SnFe₂O₄/ZnIn₂S₄/PVDF piezophotocatalyst with improved photocatalytic hydrogen production by synergetic effects of heterojunction and piezoelectricity

The polarized electric field inside piezoelectric materials has been proven to be a promising technique to boost photogenerated charge separation. Herein, a novel flexible SnFe2O4/ZnIn2S4/polyvinylidene fluoride ((CH2CF2)n, PVDF) (P–SZ) film piezophotocatalyst was successfully synthesized by combining PVDF, an organic piezoelectric material, with a 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 that of pristine ZIS. Furthermore, 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 approximate factor of 2.0. Based on 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 multi-path collection and utilization of natural solar and vibrational energy to enhance photoactivity.</p

Band-Gap Tuning of Organic–Inorganic Hybrid Palladium Perovskite Materials for a Near-Infrared Optoelectronics Response

Organic–inorganic hybrid material is a recent hot topic in the scientific community. The best band gap for the entire solar absorption spectrum is about 1.1 eV. However, the lead perovskite band gap is about 1.5 eV. Therefore, developing organic–inorganic hybrid material toward the broader light harvesting of the solar spectrum is extremely urgent. In this study, we prepare three kinds of organic–inorganic hybrid palladium perovskite materials, including (CH3NH3)2PdCl4, (CH3NH3)2PdCl4–xBrx, and CH3NH3PdI3, for an optoelectronic response. The absorption cut offs of (CH3NH3)2PdCl4, (CH3NH3)2PdCl4–xBrx, and CH3NH3PdI3 are approximately 600, 700, and 1000 nm, respectively. The band gaps of (CH3NH3)2PdCl4, (CH3NH3)2PdCl4–xBrx, and CH3NH3PdI3 are determined to be approximately 2.15, 1.87, and 1.25 eV, respectively. To the best of our knowledge, this is the first study that discusses adsorption properties and photoelectric behavior of organic–inorganic hybrid palladium perovskite materials. Interestingly, the photoelectric response of the devices based on CH3NH3PdI3 reaches 950 nm. The results will attract attention in the fields of optical recorders, optical memory, security, light capture, and light treatment