  Black TiO2 with/without noble metal has been proposed for visible
photocatalyst, still leaving poor catalyst efficiency. Alternatively,
phase-mixed TiO2 such as anatase and rutile has been commonly used for visible
catalysts with the inevitable inclusion of noble metal. Here, we perform a
noble metal-free visible photocatalyst blue TiO2 with type-II band-aligned
ordered anatase/disordered rutile structure, via phase-selective reduction with
alkali metals. The changed band alignment in this heterostructure was
identified by absorption and ultraviolet photoemission spectroscopy, which was
further confirmed by transient charge separation. The band alignment of type-I
and type-II was clearly restructured by converting from ordered to disordered
phase with a prolonged reduction period and as followed light absorbance
enhancement also observed. Initiated type-I in a pristine sample, the type-II
was organized from disordered rutile phase in 3-day Li-reduction. The type-II
disordered rutile TiO2 heterostructure exhibits a remarkable photocatalytic
performance by 55 times higher than conventional P25 TiO2 in solar-light driven
hydrogen evolution reaction owing to an efficient electron and hole separation
of type-II heterojunction. Furthermore, this restructured heterojunction
type-II TiO2 demanded 10 times less Pt amount as a co-catalyst for the
comparable photocatalytic performance, compared to Pt decorated type-I pristine
anatase/rutile phase-mixed TiO2.
