Photoelectrochemical Production of Hydrogen Peroxide with TiO2 and 1,5-Di(thien-2-yl)-9,10-anthraquinone via a Selective Two-Electron Oxygen Reduction Reaction in the Two-Compartment Cell

Abstract

The industrial process of hydrogen peroxide (H2O2) synthesis proceeds through the hydrogenation of anthraquinone followed by successive oxidation in an organic solvent. This process is a multistep synthesis that is far away from green synthesis. An alternative photoelectrochemical (PEC) H2O2 production method requires only sunlight and water. Herein, we established the direct production of H2O2 by using a two-compartment PEC cell composed of TiO2 nanorods hydrothermally grown on fluorine-doped tin oxide as a photoanode for water oxidation and 1,5-di(thien-2-yl)-9,10-anthraquinone (AQTh) anchored carbon cloth as a cathode for the selective two-electron (2e–) reduction of oxygen. This photoanode and cathode are positioned in an anodic compartment and a cathodic compartment of a two-compartment cell, respectively. The Nafion membrane (N-117) separates these two compartments. This PEC cell continuously produces H2O2 at −0.1 VRHE applied voltage, which reaches 60 μM after 3 h. The density functional theory study is carried out to better understand the H2O2 production mechanism and the role of thiophene substituents on anthraquinone.