Waste engine oil derived porous carbon/ZnS Nanocomposite as Bi-functional electrocatalyst for supercapacitor and oxygen reduction

Herein, we report the effective conversion of waste automobile engine oil into porous activated carbon/ZnS nanocomposite. Initially, the waste engine oil was thermally decomposed under an argon atmosphere at 700 °C and followed by acid treatment with a 10% piranha solution to form activated carbon/ZnS (ACZS) nanocomposites. The ACZS was used as electrode active material for symmetric supercapacitor and electrocatalyst for oxygen reduction reaction (ORR) studies. It is interesting to note that, the ACZS electrode performed well for supercapacitor delivered a high specific capacitance of 241 F/g at 1 A/g current density. The symmetric supercapacitor cell fabricated using ACZS electrodes delivered a high specific energy and specific power of 13.8 Wh/kg and 4500 W/kg with an exceptional electrochemical stability of 95% for 10,000 cycles, respectively. The electrochemical RRDE studies shows higher ORR current density of ACZS electro-catalyst (4.46 mA/cm²) than that for the HiSPEC Pt/C catalyst (3.91 mA/cm²).