Hierarchical Branched TiO 2 Photo/Photoelectrocatalyst with Directed Charge Transfer for Efficient Hydrogen Production from Seawater.

The directed electron transport channel design in semiconductors, which could promote charge utilization, is attractive but rarely reported. Hierarchical branched titanium dioxide (HB-TiO 2 ), possessing a charge cascade transfer channel, was constructed by assembling titanium-defected TiO 2 nanobranches on oxygen-defected TiO 2 nanobelts. The interfacial Ti/O vacancies have been detected by X-ray photoelectron and electron paramagnetic resonance spectroscopies, and the vacancies act as the "bridge" of photogenerated carrier transport. This structure maintained high photoactivity in H 2 production in different mass fractions of NaCl solutions. The photocurrent density of the HB-TiO 2 photoanode in natural seawater is 3.9, 2.1, and 2.6 times that of oxygen-defected TiO 2 nanobelts, titanium-defected TiO 2 nanobranches, and their mixture, respectively. Besides, the charge transport mechanism from the inner lattice to the TiO 2 surface is proposed.