Functionalization of Biomass Carbonaceous Aerogels: Selective Preparation of MnO₂@CA Composites for Supercapacitors

Abstract

Functionalized porous carbon materials with hierarchical structure and developed porosity coming from natural and renewable biomass have been attracting tremendous attention recently. In this work, we present a facile and scalable method to synthesize MnO2 loaded carbonaceous aerogel (MnO2@CA) composites via the hydrothermal carbonaceous (HTC) process. We employ two reaction systems of the mixed metal ion precursors to study the optimal selective adsorption and further reaction of MnO2 precursor on CA. Our experimental results show that the system containing KMnO4 and Na2S2O3·5H2O exhibits better electrochemical properties compared with the reaction system of MnSO4·H2O and (NH4)2S2O8. For the former, the obtained MnO2@CA displays the specific capacitance of 123.5 F·g(-1). The enhanced supercapacitance of MnO2@CA nanocomposites could be ascribed to both electrochemical contributions of the loaded MnO2 nanoparticles and the porous structure of three-dimensional carbonaceous aerogels. This study not only indicates that it is vital for the reaction systems to match with porous carbonaceous materials, but also offers a new fabrication strategy to prepare lightweight and high-performance materials that can be used in energy storage devices.

Oil tea shell derived porous carbon with an extremely large specific surface area and modification with MnO2 for high-performance supercapacitor electrodes

“…The graphitic structure carbons might have originated from the bio-waste carbon source. After carbonization, the layer structures in the oil tea shell were inherited in the micro-structures of AC particles [33][34][35][36] . The microstructures were studied using the SEM and TEM, at low magnification (Figure 1c), the carbon particles had flake shapes; at high magnification (Figure 1d), the layered structures were clearly observed at the edge of the particles.…”

Carbon Aerogels Derived from Bacterial Cellulose/Polyimide Composites as Versatile Adsorbents and Supercapacitor Electrodes

“…[6] Carbon aerogels consisting of one-dimensional carbon nanofibers with high aspectr atio are extremely intriguing for their unique aligned and intersected structures, [7,8] which satisfyingly provide maximized adsorptive and conductivep roperties.R ecently,c arbon nanofiber aerogels derived from carbonaceous nanofiber monolithic hydrogels wereo btained through the combination of template-directed hydrothermalc arbonization method, freeze drying technique and pyrolysis process, showing interconnected three-dimensional network structures with high sorptionc apacities toward variouso ils and organic solvents. [9] However,t he fabrication processes not only bring potential environmental risks with the usage of sodium tellurite,b ut also are limited for mass production.B iomass, such as watermelon, [10] winter melon, [11] bagasse, [12] and plant cellulose, [13,14] on the other hand, has drawn great interest because of the rich reserves, renewability,a nd nontoxicity.S un et al synthesized porous carbon aerogels from renewable biomass waste of coconut shells via an easy and cost-effective simultaneous activationgraphitization route, [15] which providess hort ion-diffusion channels for energy-storage devicesa ttributed to their unique two-dimensional graphene-likes tructures. Nevertheless,t he complicated composition of coconuts hells, including cellulose, lignin,a nd pentosan, makes them hardly qualified as raw materials for further usages.…”

Mixed-Phase MnO2/N-Containing Graphene Composites Applied as Electrode Active Materials for Flexible Asymmetric Solid-State Supercapacitors

“…The line tail connecting the semicircle at the low-frequency region is associated with the ionic diffusion resistance, a thermodynamic-controlled process. The equivalent circuit for the EIS analysis is also depicted in Figure 7 , which includes [ 73 ]: (1) the charge transfer impedance in the high-frequency region at the electrode/electrolyte interface (R CT ), (2) the solution resistance (R S ), which is the contact series resistance between the substrate and current collector, (3) Warburg impedance (W), which is the diffusion resistance of ions in the electrolyte and in relation to the slope of the line tail in the low-frequency region, (4) the electric double-layer capacitor (C 1 ) [ 65 , 74 , 75 , 76 ]. The corresponding R CT values obtained by simulation are listed in Table 1 .…”