Waste PET plastic derived ZnO@NMC nanocomposite via MOF-5 construction for hydrogen and oxygen evolution reactions

Abstract

Waste PET plastic is the main solid waste to deteriorate the environment. Herein, we have utilized waste PET plastic to synthesize nitrogen doped mesoporous carbon functionalized zinc oxide (ZnO@NMC) nanocomposite through MOF-5 construction by low temperature solvothermal method for the first time. As per current energy needs, sustainable hydrogen production through water splitting is the modern appealing solution across the globe. The existence of carbon and nitrogen in ZnO@NMC nanocomposite were confirmed by several analytical techniques i.e. XRD, FTIR, CHN, and XPS. High specific surface area of (939 m2/g) and meso-porosity (pore radius ~25 Å) may offer large number of active sites and easy charge relocation for hydrogen and oxygen evolution reactions via electro-catalysis. The prepared ZnO@NMC nanocomposite exhibits enhanced electro-catalytic activity for HER and OER in 0.5 M KOH solution. Tafel slope and over-potential (ƞ10) of ZnO@NMC nanocomposite were found to be ~108 mV/dec and 0.39 mV, correspondingly, for HER in 0.5 M KOH. ZnO@NMC nanocomposite also shows efficient OER electro-activity with Tafel slope and over-potential (ƞ10) of ~318 mV/dec and ~0.57 V respectively. ZnO@NMC nanocomposite shows better electro-catalytic performance compared to the reported pure ZnO nanostructures. Moreover, the constancy test was also checked through chrono-amperometry (CA) at fixed potential.