Self-organized TiO_(2)Nanotube Arrays with Controllable Geometric Parameters for Highly Efficient PEC Water Splitting

In this report,a series of self-organized TiO_(2)nanotube arrays were prepared by anodization of titanium foil in mixed electrolytes composed of water,ethylene glycol,and NH_(4)F.Their photoelectrochemical(PEC)performance as a photoanode was characterized by the PEC water-splitting hydrogen(H_(2))generation reaction.The internal relationship between the TiO_(2)nanotube arrays(TNTAs)morphology and their PECperformance was thoroughly investigated.Our results show that when the etching time is 10 hours,the length of the as-prepared TNTAs is about 20.78μm and the measured photocurrent density is around 1.25 m A·cm^(-2)with applied bias voltage 0.6 V(vs.Ag/Ag Cl)under simulated sunlight irradiation,which is 976 times higher than that of the TiO_(2)substrate without nanotubes architecture(0.00128 m A×cm^(-2)).More interestingly,the results of the IPCEmeasurement show that the band-gap of the as-prepared TNTAs is reduced from 3.20 to 2.83 eV.The corresponding optical response limit is also extended from 400 nm to TiO_(2)nanotube arrays is 510 nm,which indicates that the increasement of the TNTAs PEC performance benefits from the great improvement of its utilization of both the UVand visible light irradiation.