阐明硒化金纳米结构的结构性质,New Journal of Chemistry

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阐明硒化金纳米结构的结构性质
New Journal of Chemistry ( IF 2.7 ) Pub Date : 2019-03-14 00:00:00 , DOI: 10.1039/c9nj00142e
Lerato F. E. Machogo _{1,

2,

3,

4,

5} , Musa Mthimunye _{1,

2,

3,

4,

5} , Rudo K. Sithole _{1,

2,

3,

4,

5} , Phumlani Tetyana _{1,

2,

3,

4,

5} , Neo Phao _{1,

2,

3,

4,

5} , Grace N. Ngubeni _{1,

2,

3,

4,

5} , Mbuso Mlambo _{5,

6,

7,

8} , Phumlane S. Mduli _{5,

9,

10,

11} , Poslet M. Shumbula _{5,

12,

13,

14} , Nosipho Moloto _{1,

2,

3,

4,

5}

Affiliation

贵金属过渡金属硫属元素化物硒化金是一种相对未开发的层状材料。本文中，我们通过改变胶体合成中前体的添加顺序，报道了多态混合价AuSe（Au ¹⁺ Au ³⁺ Se ₂）的合成和表征。尽管有这些变化，但所有产生的材料均显示出α-和β-AuSe的共存。尽管观察到两种多晶型物，但是XRD显示在较高温度下添加金前体导致α-AuSe成为主导相，而在较低温度下添加导致β-AuSe成为优选相。α-和β-AuSe的晶体结构均由线性键合的Au ¹⁺离子与两个Se原子和一个Au的重复单元组成³⁺离子以方形平面几何形状键合到四个Se原子上。XPS的Au4f核心能级谱仅显示Au⁺¹氧化态，但是，使用Se3d核心能级谱，明显形成了AuSe（Au¹⁺ Au³⁺ Se₂）。使用DFT计算，模拟了α-和β-AuSe的拉曼光谱，并且仅发现正方形平面几何形状具有拉曼活性。属于D _4h点组的方形平面几何形状（Au³⁺ Se₄）^-离子产生三种拉曼主动振动模式，即对称拉伸（A_1g），平面弯曲（B_1g））和α-AuSe的不对称拉伸（B _2g）以及β-AuSe的A _1g和B _1g。实验上，所有样品均显示了两个阶段的拉曼振动线。此外，拉曼光谱法证实在AuSe中存在Au ³⁺，这是使用XPS无法检测到的。从TEM和SEM结果可以看出，主要为α-AuSe的样品的形态为纳米带，而主要为β-AuSe的样品显示为板状结构。主要的α-AuSe样品显示出一个宽吸收带，在853 nm处具有最大值，而主要的β-AuSe样品显示出吸收的证据，但是没有确定的激子峰。

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Elucidating the structural properties of gold selenide nanostructures

Noble transition metal chalcogenide gold selenide is a relatively unexplored layered material. Herein, we report on the synthesis and characterization of polymorphic mixed-valence AuSe (Au¹⁺Au³⁺Se₂) by varying the sequence of the addition of the precursors in a colloidal synthesis. Despite the variations, all produced materials showed the co-existence of α- and β-AuSe. Although both polymorphs were observed, XRD showed that the addition of the gold precursor at higher temperatures resulted in α-AuSe being the dominant phase while the addition at lower temperatures resulted in β-AuSe being preferred. The crystal structures of both α- and β-AuSe consist of repeating units of a linearly bonded Au¹⁺ ion to two Se atoms and a Au³⁺ ion bonded to four Se atoms in a square planar geometry. The Au4f core level spectrum of XPS showed only the Au⁺¹ oxidation state, however, using the Se3d core level spectrum, the formation of AuSe (Au¹⁺Au³⁺Se₂) was evident. Using DFT calculations, the Raman spectra of α- and β-AuSe were simulated and only the square planar geometry was found to be Raman active. The square planar geometry (Au³⁺Se₄)⁻ ions belonging to the D_4h point group produced three Raman active vibrational modes, namely, a symmetric stretch (A_1g), a planar bend (B_1g) and an asymmetric stretch (B_2g) for α-AuSe as well as A_1g and B_1g for β-AuSe. Experimentally, all samples showed Raman vibrational lines from both phases. Moreover, Raman spectroscopy confirmed the presence of Au³⁺ in AuSe which was not detected using XPS. From the TEM and SEM results, it was evident that the morphologies of the predominantly α-AuSe samples were nanobelts while the predominantly β-AuSe samples showed plate-like structures. The predominantly α-AuSe samples showed a broad absorption band with a maximum at 853 nm while the predominantly β-AuSe samples showed evidence of absorption however with no defined excitonic peak.

更新日期：2019-03-14

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