SnFe 2O 4/ZnIn 2S 4/PVDF piezophotocatalyst with improved photocatalytic hydrogen production by synergetic effects of heterojunction and piezoelectricity

The polarized electric field inside piezoelectric materials has been proved to be promising technique to boost the photogenerated charge separation. Herein, a novel flexible SnFe₂O₄/ZnIn₂S₄/PVDF (P-SZ) film piezophotocatalyst was successfully synthesized by combining poly vinylidene fluoride (PVDF), an organic piezoelectric material, with SnFe₂O₄/ZnIn₂S₄ (SFO/ZIS) type II heterojunction photocatalyst. The hydrogen evolution rate of SFO/ZIS heterojunction with a SFO content of 5% is about 846.79 μmol h^-1 g^-1, which is 3.6 times higher than that of pristine ZIS. Further, after being combined with PVDF, the optimum hydrogen evolution rate of P-SZ is about 1652.7 μmol h^-1 g^-1 in the presence of ultrasound, which exceeds that of 5%SFO/ZIS by an approximately factor of 2.0. Based on the experimental results, the mechanism of the improved photocatalytic performance of P-SZ was proposed on the basis of the piezoelectric field in PVDF and the formed heterojunction between SFO and ZIS, which effectively boosted the separation of photoinduced charges. This work provides an efficient strategy for the multi-path collection and utilization of natural solar and vibrational energy to enhance the photoactivity.