Enhanced Performance of Photoelectrochemical Water Splitting with ITO@α-Fe2O3 Core-Shell Nanowire Array as Photoanode

Hematite (alpha-Fe2O3) is one of the most promising candidates for photoelectrodes in photoelectrochemical water splitting system. However, the low visible light absorption coefficient and short hole diffusion length of pure alpha-Fe2O3 limits the performance of alpha-Fe2O3 photoelectrodes in water splitting. Herein, to overcome these drawbacks, single-crystalline tin-doped indium oxide (ITO) nanowire core and alpha-Fe2O3 nanocrystal shell (ITO@alpha-Fe2O3) electrodes were fabricated by covering the chemical vapor deposited ITO nanowire array with compact thin alpha-Fe2O3 nanocrystal film using chemical bath deposition (CBD) method. The J-V curves and IPCE of ITO@alpha-Fe2O3 core shell nanowire array electrode showed nearly twice as high performance as those of the alpha-Fe2O3 on planar Pt-coated silicon wafers (Pt/Si) and on planar ITO substrates, which was considered to be attributed to more efficient hole collection and more loading of alpha-Fe2O3 nanocrystals in the core shell structure than planar structure. Electrochemical impedance spectra (EIS) characterization demonstrated a low interface resistance between alpha-Fe2O3 and ITO nano wire arrays, which benefits from the well contact between the core and shell. The stability test indicated that the prepared ITO@alpha-Fe2O3 core shell nanowire array electrode was stable under AM1.5 illumination during the test period of 40 000 s.