Abstract
Since porous carbon materials derived from biomass, with low cost, abundant and sustainable, relatively easy fabrication, high electrical conductivity, large specific surface area (SSA), surface morphology with nanomaterial structures, and superior electrochemical stability have attracted attention which are strong and highly trusted to be a candidate for the electrode material of supercapacitor energy storage. This study highlighted recent laboratory-scale methods for preparing activated carbon nanostructures from leaves biomass wastes. Four types of focused leaves waste including acacia leaves, pineapple leaves, and Terminalia catappa leaves (TCL), and Pandanus tectorius leaves (PTL). Leave wastes were converted into activated carbon by KOH activation and one-stage integrated pyrolysis both of carbonization and physical activation. Symmetric supercapacitor electrode ware performed with sandwich-type in monolith form without adhesive materials. Among the raw materials found in this study, nanofiber structures dominated the surface morphology of carbon monolith, especially in acacia leaves, pineapple leaves, and TCL. Interestingly, the same basic material of TCL could perform two different nanostructures including nanofiber and nanosheet. In addition, the percentages of carbon and oxygen contents in the sample were also provided. Furthermore, supercapacitor cells exhibited the highest specific capacitance are activated carbon derived from pineapple leaves as high as 150 F g−1 in 1M H2SO4 aqueous electrolyte at a low scanning rate of 1 mV s−1. Finally, these results confirmed that leaves biomass wastes have high potential as a raw material of activated carbon nanofiber/nanosheet structure to be applied in supercapacitor electrodes.
Highlights
The activated carbon nanostructures with various morphologies have attracted attention due to their superior physical and chemical properties for applications such as supercapacitors [1], batteries, catalysis, and sensors
The results of this review indicate the high potential of leaf waste to produce nanostructured activated carbon with a more efficient and effective method for supercapacitor electrode material
Surface morphology is the main review for evaluating nanostructures on activated carbon monoliths for supercapacitor electrodes
Summary
The activated carbon nanostructures with various morphologies have attracted attention due to their superior physical and chemical properties for applications such as supercapacitors [1], batteries , catalysis, and sensors. The biggest source of activated carbon material is biomass due to high lignocellulose compound which including hemicellulose, cellulose, and lignin [4]. The basic components of plant biomass including cellulose, hemicellulose, lignin, plant protein, plant lipids offer a basic skeleton structure and abundant functional groups for the carbons. Biomass is converted to activated carbon through several steps such as carbonization, chemical activation, and physical activation, or a combination of all three [5,6]. These steps could decompose cellulose, hemicellulose, and lignin and evaporate volatile compounds to produce fixed carbon
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