The synthesis of shape-controlled MnO2/graphene composites via a facile one-step hydrothermal method and their application in supercapacitors

Abstract

Novel MnO 2 petal nanosheet and nanorod/graphene composites are successfully fabricated by a facile one-step hydrothermal method through changing the content of the Mn source. The formation mechanism of different morphologies of MnO 2 /graphene composites have been studied. The structure of the MnO 2 /graphene is "sandwich"-like, with MnO 2 petal nanosheets and nanorods homogeneously anchored on each side of the graphene. Furthermore, the MnO 2 /graphene composites with different shapes can be used for supercapacitor electrode materials. The experimental results show that the MnO 2 petal nanosheet/graphene composite has better capacitance performance than that of the MnO 2 nanorod/graphene composite. The MnO 2 petal nanosheet/graphene composite shows excellent specific capacitance as high as 516.8 F g À1 at a scan rate of 1 mV s À1 in 1 M Na 2 SO 4 electrolyte and good longterm cycle stability, indicating its potential application to act as a promising electrode material for highperformance supercapacitors. This study provides a facile and in situ method to prepare metal oxide/ graphene composite materials and a novel scaffold to construct other metal oxides with graphene for energy storage.

Flexible all-solid-state micro-supercapacitor based on Ni fiber electrode coated with MnO2 and reduced graphene oxide via electrochemical deposition

“…By comparison, the intensities of these absorption peaks are dramatically decreased in rGO, suggesting that most of oxygen-containing groups have been removed via electrochemical reduction. For MnO 2 / rGO, a strong and wide absorption peaks appears around 525 cm −1 , corresponding to the Mn-O vibrations of MnO 2 [12]. Fig.…”

“…Carbon materials, such as activated carbon [6], carbon nanotubes (CNTs) [7] and graphene [8,9], are normally used as electrode materials in EDLCs while conducting polymers and metal oxides/hydroxides in pseudo-capacitors. Among metal oxides/hydroxides (e.g., RuO 2 , MnO 2 , Co 3 O 4 , Ni(OH) 2 ) [10][11][12][13][14], MnO 2 is one of the most attractive materials because of its high theoretical pseudo-capacitance, low cost and environmental compatibility [4,[15][16][17].…”

An amperometric glucose biosensor based on a MnO2/graphene composite modified electrode

“…Until now, composites of GR/MnO 2 with various morphologies have been synthesized, including nanoparticles, nanowires, nanosheets, spheres and hollow spheres, nanobelts, unchinlike and so on. 21,[37][38][39][40][41][42] These composites showed excellent electrochemical properties and have been mainly used in supercapacitors. However, there have been few reports on their application in biosensors.…”

“…According to the report, GO was highly negatively charged due to the large amounts of oxygen-containing functional groups on the surface and edges of the GO nanosheets. 21 In the reaction solution of synthesizing the composite, Mn 2+ was adsorbed on the surface and edges of the GO by electrostatic forces and then oxidized by oxidant. The chemical reaction involved in the synthesis of MnO 2 and the composite is as follows:…”

Hydrazine Sensor Based on Co3O4/rGO/Carbon Cloth Electrochemical Electrode

“…[ 11 ] Although, lots of materials (such as zinc oxide nanonails, [ 12 ] ZnO nanorods, [ 13 ] polypyrrole nanoplates, [ 14 ] etc.) have been used in electrochemical sensors, exploring an effi cient and sensitive electrode material is of vital importance.In the past few decades, carbon-based composites, such as epoxy/carbon fi ber, [ 15 ] MnO 2 /graphene, [ 16 ] graphene oxide (GO)/ Fe, [ 17 ] MHTiO 2 @C-Au, [ 18 ] and Ni(OH) 2 /3D graphene, [ 19 ] have attracted tremendous interests owning to their unique physical and chemical properties. Specially, carbon cloth (CC) composites, consisting of reinforcing carbon fi bers and functional nanomaterials, are widely used in microwave absorption, [ 20 ] catalysis, [ 21,22 ] and supercapacitors, [ 23,24 ] due to its excellent mechanical strength, good corrosion resistance, high electrical conductivity, excellent fl exibility, and low-cost.…”