NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore.
Department of Physics, National University of Singapore, Singapore 117551, Singapore.
Nat Commun. 2017 Apr 19;8:15070. doi: 10.1038/ncomms15070.
Semiconductor compounds are widely used for photocatalytic hydrogen production applications, where photogenerated electron-hole pairs are exploited to induce catalysis. Recently, powders of a metallic oxide (SrNbO, 0.03<x<0.20) were reported to show competitive photocatalytic efficiencies under visible light, which was attributed to interband absorption. This discovery expanded the range of materials available for optimized performance as photocatalysts. Here we study epitaxial thin films of SrNbO and find that their bandgaps are ∼4.1 eV. Surprisingly, the carrier density of the conducting phase exceeds 10 cm and the carrier mobility is only 2.47 cm V s. Contrary to earlier reports, the visible light absorption at 1.8 eV (∼688 nm) is due to the plasmon resonance, arising from the large carrier density. We propose that the hot electron and hole carriers excited via Landau damping (during the plasmon decay) are responsible for the photocatalytic property of this material under visible light irradiation.
半导体化合物被广泛应用于光催化制氢领域，其中光生电子-空穴对被用于诱导催化反应。最近，报道了一种金属氧化物（SrNbO，0.03<x<0.20）的粉末在可见光下表现出竞争的光催化效率，这归因于带间吸收。这一发现扩大了可用于优化性能的光催化剂材料的范围。在这里，我们研究了 SrNbO 的外延薄膜，发现它们的带隙约为 4.1eV。令人惊讶的是，导带的载流子密度超过 10cm，载流子迁移率仅为 2.47cmV/s。与早期的报道相反，在 1.8eV（约 688nm）处的可见光吸收是由于等离子体共振，这是由大的载流子密度引起的。我们提出，通过朗道阻尼（在等离子体衰减期间）激发的热电子和空穴载流子是该材料在可见光照射下具有光催化性能的原因。
