Increasing the Efficiency of Water Splitting through Spin Polarization Using Cobalt Oxide Thin Film Catalysts
Supriya Ghosh, Brian P. Bloom, Yiyang Lu, Daniel N. Lamont, David H. Waldeck
Abstract
This work explores the use of chiral cobalt oxide thin film electrocatalysts for the oxygen evolution reaction and examines how their spin polarization properties might be used to control electrochemically generated intermediates at different pH values. These studies demonstrate that chiral cobalt oxide electrocatalysts reduce the reaction overpotential by 65 mV at 10 mA/cm2, increase the oxygen yield by 1.4-fold at a fixed current density at pH 10, and decrease the production of hydrogen peroxide by 4.0-fold as compared to that of the corresponding meso-CoOx analogues. Additional studies in which the electrocatalyst is modified to make it paramagnetic exhibit a similar enhancement with an applied external magnetic field. The findings from these studies are described using a proposed mechanistic model, which unifies the favorable effects of chirality and magnetization. The results are attributed to the advantage of spin-polarized intermediates in facilitating the oxygen evolution reaction.