Photocatalytic activation of water: A unique way to mimic free hydrogen atoms

The activation of water is a highly desirable but challenging goal for chemists. Recently in Nature, Studer and co-workers reported a photocatalytic phosphine-mediated water-activation strategy that enables efficient radical hydrogenation of plentiful unsaturated compounds. Notably, both hydrogen atoms of H₂O are incorporated through sequential heterolytic and homolytic cleavages of the key intermediate.