Ying Li,Kang Liu,Xin Li,Xuan Jin,Jinze Lyu,Yuebing Xu,Haiyan Zhu,Gang Shi
It is difficult for metal-modified semiconductor nanotubes to obtain surface-enhanced Raman scattering (SERS) substrates through long-range ordered 3D assembly, which adversely affects both Raman signal enhancement and Raman signal uniformity. Here, ZnFe 2 O 4 nanotubes with Ag nanoparticles modified on the inner and outer walls are induced to grow on the surface of the ordered Si pyramid by ZnO nanonedles as sacrificial templates. In this way, the composite nanotubes (Ag/ZnFe 2 O 4 ) are assembled into dandelion flower-like 3D aggregates with a periodic arrangement of hexagonal close packing. This 3D ordered SERS substrate based on Ag/ZnFe 2 O 4 nanotubes has excellent anti-reflective performance and carrier separation ability, which is conducive to the enhancement of Raman signal. When the SERS substrate is used as a sensor, it can achieve the single molecule (10 −13 M) detection level of Rhodamine 6 G, the enhancement factor (EF) is 3.14 × 10 9 , and the linear fit (R 2 ) of quantitative analysis is as high as 0.998 from 10 −13 to 10 −4 M. Meanwhile, the long-range ordered arrays on the SERS substrate can ensure the signal uniformity of sensor, which relative standard deviation (RSD) is as low as 3.37 %. In addition, the photocatalytic self-cleaning capability of SERS substrate ensures that the sensor can be reused. Finally, the mechanism of the photogenerated carrier migration of Ag/ZnFe 2 O 4 and its contribution to Raman signal enhancement were analyzed.
Cuicui Ling,Min Cao,Xin Xue,Tuo Zhang,Bingxin Feng,Qingzhong Xue,Chuanke Wang,Haipeng Lu,Wenpeng Liu
Two-dimensional (2D) materials are significant in the next generation of optoelectronics due to their unique advantages such as thickness-tailored band gaps, mechanical flexibility, and high carrier mobility. However, the conventional fabrication of large-scale and high-quality 2D materials is a laborious complication, thus limiting their wide application. Here, we demonstrate the large-scale fabrication method of vertically standing In 2 S 3 nanosheets on a pyramidal Si array surface and develop the In 2 S 3 /Silicon (Si) heterojunction photodetector with a wide-spectrum response from 365 nm to 980 nm. The efficient photoelectric conversion of heterojunction is attributed to the enhanced light absorption ability of pyramidal Si and vertically standing In 2 S 3 nanosheets due to the large specific surface-to-volume ratio and the multiple light reflections, and the interface barrier originated from the difference of Fermi level between In 2 S 3 and Si at the junction. As a result, the In 2 S 3 /Si heterojunction photodetector has a detectivity of ∼ 1.04 × 10 14 Jones, a responsivity of ∼ 200 A W −1 , a sensitivity of ∼ 1.74 × 10 5 cm 2 W −1 , and a rise time/delay time of ∼ 72/415 µs. We prospect that large-scale synthesis of vertically standing In 2 S 3 nanosheets/pyramidal Si array heterojunction has immense potential in energy and material development, biomedicine, and other applications.
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