Z-scheme TiO2/g-C3N4 composites with improved solar-driven photocatalytic performance deriving from remarkably efficient separation of photo-generated charge pairs

•There exists a strong interaction between TiO2 and g-C3N4.•The photo-induced charge separation rate has been greatly enhanced.•The photocatalytic activity has been remarkably promoted.•The composites follow a typical Z charge separation and migration mechanism.