Synergistic electrochemical performance of textile sludge based activated carbon with reduced graphene oxide as electrode for supercapacitor application

Abstract

The procedure for disposing of textile waste sludge requires sustainable solutions due to numerous environmental issues associated with its disposal. The majority of textile manufacturers incinerate the waste sludge to meet their heating demands, which is harmful to the environment. It can also be used in soil amendment, biodegradable products, construction material and water treatment process as absorbent to remove the heavy metals etc. In this study we use the heavy metal containing textile waste sludge as a precursor for the fabrication of functional electrode material for supercapacitor applications. In this process the organic content within the textile sludge waste is treated at 900 °C and transformed into activated carbon, a vital component of supercapacitors electrodes. Through a series of pyrolysis and activation processes, it is further converted into porous activated carbon (AC) with a wide surface area and appropriate electrochemical properties. To enhance the overall conductivity of the electrode material for supercapacitor applications, the carbon content of the material is increased by loading of reduced graphene oxide (rGO) up to 4 wt%. It resulted in a significant increase in the surface area up to 128.68 m²/g. The effective conversion and relevance of the obtained material for supercapacitor applications is further reinforced by the excellent electrochemical performance of rGO@AC-900 °C which generated a specific capacitance of 362F/g with 4 wt% loading which is higher than the specific capacity achieved with lower rGO loading i.e., 83.2 F/g and 182.5 F/g for AC-900 °C and 2 wt% rGO@AC-900 °C, respectively. The 4 wt% rGO@AC900°C also represented improved stability with up to 82 % charge retention after 5000 charge–discharge cycles. The excellent EDLC behavior of 4 wt% rGO@AC900°C is also evident from the impedance data. The electrode material with 4 wt% rGO loading showed lower value of R_CT i.e., 4.16 Ω as compared to 12.08 Ω with 2 wt% rGO loading. This novel approach offers a sustainable alternative for the handling of hazardous textile waste sludge through conversion into a potential electrode material for environmentally friendly energy storage devices.