Achieving Highly Efficient Photoelectrochemical Water Oxidation with a TiCl4 Treated 3D Antimony‐Doped SnO2 Macropore/Branched α‐Fe2O3 Nanorod Heterojunction Photoanode

Utilizing photoelectrochemical (PEC) cells to directly collecting solar energy into chemical fuels (e.g., H2 via water splitting) is a promising way to tackle the energy challenge. α-Fe2O3 has emerged as a desirable photoanode material in a PEC cell due to its wide spectrum absorption range, chemical stability, and earth abundant component. However, the short excited state lifetime, poor minority charge carrier mobility, and long light penetration depth hamper its application. Recently, the elegantly designed hierarchical macroporous composite nanomaterial has emerged as a strong candidate for photoelectrical applications. Here, a novel 3D antimony-doped SnO2 (ATO) macroporous structure is demonstrated as a transparent conducting scaffold to load 1D hematite nanorod to form a composite material for efficient PEC water splitting. An enormous enhancement in PEC performance is found in the 3D electrode compared to the controlled planar one, due to the outstanding light harvesting and charge transport. A facile and simple TiCl4 treatment further introduces the Ti doping into the hematite while simultaneously forming a passivation layer to eliminate adverse reactions. The results indicate that the structural design and nanoengineering are an effective strategy to boost the PEC performance in order to bring more potential devices into practical use.