Parallel multi-stacked photoanodes of Sb-doped p-n homojunction hematite with near-theoretical solar conversion efficiency.

Xu, Chenyang; Wang, Hongxin; Guo, Hongying; Liang, Ke; Zhang, Yuanming; Li, Weicong; Chen, Junze; Lee, Jae Sung et al. · Nat Commun · 2024

basic_science · Level V

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Abstract

Developing transparent and efficient photoanodes is a challenging but essential task in tandem photoelectrochemical cell for unassisted solar water splitting without an external bias. Here we report construction of p-n homojunction hematite photoanodes by hybrid microwave annealing-induced single antimony doping, which results in the gradually-increased valence states from the surface to the inside by the unique features of hybrid microwave annealing. The Sb-doped p-n homojunction hematite photoanode exhibits improved performance and displays a good transparency, achieving a stable photocurrent density of ~4.21 mA cm<sup>-2</sup> at 1.23 V<sub>RHE</sub> under 100 mW cm<sup>-2</sup> solar irradiation, which is comparable to the reported state-of-the-art hematite photoanodes. More importantly, a parallel-connected stack of six photoanodes of transparent p-n homojunction records a near-theoretical photocurrent density of ~10 mA cm<sup>-2</sup> at 1.23 V<sub>RHE</sub> under standard photoelectrochemical water splitting conditions, which serves as a useful reference for hematite photoanodes and promises its practical application for unbiased photoelectrochemical water splitting.