Laser-assisted synthesis of Z-scheme TiO2/rGO/g-C3N4 nanocomposites for highly enhanced photocatalytic hydrogen evolution

Constructing nanocomposite structures with favorable charge transfer routes is an effective way to obtain highly efficient photocatalysts. Herein, fabrication of indirect and noble metal-free Z-scheme photocatalytic architecture is demonstrated using pulsed laser ablation in liquids (PLAL) technique for the first time. The as-prepared ternary photocatalyst (denoted as TiO2/rGO/g-C3N4) comprises titanium dioxide (TiO2) nanotubes, reduced graphene oxide (rGO) nanosheets, and graphitic carbon nitride (g-C3N4) nanosheets. The photocatalytic activity of the as-synthesized composite is evaluated by monitoring water splitting. Various analytical techniques were employed to investigate the compositional, morphological, structural, and optical properties of the photocatalysts. The system of TiO2/rGO/g-C3N4 with the weight ratio of TiO2 to g-C3N4 of 2:4 and 1% rGO exhibited the highest hydrogen production rate of 32 +/- 1 mmol g(-1)h(-1), which is about 93, 3.8 and 2.6 times higher than those of pure g-C3N4, TiO2, and TiO2/rGO, respectively. This enhanced performance can be ascribed to the strong interfacial bonding (TiO2/rGO/g-C3N4), extended visible light absorption capacity due to higher photo-responsiveness of rGO and g-C3N4, the synergetic effect between TiO2 and g-C3N4 and direct contact between TiO2 and rGO which facilitated efficient separation and transfer of photogenerated charges. This study opens opportunities for the fabrications of different Z-scheme systems for various applications.