Diesel Soot as a Supercapacitor Electrode Material

Abstract

Diesel soot (DS) collected directly from the exhaust tailpipe of the diesel-powered vehicle was explored for its performance as an electrochemical supercapacitor electrode material. X-ray diffraction and Raman spectroscopy evidenced the existence of graphite carbon form in DS along with low amount of defects in the form of disordered graphite, amorphous carbon, ionic, and polyene impurities. The carbon (C, ∼94 at.%) and oxygen (O, ∼5 at.%) elements were identified using the X-ray photoelectron spectroscopy technique on the DS surface. The morphology of DS powder consisted of nanoparticles with nearly spherical-shaped morphology as observed under the scanning electron microscope. Further, the transmission electron microscope showed the chain type interconnectivity of DS nanoparticles. The average surface area, average pore radius, and total pore volume of DS were measured to be 88 m2 g−1, 1.62 nm, and 0.17 cc g−1, respectively. Cyclic voltammetry and galvanostatic charge-discharge studies were performed to explore the electrochemical behavior of DS slurry-coated electrode. The supercapacitor behavior of DS was studied using various aqueous and organic electrolytes. Higher values of specific capacitance (Csp) were achieved for DS in the case of aqueous electrolytes in comparison to organic electrolytes. The observed highest specific capacitance (Csp) value was 36.77 F g−1 for DS at the current density value of 0.25 A g−1 using 0.5 M H2SO4 electrolyte. DS retains nearly 78.10% of its initial capacitance even after the execution of 5000 cycles, clearly indicating the excellent durability and stability of the material. Thus, DS could be a promising supercapacitor electrode material.