Two-dimensional layered black phosphorus (BP) with a tunable band gap of 0.3–2.0 eV has received great interest in broad-spectrum-active photocatalysis, but rapid charge recombination limits its potential applications. Herein, we report that BP quantum dots (QDs) work as active photosensitizer in a ternary heterostructure consisting of BP QDs, Au nanorods (NRs), and CdS nanowires (NWs), which efficiently photocatalytically generates H₂ at full solar spectrum, especially in the near-infrared (NIR) region. The superior performance of the BP–Au–CdS heterostructure arises from the overall photoabsorption contribution, the dual role (electron relay and plasmonic electron donor) of Au NRs, as well as the appropriate band alignment and strong coupling between the three components. Tracking the electron and hole transfers via femtosecond transient absorption spectroscopy shows a unidirectional electron flow from BP to Au and then to CdS, which has been achieved by the high conduction band level of BP, the well-harnessed work function match in BP–Au, and the well-established Schottky barrier in Au–CdS heterojunction.

中文翻译：

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黑色磷-Au-CdS异质结构中全太阳光谱激活的光催化H ₂生成的超快电荷分离

具有0.3-2.0 eV可调带隙的二维层状黑磷（BP）在广谱活性光催化中引起了极大的兴趣，但快速的电荷重组限制了其潜在的应用。在这里，我们报道BP量子点（QDs）在由BP QDs，Au纳米棒（NRs）和CdS纳米线（NWs）组成的三元异质结构中作为活性光敏剂，它们有效地光催化生成H _2。在完整的太阳光谱下，尤其是在近红外（NIR）区域。BP–Au–CdS异质结构的优异性能归因于整体光吸收作用，Au NRs的双重作用（电子中继和等离子体电子供体），以及适当的能带排列和三组分之间的强耦合。通过飞秒瞬态吸收光谱跟踪电子和空穴的转移，显示了从BP到Au再到CdS的单向电子流，这是通过BP的高导带能级，BP–Au中良好利用的功函数匹配实现的，以及在Au-CdS异质结中建立的肖特基势垒。