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

The formation of hexagonal MoO 3 (h- MoO 3) microrods was favoured at lower pH in the hydrothermal synthesis method. Symmetric and Hybrid supercapacitors were fabricated using h-MoO 3 /plastic bottle derived activated carbon (PAC) composite in 1 M Na 2 SO 4 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 3 , helped in faster charge-transfer, hence increasing the efficiency of supercapacitors. Further, the composites of defective PAC (PDAC) together with the h-MoO 3 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 3 provided fast electron transfer towards hydrogen adsorption/desorption hence effectively producing H 2. Image 1 • Maximum operating voltage for supercapacitor study up to 1.6 V with 1 M Na 2 SO 4. • Hybrid supercapacitor with maximum power density of 287 WKg-1. • 79% efficiency retained after 5000 charge-discharge cycles for hybrid combination. • PDAC/h-MoO 3 catalyzed HER at much lower Tafel slope value −98 mVdec−1. • Faster electron transport due to PDAC defects together with hexagonal MoO 3 microrods. [ABSTRACT FROM AUTHOR]