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

Yang‐Fan Xu,Cheng‐Yong Su,Hua‐Shang Rao,Ying Lin,Bai‐Xue Chen,Hong‐Yan Chen,Dai‐Bin Kuang

doi:10.1002/advs.201500049

Abstract

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.

Highlights

Diffusion length (
For the first time we demonstrate a novel 3D antimony-doped SnO2 (ATO) macroporous structure as transparent conducting scaffolds incorporating with 1D hematite nanorod as composite heterostructure photocatalyst for efficient PEC water splitting
The macroporous ATO structure was prepared by drop casting the polystyrene (PS)/ATO suspension solution which was synthesized by modified template-assisted method[9b,13] onto FTO glass and followed an annealing process to remove the PS template

Summary

Results and Discussions

The high resolution transmission electron microscope (HRTEM) image (Figure S2d, Supporting Information) further reveals the ATO hollow sphere is composed of 5 nm nanoparticles and the spacings between the adjacent lattice fringes are 0.3328 and 0.2632 nm, corresponding to (110) and (101) planes of the SnO2, while both of which evince a shrink compared to the standard data. FE-SEM images (Figure 1a,b) display the top and cross-sectional views of the 10% Sb doping macroporous antimony-doped SnO2/ branched α-Fe2O3 nanorod (10%-mpATO/BHNR) film. The dense hematite nanorods epitaxially growing on the surface of ATO macropores to form a 3D architecture, which might be ascribed to the low interfacial lattice mismatch between SnO2 and FeOOH.[14] TEM image (Figure 1c) further shows the hematite nanorod was approximately 120 nm in length and 20 nm in diameter. The clear lattice fringes with spacing of 0.2470 nm in HRTEM images (Figure 1d) agrees well with the (110) plane of the hematite

Photoelectrochemical Water-Splitting Performance

The Influence of TiCl4 Post Treatment

Experimental Section

Conclusion