Design and synthesis of an S-scheme TiO2 homojunction with an adjusted, well-defined phase for directional carrier transfer in solar water splitting

Abstract

The rational design and controlled synthesis of nanoarchitectures is an important strategy for understanding structure–activity relationships. Herein, a novel tufted nanoneedle embedded localized microsphere (TELM) nanoarchitecture is proposed, that is, tufted rutile TiO₂ nanoneedles are embedded on the localized surface of anatase TiO₂ microspheres (TiO₂-TELM). The decay lifetime of photogenerated charge carriers (PCCs) in TiO₂-TELM could be prolonged by 38.8% and 34.8% relative to that in pure rutile and anatase TiO₂, respectively. Particularly, TiO₂-TELM with a 1 wt% Pd loading could deliver an ultrahigh H₂ production rate value of 816.0 μmol g⁻¹ h⁻¹ in pure water. Moreover, photogenerated e⁻ and h⁺ in TiO₂-TELM migrate toward the rutile and anatase phases of TiO₂, respectively. This study provides an effective nanoarchitecture synthesis strategy for solving the paradoxical process of increasing the size of dispersed phase nanoparticles and maintaining the substrate surface area.