MnO₂ Nanoflowers Deposited on Graphene Paper as Electrode Materials for Supercapacitors

Abstract

We recently reported a simple and cost-effective green method to produce free-standing, flexible, and highly conductive electrochemically exfoliated graphene paper (GrP) for a supercapacitor application. To improve the capacitance behavior of GrP, manganese dioxide (MnO2) was electrochemically deposited on GrP with different number of MnO2 cycles. After the electrochemical deposition process, MnO2 nanoflowers were formed, which provide a fast transfer of electrolyte ions. After 10 cycles of electrodeposition, MnO2-coated GrP (GrP/10-MnO2, which is the optimal composition) exhibited an excellent capacitive performance with a high specific capacitance of 385.2 F·g–1 at 1 mV·s–1 in 0.1 M Na2SO4 electrolyte and outstanding capacitance retention after 5000 consecutive cycles. Taking advantage of both superior mechanical and capacitance behavior of GrP and GrP/10-MnO2 electrodes, a flexible solid-state asymmetric supercapacitor (SASc) device was assembled using GrP/10-MnO2 and GrP as positive and negative electrode, respectively. The fabricated SASc device exhibited not only high areal capacitances of 76.8 mF cm–2 at a current density of 0.05 mA cm–2 but also excellent cycling stability of 82.2% after 5000 consecutive galvanostatic charge/discharge cycles. This flexible supercapacitor can also deliver a high energy density of 6.14 mWh·cm–2 with a power density of 36 mW·cm–2. This research represents a new direction for exploring the potential of free-standing GrP and its nanocomposites in flexible energy-storage systems.

Advances on Emerging Materials for Flexible Supercapacitors: Current Trends and Beyond

“…With no surprise, the PET was a substrate to connect the electrochemically deposited MnO 2 graphene paper assembled to be the working electrode. [ 149 ] Here, the Mn precursor was also oxidized by a simple step of converting the Mn 2+ ions exhibited a very good capacitance. The bending angles were also tested up to 180° at 0.05 mA cm –2 and with the increase in current density decline in the cycles could be observed.…”

Uncovering the origin of enhanced field emission properties of rGO–MnO2heterostructures: a synergistic experimental and computational investigation

“…The formation of rGO-MnO 2 nanostructures and their electrochemical performance have been extensively investigated and it was demonstrated that compared to the single metal-oxide, rGO/MnO 2 nanocomposites show superior electric conductivity, electric capacity and charge/ discharge efficiency for supercapacitor performance. [29][30][31][32][33][34] These characteristics make rGO/metal-oxide nanocomposites promising materials for energy applications. Considering that eld emission is geometry (shape, size, aspect ratio, alignment, and areal density of the nanostructure) and work function dependent phenomenon, well-aligned rGO/MnO 2 nanostructures is promising for enhancement of eld emission characteristics.…”

An electrochemically exfoliated graphene/poly(3,4-ethylenedioxythiophene) nanocomposite-based electrochemical sensor for the detection of nicotine

“…GR was prepared by an electrochemical exfoliation method. 50,51 Briefly, graphite sheets (3 cm  0.5 cm) were used as electrodes. Graphite sheets (B1.5 cm length of both the anode and cathode) were dipped into 50 mL of 0.1 M PBS (pH 7) for 30 min, and +10 V was supplied using a DC power supply (Model: 2231A-30-3, Keithley, a Tektronix company, USA).…”