Atomic Layer Deposition Grown Titania Phases (TiO₂, TiO, Ti₂O) and its Influence on Water Splitting Electrocatalysis

Abstract The systematic engineering of atoms and the precise tuning of their arrangement can unlock a range of hidden yet remarkable properties of materials. In this study, different phases of titanium oxide, including TiO 2 , TiO, and Ti 2 O, are developed using the Atomic Layer Deposition (ALD) technique. Notably, a novel Ti 2 O electride with a pbcn space group is identified, and variations in stoichiometries, such as Ti 1.80 O, Ti 2.05 O, and Ti 2.30 O, are observed through Rietveld analysis of the corresponding X‐ray Diffraction (XRD) data. High‐resolution transmission electron microscopy (HRTEM) imaging further revealed line defects such as stacking faults and edge dislocations in Ti 2 O. The interplay of stoichiometric defects in Ti 2 O electrides leads to tunable electrocatalytic behavior, enabling transitions from oxygen evolution to hydrogen evolution reactions. Importantly, using Density functional theory (DFT), Paterson analysis, and Fourier electron density mapping, the exceptional metallic properties of Ti 2 O are rationalized as arising from its unique spatial electron density distribution. Overall, this work underscores the significance of atomic‐level structure engineering and opens the door to a new class of titanium oxide catalysts for electrochemical water splitting.