The study reports electrochemical synthesis, phase evolution and hydrogen generation efficiency of anatase, anatase-rutile and anatase-rutile-brookite (ARB) TiO 2 nanotubes for the first time. The SEM and TEM micrographs confirm the tubular morphology of the samples. The presence of anatase, rutile and brookite phases in a single nanotube is confirmed from high resolution TEM analysis. The water splitting efficiency of the three systems are studied under one sun illumination. It is observed that the anatase-rutile-brookite TiO 2 nanotubes are highly efficient compared to anatase-rutile or anatase TiO 2 nanotubes. The hydrogen generated by ARB composites, after four hours of one sun illumination, is found to be nearly twice that of anatase TiO 2 nanotubes and 1.6 times that of anatase-rutile TiO 2 nanotubes. The results suggest that the ARB in single nanotube having two junction interfaces, highly facilitate inter-particle charge transfer compared to single junction anatase-rutile or bare anatase TiO 2 nanotubes. From the deconvolution of PL spectra and the synchrotron radiation assisted valence band edge analysis, the band diagram for the anatase-rutile-brookite phase is constructed. The charge separation and its transfer pathway for efficient photo-assisted water splitting are delineated. This opens a new route for the simple synthesis and study of tri-phase TiO 2 for efficient photocatalytic water splitting compared to the widely studied two phase TiO 2 .
