High power density and improved H2 evolution reaction on MoO3/Activated carbon composite

Abstract

The formation of hexagonal MoO<inf>3</inf> (h- MoO<inf>3</inf>) microrods was favoured at lower pH in the hydrothermal synthesis method. Symmetric and Hybrid supercapacitors were fabricated using h-MoO<inf>3</inf>/plastic bottle derived activated carbon (PAC) composite in 1 M Na<inf>2</inf>SO<inf>4</inf> aqueous electrolyte. The operating voltage for the aqueous electrolyte was maximized to 1.6 V with this combination. The wide operating voltage led to a maximum specific capacitance of 211 Fg-1, power density of 287 W kg?1 and 79% efficiency even at 5000 charge-discharge cycles for the hybrid supercapacitor combination. The combined effect of PAC micropores along with the 1-D rod-shaped h-MoO<inf>3</inf>, helped in faster charge-transfer, hence increasing the efficiency of supercapacitors. Further, the composites of defective PAC (PDAC) together with the h-MoO<inf>3</inf> when tested for hydrogen evolution reactions (HER), provided lesser onset potential and Tafel slope values of ?0.23 mV and ?93 mVdec?1. There was a change in the structural environment of carbon due to the heteroatom doping and dedoping producing defects in PAC, termed as PDAC. These defects together with the hexagonal microrods of MoO<inf>3</inf> provided fast electron transfer towards hydrogen adsorption/desorption hence effectively producing H<inf>2</inf>. © 2019 Hydrogen Energy Publications LLC