Nanoscale semiconductor/catalyst interfaces in photoelectrochemistry.,Nature Materials

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Nanoscale semiconductor/catalyst interfaces in photoelectrochemistry.
Nature Materials ( IF 37.2 ) Pub Date : 2019-10-07 , DOI: 10.1038/s41563-019-0488-z
Forrest A L Laskowski ₁ , Sebastian Z Oener ₁ , Michael R Nellist ₁ , Adrian M Gordon ₁ , David C Bain ₁ , Jessica L Fehrs ₁ , Shannon W Boettcher ₁

Affiliation

Semiconductor structures (for example, films, wires, particles) used in photoelectrochemical devices are often decorated with nanoparticles that catalyse fuel-forming reactions, including water oxidation, hydrogen evolution or carbon-dioxide reduction. For high performance, the catalyst nanoparticles must form charge-carrier-selective contacts with the underlying light-absorbing semiconductor, facilitating either hole or electron transfer while inhibiting collection of the opposite carrier. Despite the key role played by such selective contacts in photoelectrochemical energy conversion and storage, the underlying nanoscale interfaces are poorly understood because direct measurement of their properties is challenging, especially under operating conditions. Using an n-Si/Ni photoanode model system and potential-sensing atomic force microscopy, we measure interfacial electron-transfer processes and map the photovoltage generated during photoelectrochemical oxygen evolution at nanoscopic semiconductor/catalyst interfaces. We discover interfaces where the selectivity of low-Schottky-barrier n-Si/Ni contacts for holes is enhanced via a nanoscale size-dependent pinch-off effect produced when surrounding high-barrier regions develop during device operation. These results thus demonstrate (1) the ability to make nanoscale operando measurements of contact properties under practical photoelectrochemical conditions and (2) a design principle to control the flow of electrons and holes across semiconductor/catalyst junctions that is broadly relevant to different photoelectrochemical devices.

中文翻译：

光电化学中的纳米级半导体/催化剂界面。

在光电化学装置中使用的半导体结构（例如，薄膜，金属丝，颗粒）通常用纳米颗粒修饰，这些纳米颗粒催化燃料形成反应，包括水氧化，氢气析出或二氧化碳还原。为了获得高性能，催化剂纳米粒子必须与下面的吸光半导体形成电荷-载流子选择性接触，在阻止相反的载流子收集的同时，促进空穴或电子转移。尽管此类选择性接触在光电化学能量转换和存储中起着关键作用，但对底层纳米级界面的了解却很少，因为直接测量其性质非常困难，尤其是在操作条件下。使用n-Si / Ni光阳极模型系统和电位感应原子力显微镜，我们测量了界面电子转移过程，并绘制了在纳米半导体/催化剂界面的光电化学氧逸出过程中产生的光电压。我们发现在器件操作过程中，当周围的高势垒区发展时，通过产生与纳米级尺寸相关的夹断效应，可以增强低肖特基势垒n-Si / Ni接触孔的选择性。因此，这些结果证明了（1）在实际的光电化学条件下进行接触性能的纳米级操作测量的能力，以及（2）控制电子和空穴流经半导体/催化剂结的流量的设计原理，该原理与不同的光电化学装置广泛相关。

更新日期：2019-10-07

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