Flame Reduced TiO2 Nanorod Arrays with Ag Nanoparticle Decoration for Efficient Solar Water Splitting

Low photogenerated charge density and fast surface charge recombination of TiO2 are two critical factors hampering its solar-to-hydrogen conversion for photoelectrochemical water splitting. Herein, we demonstrate an efficient and facile flame reduction method to produce rich oxygen vacancies in single-crystal rutile TiO2 nanorod arrays without destroying the catalyst and conductive substrate at ambient conditions. The oxygen vacancies improve the conductivity of TiO2 and act as the role that intermediate electron donor increases the charge density. We further construct a Schottky junction by depositing Ag nanoparticles on the flame reduced TiO2 to enhance surface charge separation efficiency. The optimal TiO2 photoelectrodes exhibit an astonishing surface charge separation efficiency of 91% as well as photocurrent density as high as 1.52 mA cm–2 (at 1.23 V, vs reversible hydrogen electrode), which is ∼7.2 times that of the pristine rutile TiO2 (0.21 mA cm–2). This work demonstrates that the facile flame reduction method combined with Schottky junction construction exhibits significant application prospects for the enhanced solar conversion efficiency of metal oxide photoelectrodes.