Wang, X.X.WangMayrhofer, L.L.MayrhoferHöfer, M.M.HöferEstrade, S.S.EstradeLopez-Conesa, L.L.Lopez-ConesaZhou, H.H.ZhouLin, Y.Y.LinPeiró, F.F.PeiróFan, Z.Z.FanShen, H.H.ShenSchäfer, L.L.SchäferMoseler, M.M.MoselerBräuer, G.G.BräuerWaag, A.A.Waag2022-03-062022-03-062019https://publica.fraunhofer.de/handle/publica/25858410.1002/aenm.201900725Black TiO2 has demonstrated a great potential for a variety of renewable energy technologies. However, its practical application is heavily hindered due to lack of efficient hydrogenation methods and a deeper understanding of hydrogenation mechanisms. Here, a simple and straightforward hot wire annealing (HWA) method is presented to prepare black TiO2 (H-TiO2) nanorods with enhanced photo-electrochemical (PEC) activity by means of atomic hydrogen [H]. Compared to conventional molecular hydrogen approaches, the HWA shows remarkable effectiveness without any detrimental side effects on the device structure, and simultaneously the photocurrent density of H-TiO2 reaches 2.5 mA cm-² (at 1.23 V vs reversible hydrogen electrode (RHE)). Due to the controllable and reproducible [H] flux, the HWA can be developed as a standard hydrogenation method for black TiO2. Meanwhile, the relationships between the wire temperatures, structural, optical, and photo-electrochemical properties are systematically investigated to verify the improved PEC activity. Furthermore, the density functional theory (DFT) study provides a comprehensive insight not only into the highly efficient mechanism of the HWA approach but also its favorably low-energy-barrier hydrogenation pathway. The findings will have a profound impact on the broad energy applications of H-TiO2 and contribute to the fundamental understanding of its hydrogenation.enatomic hydrogenationblack titaniadensity functional theoryelectron energy loss spectroscopyphoto-electrochemical propertytransmission electron microscopy667333journal article