scholarly journals Effect of Potassium Ions on the Formation of Mixed-Valence Manganese Oxide/Graphene Nanocomposites

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1245 ◽  
Author(s):  
Wooree Jang ◽  
Dae-Young Jeon ◽  
Youn-Sik Lee ◽  
Hye Young Koo
Keyword(s):  
Graphene Oxide ◽  
Manganese Oxide ◽  
Mixed Valence ◽  
High Specific Capacitance ◽  
Potassium Ions ◽  
Electrochemical Supercapacitors ◽  
One Pot ◽  
Graphene Nanocomposites ◽  
Reduced Graphene ◽  
A Current

One-pot synthesis of mixed-valence manganese oxide (MnOx)/potassium ion-doped reduced graphene oxide (rGO) composites for efficient electrochemical supercapacitors is introduced. Using manganese nitrate and potassium permanganate as co-precursors for the MnOx and by directly annealing the rGO without tedious purification steps, as described herein, MnOx/rGO composites with a high specific capacitance of 1955.6 F g−1 at a current density of 1 A g−1 are achieved. It is found that the presence of potassium ions helps in the development of mixed-valence MnOx on the surface of the rGO.

A reduced graphene oxide/mixed-valence manganese oxide composite electrode for tailorable and surface mountable supercapacitors with high capacitance and super-long life

2017 ◽  
Vol 10 (4) ◽  
pp. 941-949 ◽  
Author(s):  
Yang Wang ◽  
Wenhui Lai ◽  
Ni Wang ◽  
Zhi Jiang ◽  
Xuanyu Wang ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Manganese Oxide ◽  
Reduced Graphene Oxide ◽  
Composite Electrode ◽  
Mixed Valence ◽  
High Capacitance ◽  
Oxide Composite ◽  
Reduced Graphene ◽  
Long Life ◽  
Electrode Fabrication

The rGO/MnOx composite is compatible with the slurry dispensing process for electrode fabrication, and can exhibit super-long life property.

One-pot hydrothermal synthesis of polyaniline nanofibers/reduced graphene oxide nanocomposites and their supercapacitive properties

2019 ◽  
Vol 31 (9-10) ◽  
pp. 1238-1247 ◽  
Author(s):  
Shanxin Xiong ◽  
Yuancheng Wang ◽  
Jia Chu ◽  
Xiaoqin Wang ◽  
Runlan Zhang ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Specific Capacitance ◽  
Current Density ◽  
Electrochemical Performances ◽  
One Pot ◽  
Raman Analysis ◽  
Polyaniline Nanofibers ◽  
Reduced Graphene ◽  
A Current ◽  
Charge Discharge

In this article, polyaniline nanofibers/reduced graphene oxide (PANI-NFs/rGO) nanocomposites were prepared by a one-pot hydrothermal method. Under the condition of high temperature and high pressure, graphene oxide (GO) was reduced to rGO and aniline was in-situ polymerized to form PANI-NFs using ammonium persulfate as oxidant. The morphologies and structures of PANI-NFs/rGO nanocomposites were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and Raman analysis. The results show that PANI-NFs uniformly grow on the surfaces of rGO sheets, which can act as spacers to prevent the aggregation of rGO. Combining with FTIR and Raman analysis, it can be concluded that PANI-NFs/rGO nanocomposites are successfully prepared. The electrochemical performances of PANI-NFs/rGO nanocomposites were tested by cyclic voltammetry and galvanostatic charge–discharge. The PANI-NFs/rGO nanocomposites exhibit superior electrochemical performances compared to the PANI-NFs. With 10 wt% of GO loaded, the PANI-NFs/rGO nanocomposite exhibits highest specific capacitance of 942 F g−1 at a current density of 1 A g−1. The PANI-NFs/rGO nanocomposites also demonstrate good rate capacity and high cycling stability under the high discharging current density (10 A g−1), the specific capacitance can still reach to 680 F g−1. After 1000 charge–discharge cycling at a current density of 5 A g−1, 78% of specific capacitance can be retained. The enhanced capacitive performances can be attributed to the facile electron conduction pathway brought by the even distribution of highly conductive rGO nanosheets.

Performance of Fast Thermally Reduced Graphene Oxide for Supercapacitor

2013 ◽  
Vol 785-786 ◽  
pp. 783-786 ◽  
Author(s):  
Hong Juan Wang ◽  
Dong Zhou ◽  
Feng Peng ◽  
Hao Yu
Keyword(s):  
Graphene Oxide ◽  
Specific Capacitance ◽  
Reduced Graphene Oxide ◽  
Current Density ◽  
High Specific Capacitance ◽  
Thermal Reduction ◽  
Exfoliated Graphite ◽  
Capacitive Performance ◽  
Reduced Graphene ◽  
A Current

Graphene with different reduction degrees was prepared by fast thermally reduction of exfoliated graphite oxide (GO) at 200-700 °C. Structure and the electrochemical capacitive performance were characterized and measured. The results show that different thermal reduction temperatures can obtain reduced graphene oxide (rGO) with different reduction degrees and influence the electrochemical capacitive performance. The rGO-400 by thermal treat at 400 °C exhibits a significantly high specific capacitance of 407 F g-1 in 6.0 M KOH electrolyte at a current density of 0.4 A g-1 and outstanding cyclic stability with 96.1% of its origin specific capacitance maintained after 2000 cycles at the current density of 10 A g-1 in GCD test.

scholarly journals Defect-Rich Heterogeneous MoS2/rGO/NiS Nanocomposite for Efficient pH-Universal Hydrogen Evolution

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 662 ◽  
Author(s):  
Guangsheng Liu ◽  
Kunyapat Thummavichai ◽  
Xuefeng Lv ◽  
Wenting Chen ◽  
Tingjun Lin ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Active Sites ◽  
Reduced Graphene ◽  
Heterogeneous Interfaces ◽  
Wide Ph Range ◽  
Ph Range ◽  
A Current ◽  
Poor Stability

Molybdenum disulfide (MoS2) has been universally demonstrated to be an effective electrocatalytic catalyst for hydrogen evolution reaction (HER). However, the low conductivity, few active sites and poor stability of MoS2-based electrocatalysts hinder its hydrogen evolution performance in a wide pH range. The introduction of other metal phases and carbon materials can create rich interfaces and defects to enhance the activity and stability of the catalyst. Herein, a new defect-rich heterogeneous ternary nanocomposite consisted of MoS2, NiS and reduced graphene oxide (rGO) are synthesized using ultrathin αNi(OH)2 nanowires as the nickel source. The MoS2/rGO/NiS-5 of optimal formulation in 0.5 M H2SO4, 1.0 M KOH and 1.0 M PBS only requires 152, 169 and 209 mV of overpotential to achieve a current density of 10 mA cm−2 (denoted as η10), respectively. The excellent HER performance of the MoS2/rGO/NiS-5 electrocatalyst can be ascribed to the synergistic effect of abundant heterogeneous interfaces in MoS2/rGO/NiS, expanded interlayer spacings, and the addition of high conductivity graphene oxide. The method reported here can provide a new idea for catalyst with Ni-Mo heterojunction, pH-universal and inexpensive hydrogen evolution reaction electrocatalyst.

One-pot hydrothermal synthesis of Ag-reduced graphene oxide composite with ionic liquid

2011 ◽  
Vol 21 (21) ◽  
pp. 7795 ◽  
Author(s):  
Jianfeng Shen ◽  
Min Shi ◽  
Bo Yan ◽  
Hongwei Ma ◽  
Na Li ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Graphene Oxide ◽  
Hydrothermal Synthesis ◽  
Reduced Graphene Oxide ◽  
One Pot ◽  
Oxide Composite ◽  
Reduced Graphene
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