Mott-Schottky heterojunction of Se/NiSe2 as bifunctional electrocatalyst for energy efficient hydrogen production via urea assisted seawater electrolysis

Abstract

Seawater electrolysis is considered to be very challenging owing to competitive reaction kinetics in between oxygen evolution reaction and corrosive chlorine evolution reaction mechanism at anode, especially towards higher current density. The present work, proposes a promising and energy efficient strategy by coupling seawater splitting with urea decomposition lowering oxidation potential and thereby avoiding hypochlorite formation even at high current density. The rational design of Mott-Schottky heterojunction of Se/NiSe2 as electrocatalyst is considered to be highly effective in this regard. The developed Se/NiSe2 exhibits extraordinary energy saving for alkaline seawater splitting in presence of urea. The Se/NiSe2/NF || Se/NiSe2/NF electrolyser configuration achieved 10 and 50 mAcm−2 current densities with cell voltage of 1.59 and 1.70 V along with outstanding operational durability over 50 h. The large number of carrier density generates by synergistic self-driven electron transfer from Se to NiSe2 at the heterojunction, unique metallic properties of selenium (Se), and also abundance accessible reactive edges on the porous channel of Ni foam are believed to be the reason behind such enhanced electrocatalytic activities towards urea oxidation reaction and hydrogen evolution reaction offering unique and much energy saving approach for alkaline-urea-seawater electrolysis avoiding hypochlorite formation.