Explicitly controlling electrical current density overpowers the kinetics of the chlorine evolution reaction and increases the hydrogen production during seawater electrolysis

Abstract

The chlorine evolving reaction (CER) subdues the oxygen evolving reaction (OER) during seawater electrolysis, and impedes hydrogen production without generating harmful chlorine byproducts. We describe a new approach to suppressing CER and increasing the hydrogen production rate by highlighting its distinctive features: using electrical current densities Jc > 10 A cm−2 that are much larger than the 1 A cm−2 currents conventionally employed; and using consumable graphite rod-shaped electrodes. Our approach creates a practical means for reaching an electrochemical regime where CER is drastically reduced and hydrogen production is substantially increased. Finite element modeling indicates the rapid reduction in CER is associated with establishing a steep gradient in the electric field between the electrodes. Our study suggests that explicitly elevating Jc to more than 10 A cm−2 creates opportunities for creating hydrogen for use in large-scale and industrial applications by reducing CER to negligible levels – an environmental incentive – while increasing the OER and hydrogen production – an economic incentive.