Hierarchically branched Fe₂O₃@TiO₂ nanorod arrays for photoelectrochemical water splitting: Facile synthesis and enhanced photoelectrochemical performance

Highly photoactive and durable photoanode materials are the key to photoelectrochemical water splitting. In this paper, hierarchically branched Fe₂O₃@TiO₂ nanorod arrays (denoted as Fe₂O₃@TiO₂ BNRs) composed of a long Fe₂O₃ trunk and numerous short TiO₂ nanorod branches were fabricated and used as photoanodes for water splitting. Significant improvement of photoelectrochemical water splitting performance was observed based on Fe₂O₃@TiO₂ BNRs. The photocurrent density of Fe₂O₃@TiO₂ BNRs reaches up to 1.3 mA cm^-2 at 1.23 V versus RHE, which is 10 times higher than that of pristine Fe₂O₃ nanorod arrays under the same conditions. Furthermore, an obvious cathodic shift in the onset potential of photocurrent was observed in the Fe₂O₃@TiO₂ BNRs. More significantly, the Fe₂O₃@TiO₂ BNRs are quite stable even after 3600 s continuous illumination, and the photocurrent density shows almost no decay. Finally, a tentative mechanism was proposed to explain the superior performance of Fe₂O₃@TiO₂ BNRs for PEC water splitting and discussed in detail on the basis of our experimental results.