Graphene–carbon nanotube composite as an effective conducting scaffold to enhance the photoelectrochemical water oxidation activity of a hematite film

Abstract

The iron oxide photoanode was modified with a graphene–carbon nanotube (CNT) composite conducting scaffold for efficient charge transfer from Fe₂O₃ particles to transparent conducting oxide substrate in photoelectrochemical water splitting cells. The Fe₂O₃–composite photoanode showed a photocurrent increase of 530% compared with to the bare Fe₂O₃ photoanode at 1.23 V vs. RHE, while the increase was only 200 and 240% for Fe₂O₃–CNT and Fe₂O₃–graphene photoanodes, respectively. This remarkable performance enhancement by the composite scaffold was attributed to synergistic effects induced by the formation of a 3D-like architecture from 1D CNT and 2D graphene. They become a spacer for each other forming a more open and highly exposed structure, in which both 2D graphene and 1D CNT can exist in the forms with much less self-agglomeration, thus not only enlarging the contact area between the conducting scaffold and Fe₂O₃ particles but also recovering in part the intrinsic conducting ability of graphene and CNT.