Enhanced Photoelectrochemical Performance by Interface Engineering in Ternary g-C3N4/TiO2/PbTiO3 Films

Polycrystalline ferroelectric PbTiO3 (PTO) films deposited on transparent fluorine-doped tin oxide (FTO) glass have been proved to be a photocathode for photoelectrochemical (PEC) water splitting. However, the hitherto reported PEC performances remain inferior to meet the requirements for practical applications. Herein, it is reported that a compact TiO2 (TO) buffer layer, inserted between PTO and g-C3N4 (CN), improves significantly its PEC performance. The optimal CN/TO/PTO film shows a photocathodic current density of -68.5 mu A cm(-2) at 0 V versus Ag/AgCl electrode under 100 mW cm(-2) Xe-lamp illumination, which is 4.5 and 2 times higher than that of pristine PTO and CN/PTO films. The performance improvement can be attributed to the following reasons: one is the improved light harvesting ability owing to TO and CN, and the other is that TO functions as a buffer layer to build a type II and a Z-scheme interfaces between PTO, TO, and CN to promote charge carrier transfer and separation. Last but not the least, the ternary photoelectrode also shows tunable PEC performance by ferroelectric polarization switching.