Study has been carried out to study the photosynthetic efficiency of three microalgae on a Reduced Graphene Oxide (RGO) anode surface. RGO, with its exceptional electrical conductivity and large surface area, presents an attractive platform for enhancing the performance of BPV systems. The work aims to investigate the combined effect of microalgae and RGO anodes for use in BPV technology. RGO was synthesized and characterized on which Chlorella vulgaris, Gloeocapsa and Synechocystis were allowed to grow. A model BPV system was assembled, incorporating the microalgae and cyanobacteria as photoactive agents and RGO as the anode surface. The system was subjected to different experimental condition and photosynthetic efficiency, current generation, and power output were collected and analysed. Results demonstrated a significant improvement in the photosynthetic activity of microalgae when cultured on the RGO anode surface. Chlorella Shows maximum Efficiency in terms of growth and current generation. Statistical analysis confirmed the reliability and significance of these findings. Our finding bridges a crucial knowledge gap in the field of BPV, highlighting the potential of microalgae-RGO systems for cleaner energy production.

Cost effective synthesis hetero-structured N-doped C-coated Ni9S8/Ni3S2/NiS1.03 nanoparticles attached on 3D reduced graphene oxide anode to exceptional Li-ion performance

In this study, nitrogen all-doped carbon-coated Ni9S8/Ni3S2/NiS1.03 (NixSy) particles with homogeneous bonds to 3D reduced graphene oxide sheets (N-NixSy@C/G) were synthesized via a using the facile hydrothermal, freeze-drying and subsequent calcination method. In this structure, the carbon layer derived from glucose was highly uniformly dispersed in an Ar atmosphere, such that the structural stability is enhanced and the volume expansion of NixSy is effectively mitigated. The Ni9S8, Ni3S2 and NiS1.03 nanoparticles were formed effectively facilitated under the existence of glucose. In situ nitrogen doping was achieved by the presence of urea containing nitrogen, such as electron conductivity was increased and fast ion intercalation was facilitated. The structural stability and cyclability can be ensured for the high flexibility and structural strength of the reduced graphene oxide wrapping layer. Under the synergistic effect exerted by the three modules, N-NixSy@C/G was further endowed with high electrical conductivity, large specific surface area as well as abundant electrochemical reaction sites. On that basis, the N-NixSy@C/G anode that was employed in the lithium-ion batteries exhibited superior rate capability and ultra-high reversible capacity (826.3 mAh g−1 at 0.5 A g−1). The capacity was kept at 703 mAh g−1 and the coulombic efficiency reached 100% after 1000 cycles at a current density of 2 A g−1. This study may contribute to the creation of a distinctive avenue for designing quick and high-capacity metal sulfide anodes and boost the growth of high-performance lithium batteries.

Superior cycling stability of saturated graphitic carbon nitride in hydrogel reduced graphene oxide anode for Sodium-ion battery

A layered composite g-C3N4@RGO of graphitic carbon nitride (g-C3N4) and reduced graphene oxide (RGO) is reported as an anode material for rechargeable sodium ion batteries (SIBs). Initially, conducting interconnected hydrogel RGO was prepared by hydrothermal method and was further soaked in saturated urea solution, followed by calcination to synthesize g-C3N4@RGO composites. The coin type half cells were prepared by using composite g-C3N4@RGO and pristine RGO as anode and their electrochemical performances were compared. The prepared half-cell of the composite anode delivers maximum reversible specific discharge capacity of ∼ 170 mAh.g−1 and ∼ 160 mAh.g−1 at 0.1C and at 0.2C, respectively. Whereas, prepared half-cell using RGO anode shows maximum reversible discharge capacity of ∼ 146 mAh.g−1 and ∼ 133 mAh.g-1at 0.1C and 0.2C, respectively. This composite material g-C3N4@RGO shows excellent cyclability (2000 cycles) and columbic efficiency ∼ 100% with no capacity fading compared to the RGO. The binding of g-C3N4 with RGO prevents stacking of RGO sheets and provides macro and sub-micron porous structure for smooth intercalation and trapping of Na+-ions in composite g-C3N4@RGO anode during electrochemical cycling. The design of g-C3N4@RGO composite as a negative electrode improves the cell performance and offers effective strategy to develop low-cost and long cycle life SIBs.

Synthesis of Homogeneous Hollow Co3O4 Microspheres for Enhanced Cycle Life and Electrochemical Energy Storage Performance

AbstractHow to achieve a balance between excellent pseudocapacitive performance and simplicity of the synthetic pathway of Co3O4 is still a challenge. Herein, hollow Co3O4 microspheres were synthesized through a facile template‐free solvothermal approach with a following calcination treatment. The synthetic Co3O4 exhibited remarkable electrochemical properties in terms of high specific capacity 922.7 F g−1 at 1 A g−1, superior rate capability with 67.7 % capacitance retention (1–20 A g−1), as well as excellent cycling stability (105.6 % retention after 10000 cycles). A hybrid supercapacitor device is also successfully assembled consisting of a Co3O4 cathode and a reduced graphene oxide anode with a wide potential window of 0–1.65 V, which delivers a high energy density and an outstanding cycle lifetime. These superior electrochemical properties will render the hollow Co3O4 microsphere material as an attractive material for promising application in high‐performance electrochemical energy storage systems.

Hollow cobalt oxide nanoparticles embedded porous reduced graphene oxide anode for high performance lithium ion batteries

Hollow cobalt oxide nanoparticles embedded porous reduced graphene oxide hybrids are constructed by means of a facile etching strategy and the Kirkendall effect. When examined as an anode for lithium-ion batteries, this unique structured composite exhibits remarkable lithium storage capability such as excellent rate capability, superior reversible specific capacity together with good cycling durability, highlighting the importance of embedding active materials on graphene sheets for maximum utilization of hollow structured cobalt oxide and porous reduced graphene oxide for energy devices.

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

AbstractLithium‐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.

Carbon riveted Pt-MnO2/reduced graphene oxide anode catalyst for DMFC

Low activity and poor stability of catalyst has been the issue for the commercialization of DMFC. We introduced MnO2 as co-catalyst and used graphene as support for Pt nanoparticles. In situ carbonization using l-ascorbic acid as carbon source was further employed to boost the performance of the catalyst, where the carbon riveted Pt-MnO2/reduced graphene oxide prepared (PMGL) not only showed larger electrochemical surface area and better catalytic activity towards methanol oxidation, but also revealed stronger ability to resist CO poisoning and better stability than Pt-MnO2/rGO and Pt/rGO catalysts. The improvement of catalyst performance can be attributed to synergistic effects developed between MnO2 and Pt and the anchoring effect of l-ascorbic acid, as suggested by HR-TEM/EDX and XPS characterization studies.

Novel iodine-doped reduced graphene oxide anode for sodium ion batteries

It is reported for the first time that iodine-doped reduced graphene oxide (I-rGO) has been designed as an anode material for sodium ion batteries (SIBs).

A high-voltage lithium-ion battery prepared using a Sn-decorated reduced graphene oxide anode and a LiNi0.5Mn1.5O4 cathode

This paper describes the preparation and characterization of a high-voltage lithium-ion battery based on Sn-decorated reduced graphene oxide and LiNi0.5Mn1.5O4 as the anode and cathode active materials, respectively. The Sn-decorated reduced graphene oxide is prepared using a microwave-assisted hydrothermal synthesis method followed by reduction at high temperature of a mixture of (C6H5)2SnCl2 and graphene oxide. The so-obtained anode material is characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, and electron diffraction spectroscopy. The LiNi0.5Mn1.5O4 is a commercially available product. The two materials are used to prepare composite electrodes, and their electrochemical properties are investigated by galvanostatic charge/discharge cycles at various current densities in lithium cells. The electrodes are then used to assemble a high-voltage lithium-ion cell, and the cell is tested to evaluate its performance as a function of discharge rate and cycle number.

The synthesis of polypyrrole@Mn3O4/reduced graphene oxide anode with improved coulombic efficiency

A two-step method consisting of an in-situ transformation and an in-situ oxidative polymerization is employed to fabricate polypyrrole@Mn3O4/reduced graphene oxide composites. The resulting materials are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and Raman. The XRD analysis reveals the formation of Mn3O4/reduced graphene oxide and polypyrrole@Mn3O4/reduced graphene oxide. Mn3O4 particles coated with reduced graphene oxide and polypyrrole get an average diameter of ca.27nm. The TEM images of polypyrrole@Mn3O4/reduced graphene oxide demonstrate that Mn3O4/reduced graphene oxide nanocomposites are indeed coated by a transparent polypyrrole film. The FT-IR studies disclose the characteristic functional groups between the respective materials. Moreover, Raman measurements confirm the reduction of graphite oxide to reduced graphene oxide. The result of electrochemical measurement demonstrates that it gets a high initial discharge capacity of ca.1600mAhg−1 at 60mAg−1 and the initial charge/discharge efficiency delivers a nice optimization after coated with polypyrrole (ca.45% VS ca.70%). The capacity of polypyrrole@Mn3O4/reduced graphene oxide can maintain at a level of ca.1000mAhg−1 in the first five cycles and the rate performance of it is much better than that of Mn3O4/graphene.

Porous Li4Ti5O12/ Reduced Graphene Oxide Anode Materials with Enhanced Rate Capability and Cyclability

Li4Ti5O12 (LTO) is one of the most promising anode materials for lithium-ion batteries. Besides its advantages of near-zero volume change, solid electrolyte interface free, and high thermal stability, further improvement of its performance is hindered by the intrinsic electronic insulating property of LTO. Graphene is an excellent additive to improve electrode performance due to its high conductivity, large surface area and chemical stability. In this study, porous LTO/reduced graphen oxide (rGO) composite thin films were prepared by electrostatic spray deposition (ESD). Graphen oxide sheets used in precursor were readily reduced to rGO during the ESD deposition. The electrochemical performance was characterized by cyclic voltammetry (CV) and galvanostatic charge-discharge. Our results reveal that the LTO electrodes exhibit high rate capability and long cycle life. In the potential range of 0.05-3 V, the LTO electrode delivers reversible specific capacity of 274，257, 240, 202, 158 and 106 mAh g-1 at different current rates of 0.5 C, 1 C, 2 C, 5 C, 10 C and 20 C, respectively. After high C rate test, the electrode was tested at 2 C for 100 cycles. No capacity decay was observed even after testing at harsh condition. Detailed results will be presented in the meeting.

Free-Standing Nitrogen-Doped Reduced Graphene Oxide Anode for Lithium-Ion Batteries

Graphenes have been considered suitable candidate materials for electrodes of energy storage devices such as lithium-ion batteries (LIBs) because of their outstanding mechanical, thermal and electrical properties. However, there are problems when using these carbon materials for electrodes because of their low electrochemical performance. In this work, to improve the electrochemical performances of graphenes, free-standing nitrogen-doped reduced graphene oxides (FNRGOs) were prepared as an anode for LIBs using a facile vacuum filtration method and thermal annealing at different temperatures. X-ray diffraction and X-ray photoelectron spectroscopy were employed to characterize the prepared samples, and then their electrochemical performance was investigated by galvanostatic charge/discharge (GCD) tests. GCD tests revealed that FNRGO prepared from thermal annealing at 500 degrees C exhibited good initial reversible capacity (502 mA h/g at 50 mA/g (0.14 C)) and enhanced cycle stability (capacity retention of 90.5% after 50th cycles at 100 mA/g (0.27 C), which demonstrated that FNRGOs were suitable candidates as anodes for LIBs.

A Novel High‐Energy Hybrid Supercapacitor with an Anatase TiO2–Reduced Graphene Oxide Anode and an Activated Carbon Cathode

AbstractA hybrid supercapacitor with high energy and power densities is reported. It comprises a composite anode of anatase TiO2 and reduced graphene oxide and an activated carbon cathode in a non‐aqueous electrolyte. While intercalation compounds can provide high energy typically at the expense of power, the anatase TiO2 nanoparticles are able to sustain both high energy and power in the hybrid supercapacitor. At a voltage range from 1.0 to 3.0 V, 42 W h kg−1 of energy is achieved at 800 W kg−1. Even at a 4‐s charge/discharge rate, an energy density as high as 8.9 W h kg−1 can be retained. The high energy and power of this hybrid supercapacitor bridges the gap between conventional batteries with high energy and low power and supercapacitors with high power and low energy.

Reduced graphene oxide with superior cycling stability and rate capability for sodium storage

Sodium ion battery is a promising electrical energy storage system for sustainable energy storage applications due to the abundance of sodium resources and their low cost. In this communication, the electrochemical properties of sodium ion storage in reduced graphene oxide (RGO) were studied in an electrolyte consisting of 1M NaClO4 in propylene carbonate (PC). The experimental results show that the RGO anode allowed significant sodium ion insertion, leading to higher capacity at high current density compared to the previously reported results for carbon materials. This is due to the fact that RGO possesses higher electrical conductivity and is a more active host, with large interlayer distances and a disordered structure, enabling it to store a higher amount of Na ions. RGO anode exhibits high capacity combined with long-term cycling stability at high current densities, leading to reversible capacity as high as 174.3mAhg−1 at 0.2C (40mAg−1), and even 93.3mAhg−1 at 1C (200mAg−1) after 250 cycles. Furthermore, RGO could yield a high capacity of 141mAhg−1 at 0.2C (40mAg−1) over 1000 cycles.

Organic solar cells using a reduced graphene oxide anode buffer layer

We report on a solution processed reduced graphene oxide (rGO) thin films as anode buffer layer in organic solar cells. The spin-coated rGO, and zinc oxide (ZnO) thin films have been used to fabricate bulk heterojunction organic solar cells employing [poly({4,8-di(2-ethylhexyloxyl)benzo[1,2-b:4,5-b′]dithiophene}-2,6-diyl)-alt-({5-octythieno[3,4-c]pyrrole-4,6-dione}-1,3-diyl):fullerene (PBDTTPD:PCBM) blends as a photoactive layer. Atomic force microscopy, X-ray diffraction, UV–vis absorption spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and photovoltaic measurements were performed to investigate the morphology, materials of processed thin films, and device performance of the fabricated devices. The ZnO also plays an important role in blocking holes, collecting electrons and serves as conducting channels to the cathode top electrode. A short-circuit current density (Jsc) and fill factor (FF), increase when the rGO was introduced, which directly contributed to the improved efficiency to 4.8%.

High energy density asymmetric supercapacitors with a nickel oxide nanoflake cathode and a 3D reduced graphene oxide anode

Here we demonstrate a high energy density asymmetric supercapacitor with nickel oxide nanoflake arrays as the cathode and reduced graphene oxide as the anode. Nickel oxide nanoflake arrays were synthesized on a flexible carbon cloth substrate using a seed-mediated hydrothermal method. The reduced graphene oxide sheets were deposited on three-dimensional (3D) nickel foam by hydrothermal treatment of nickel foam in graphene oxide solution. The nanostructured electrodes provide a large effective surface area. The asymmetric supercapacitor device operates with a voltage of 1.7 V and achieved a remarkable areal capacitance of 248 mF cm(-2) (specific capacitance of 50 F g(-1)) at a charge/discharge current density of 1 mA cm(-2) and a maximum energy density of 39.9 W h kg(-1) (based on the total mass of active materials of 5.0 mg). Furthermore, the device showed an excellent charge/discharge cycling performance in 1.0 M KOH electrolyte at a current density of 5 mA cm(-2), with a capacitance retention of 95% after 3000 cycles.