Bimetallic chalcogenide nanocrystallites as efficient electrocatalyst for overall water splitting

Abstract

To design and develop an efficient cost effective, easily available and highly stable bi-functional catalyst with enhanced rate of hydrogen and oxygen evolution at anode and cathode, respectively, is a challenging task in production of green and renewable energy. As a replacement of very costly Pt/C and IrO2 as cathode and anode materials, respectively, used in water splitting, we have synthesized and characterized two bimetallic nanocrystallites (FeNiSe2 and FeNiSSe) and studied their bi-functional electrocatalytic activity in acidic and alkaline medium for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Out of these two electrocatalysts, FeNiSSe nanotube is more efficient bi-functional electrocatalyst as compare to FeNiSe2. The electrocatalyst FeNiSSe nanotube required overpotential of 213 mV for oxygen evolution reaction and 91.2 mV for hydrogen evolution reaction to achieve current density 10 mA/cm2. Besides OER and HER, FeNiSSe nanotube also acts as good bi-functional electrocatalyst for overall water splitting in 1.0 M KOH with small cell voltage 1.56, 1.64 and 1.78 V to reach current density 10, 20 and 50 mA/cm2, respectively. The remarkable electrocatalytic activity of the FeNiSSe nanotube as compare to FeNiSe2 is due to its lower overpotential, lower Tafel slope value and well distinct nanotube shaped with larger BET surface area, ECSA, ESA, active sites and smaller charge transfer resistance.