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Design Predictions of n–n Heterojunction Based Photoanode for Efficient Unbiased Overall Solar Water Splitting
Energy Technology ( IF 3.6 ) Pub Date : 2021-09-03 , DOI: 10.1002/ente.202100570
Kentaro Hatagami 1 , Fuminao Kishimoto 1 , Yudai Kawase 1 , Tomohiro Higashi 1 , Vikas Nandal 2 , Kazuhiko Seki 2 , Kazuhiro Takanabe 1
Affiliation  

There are multiple requirements for maximizing the efficiency of photoelectrochemical overall water splitting using a single n-type semiconducting photoanode. Many visible-light-responsive photoanode materials have been developed but overall water splitting by such materials without external bias has hardly been demonstrated. Herein, the aim is to scale the impact of performance improvement by an n–n heterojunction photoanode comprising an n-type thin modification surface layer over an n-type photon absorber, using a finite element method. For the n-type photon absorber, the semiconductor properties are initially set to those of a well-studied visible–light-absorbing Ta3N5, and key properties are varied. It is demonstrated that an appropriate donor density and thickness of the thin surface layer induce adequate energy band bending in the photon absorber, resulting in a dramatic reduction of the onset potential of the photoanode. Thus, even though the quality of the photoanode is poor (e.g., the donor density is high (≈1 × 1019 cm−3)), the optimized surface layer enables the n–n heterojunction photoanode to facilitate bias-free solar water splitting. These exhaustive investigations could provide design guidelines for obtaining effective photoanodes using an n-type surface modification layer, such as cocatalysts and hole collection layers.

中文翻译:

基于 n-n 异质结的光电阳极的设计预测,用于高效无偏的整体太阳能水分解

使用单个 n 型半导体光阳极最大限度地提高光电化学整体水分解的效率有多种要求。已经开发了许多可见光响应光阳极材料,但几乎没有证明这种材料在没有外部偏置的情况下整体分解水。在此,目的是使用有限元方法来衡量 n-n 异质结光电阳极对性能改进的影响,该光电阳极包括 n 型光子吸收器上的 n 型薄改性表面层。对于 n 型光子吸收剂,半导体特性最初设置为充分研究的可见光吸收 Ta 3 N 5 的特性,并且关键属性各不相同。结果表明,适当的施主密度和薄表面层的厚度会在光子吸收体中引起足够的能带弯曲,从而显着降低光阳极的起始电位。因此,即使光阳极的质量很差(例如,供体密度很高(≈1 × 10 19  cm -3)),优化的表面层使 n-n 异质结光阳极能够促进无偏置的太阳能水分解. 这些详尽的研究可以为使用 n 型表面改性层(例如助催化剂和空穴收集层)获得有效的光阳极提供设计指南。
更新日期:2021-09-03
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