Mnemonic Rutile–Rutile Interfaces Triggering Spontaneous Dissociation of Water

摘要

Water interaction with mineral surfaces is a complex living system decisive forany photocatalytic process. Resolving the atomistic structure ofmineral–water interfaces is thus crucial for understanding these processes.Fibrous rutile TiO_2, grown hydrothermally on twinned rutile seeds underacidic conditions, is studied in terms of interface translation, atomic structure,and surface chemistry in the presence of water, by means of advancedmicroscopy and spectroscopy methods combined with structure modelingand density functional theory calculations. It is shown that fibers whilestaying in stable separation during their growth, adopt a specialcrystallographic registry that is controlled by repulsion forces between fullyhydroxylated and protonated (110) surfaces. During relaxation, a turbulentproton transfer and cracking of O-H bonds is observed, generating a strongacidic character via proton jump from bridge -OH~b to terminal -OH~t groups,and spontaneous dissociation of interfacial water via a transient protonationof the -OH~t groups. It is shown, that this specific interface structure can beimplemented to induce acidic response in an initially neutral medium whenre-immersed. This is thought to be the first demonstration ofquantum-confined mineral–water interface, capable of memorizing its pastand conveying its structurally encoded properties into a new environment.