Graphitic carbon nitride (g-C3 N4) with the merits of high visible light absorption,proper electronic band structure with high conduction band edge and variable modulation,is viewed as a promising photocatalyst for practical use.To alleviate its high recombination rate of photo-excited charge carriers and maximize the photocatalytic performances,it is paramount to design highly effective transfer channels for photo-excited charge carriers.Ferroelectric materials can have the charge carriers transport in opposite directions owing to the internal spontaneous polarization,which may be suitable for constructing the heterostructure with g-C3N4 for efficient charge separation.Inspired by this concept,herein ferroelec tric PbTiO3,which can be the visible-light absorber,is coupled with g-C3N4 to construct PbTiO3/g-C3N4 heterostructure with close contact via Pb-N bond by the facile post thermal treatment.The optimized PbTiO3/g-C3N4 heterostructure exhibited excellent photocatalytic and photoelectrochemical activities under visible light irradiation.Moreover,the simultaneous application of ultrasound-induced mechanical waves can further improve its photocatalytic activities through reinforcing the built-in piezoelectric field.This work proposes a widely applicable strategy for the fabrication of high-performance ferroelectric based photocatalysts and also provides some new ideas for developing the understanding of ferroelectric photocatalysis.