α-Fe2O3 nanorods embedded with two-dimensional {0 0 1} facets exposed TiO2 flakes derived from Ti3C2TX MXene for enhanced photoelectrochemical water oxidation

Abstract

The Sn-doped α-Fe2O3 nanorods were embedded with {0 0 1} facets exposed TiO2 flakes by a facile hydrothermal synthesis and post-calcination treatment (denoted as E-Sn-Fe2O3/TiO2). The {0 0 1} facets exposed TiO2 flakes were derived from the delaminated Ti3C2TX MXene (D-Ti3C2TX) without adding extra HF or F ions during hydrothermal synthesis because the surface of D-Ti3C2TX was natively terminated by –F functional groups. The Sn-doped hematite/surface-covered TiO2 (denoted as S-Sn-Fe2O3/TiO2) and Sn-doped hematite (denoted as Sn-Fe2O3) were also fabricated for comparison. Under simulated sunlight, the E-Sn-Fe2O3/TiO2 yielded a photocurrent density of 0.85 mA cm−2 at 1.23 V (vs. RHE) compared with 0.72 mA cm−2 and 0.42 mA cm−2 for S-Sn-Fe2O3/TiO2 and Sn-Fe2O3, respectively. The E-Sn-Fe2O3/TiO2 achieved an IPCE value of 18.6% at 380 nm (15.8% for S-Sn-Fe2O3/TiO2 and 10.4% for Sn-Fe2O3) and exhibited enhanced IPCE values at all measured wavelengths compared with the other two photoanodes. The unique architecture of embedded TiO2 can improve the interfacial contact between the α-Fe2O3 and TiO2 as well as the light harvesting of the α-Fe2O3 compared with the surface-covered TiO2, which contributes to the better charge-transport ability and enhanced PEC performance. The exposed {0 0 1} facets of TiO2 in the E-Sn-Fe2O3/TiO2 photoanode may also facilitate the charge transfer and improve the PEC performance.