Comparison of TiO2 and g-C3N4 2D/2D nanocomposites from three synthesis protocols for visible-light induced hydrogen evolution

Knowledge of the interfacial structure of nanocomposite materials is a prerequisite for rational design of nanostructured photocatalysts. Herein, TiO2 and g-C3N4 2D/2D nanocomposites were fabricated from three distinct synthetic protocols (i.e., co-calcination, solvothermal treatment and charge-induced aggregation), showing different degrees of enhancement (1.4-6.1 fold) in the visible-light induced photocatalytic hydrogen evolution reaction compared to the simple physical mixture. We propose that the interfacial TiO- N covalent bonding promotes the charge carrier transfer and separation more effectively than the electrostatic interaction, thus accelerating the photocatalytic H-2 production. Meanwhile, the exposed surface area of TiO2 in the composite needs to be enlarged for deposition of the co-catalyst. This research sheds light on the rational design of hybrid nanocomposites based on earth-abundant elements for photocatalysis.