Hydroxyl Radical Suppression during Photoelectrocatalytic Water Oxidation on WO₃|FeOOH

Abstract

Depositing the earth-abundant water oxidation electrocatalyst FeOOH onto WO3 has been shown to increase the Faradaic efficiency of the tandem WO3|FeOOH photoanode to near 100% for the photoelectrocatalytic oxidation of water to oxygen. Here we begin to explore how this gain in Faradaic efficiency is imparted through hydroxyl radical trap and Tafel experiments. It was found that increasing the FeOOH deposition time of the WO3|FeOOH caused a decrease in the quantity of hydroxyl radical trapped during photoelectrocatalytic water oxidation. These results, along with the disparate Tafel slopes of bare WO3 and WO3|FeOOH, suggest a change in the water oxidation mechanism between the two materials.