Alternative Oxidation Reactions for Solar-Driven Fuel Production

For nearly half a century, water oxidation has been extensively investigated as the electron source for solar powered H₂ fuel production from water. However, despite a thermodynamic potential of only 1.23 V required at standard conditions, driving the oxygen evolution reaction (OER) typically requires 1.5 - 1.8 V resulting in a significant loss. Over the last decade, numerous researchers have begun to re-explore the idea of replacing water oxidation with more kinetically facile oxidation reactions in photoelectrochemical and photocatalytic solar H₂ production systems. Alternate photooxidation reactions can be employed as a means of chemical valorization, in addition to providing electrons for H₂ production from water while reducing the losses associated with the OER. In a new article from LIMNO, Dr. Lhermitte and Prof. Sivula discuss other possible oxidation reactions, and in particular recent progress in the investigation of organic based photo-oxidation reactions is highlighted. The focus is on oxidation reactions that have potential applications as a form of chemical valorization, and that can take place in aqueous solutions to allow concurrent H₂ production via water reduction at a (photo)cathode. A critical assessment and an outlook towards the prospective large scale implementation of this technology is finally considered.