Nanoscale semiconductor/catalyst interfaces in photoelectrochemistry
Nanoscale semiconductor/catalyst interfaces in photoelectrochemistry
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DOI：
10.1038/s41563-019-0488-z
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发表时间：
2020-01-01
期刊：
影响因子：
41.2
通讯作者：
Boettcher, Shannon W.
中科院分区：
文献类型：
--
作者：
Laskowski, Forrest A. L.;Oener, Sebastian Z.;Boettcher, Shannon W.
用于光电化学装置的半导体结构（例如，薄膜、电线、粒子）通常用纳米颗粒装饰，这些纳米颗粒催化燃料形成反应，包括水氧化、氢析出或二氧化碳还原。为了获得高性能，催化剂纳米颗粒必须与底层的光吸收半导体形成电荷载流子选择性接触，促进空穴或电子转移，同时抑制相反载流子的收集。尽管这种选择性接触在光电化学能量转换和存储中起着关键作用，但由于其性质的直接测量具有挑战性，特别是在操作条件下，人们对其潜在的纳米级界面知之甚少。利用n-Si/Ni光阳极模型系统和电位传感原子力显微镜，我们测量了界面电子传递过程，并绘制了纳米级半导体/催化剂界面上光电化学析氧过程中产生的光电压。我们发现，在器件运行过程中，当周围的高势垒区域形成时，通过纳米级尺寸相关的掐断效应，低肖特基势垒n-Si/Ni接触孔的选择性得到增强。因此，这些结果证明了(1)在实际光电化学条件下对接触性质进行纳米级操作测量的能力；(2)控制半导体/催化剂结上电子和空穴流动的设计原则，这与不同的光电化学器件广泛相关。
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.