Microwave synthesis of self-supported Bi/NF anodes with ultra-high capacity for supercapacitors and hydrogen evolution reaction

Abstract

Bi nanoflakes on Ni foam (NF) for supercapacitors (SCs) are prepared by simple one-step microwave irradiation without further calcination. XRD and XPS results reveal the successful synthesis of Bi crystal. SEM and EDS results uncover the growth of Bi and the constituent elements of the complexes. The Bi anode on NF (Bi/NF) not only enables an ultra-large specific capacity of 4651 F g−1 (1 A g−1) and a capacity maintenance rate of 75% (after 1000 cycles), but it also exhibits outstanding catalytic hydrogen precipitation reaction, reaching an overpotential of −136 mV versus the reversible hydrogen electrode at −10 mA cm−2 and Tafel slope of 114.4 mV dec−1. The Bi anode is gathered into the asymmetric SC, which demonstrates an ultra-high energy density of 125 Wh kg−1 (power density of 640 W kg−1) in an alkaline electrolyte.