[17p-D419-1~15] 6.4 Thin films and New materials

▲ [17p-D419-15] Multiferroic ε-Fe₂O₃ Thin Films for Highly Efficient Visible Light Photoelectrochemical Water Splitting

〇Xinjue Wang¹, Haining Li¹, Hiroyasu Yamahara¹, Hitoshi Tabata¹, Munetoshi Seki¹ (1.Tokyo Univ.)

Keywords:Multiferroic thin film, photoelectrochemical water splitting

Herein, single-phase ε-Fe₂O₃ thin film was grown on SrTiO₃ (111) substrate through a pulsed laser deposition technique, with a growth temperature and an oxygen pressure of 700°C and 11 Pa, respectively. The X-ray diffraction 2θ/ω pattern for the ε-Fe₂O₃ film is shown in Fig.1. The ε-Fe₂O₃ thin film was highly oriented along the (004) direction. The epitaxial growth was confirmed using reciprocal space mapping of the (2010) reflection of the ε-Fe₂O₃ film and the (313) reflection of SrTiO₃ substrate. The in-plane epitaxial relationship ε-Fe₂O₃ (200)//SrTiO₃ (1–21) was also revealed. The three-electrode j-V measurement was conducted under visible light and UV light illumination condition, as shown in Fig. 2. We applied Pt as a counter electrode, 3M NaCl saturated Ag/AgCl as a reference electrode, and the photoelectrode samples as working electrode. The bandgap of ε-Fe₂O₃ was evaluated to be 2.1 eV using the Tauc plot. It could be observed that ε-Fe₂O₃ can produce photogenerated charge carriers without an external bias (0 V). The incident photon-to-current efficiency (IPCE) can reach 76.4% at the wavelength of 390 nm. This research might contribute to the water splitting application by providing a room-temperature multiferroic candidate.