Conversion of Toluene and Water to Methylcyclohexane and Oxygen using Niobium‐Doped Strontium Titanate Photoelectrodes

Abstract Methylcyclohexane (MCH) is regarded as a promising hydrogen carrier that enables hydrogen to be harnessed as an alternate fuel source, which paves the way to a clean‐energy future. A photoelectrochemical (PEC) system with a Nb:SrTiO 3 photoelectrode for oxygen evolution from an aqueous electrolyte and a Pt/C electrode for toluene (TL) hydrogenation to MCH was investigated under UV irradiation. A Nb:SrTiO 3 single‐crystal electrode and an ionomer/Pt/C membrane‐electrode assembly (MEA) were used as the photoanode and cathode, respectively. A steady‐state current density of 0.12 mA cm −2 was observed for the two‐electrode system without any bias voltage for >2 h, and a Faradaic efficiency of 97 % was obtained for MCH production from TL. This is the first demonstration of the production of MCH from TL and water using only light energy. This means that light energy was converted directly into MCH from TL and water without any electricity. The PEC properties of the devices are discussed.