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  Wierzbicka, E.; Szaniawska-Bialas, E.; Schultz, T.; Basilio, A.O.; Siemiaszko, D.; Ray, K.; Koch, N.; Pinna, N.; Polanski, M.: Long-Term Stability of Light-Induced Ti³⁺ Defects in TiO₂ Nanotubes for Amplified Photoelectrochemical Water Splitting. ChemSusChem 17 (2024), p. e202301614/1-10

10.1002/cssc.202301614
Open Access Version

Abstract:
This study shows that the simple approach of keeping anodic TiO2 nanotubes at 70°C in ethanol for 1 h results in improved photoelectrochemical water splitting activity due to initiation of crystallization in the material amplified by the light-induced formation of a Ti3+􀀀 Vo states under UV 365 nm illumination. For the first time, the light-induced Ti3+􀀀 Vo states are generated when oxygen is present in the reaction solution and are stable when in contact with air (oxygen) for a long time (two months). We confirmed here that the amorphous or nearly amorphous structure of titania supports the survival of Ti3+ species in contact with oxygen. It is also shown that the ethanol treatment substantially improves the morphology of the titania nanotube arrays, specifically, less surface cracking and surface purification from C- and F-based contamination from the electrolyte used for anodizing.