Amorphous Co(OH)2 nanocages achieving efficient photo-induced charge transfer for significant SERS activity
Amorphous Co(OH)2 nanocages achieving efficient photo-induced charge transfer for significant SERS activity
复制标题
非晶态 Co(OH)2 纳米笼实现高效光致电荷转移，实现显着的 SERS 活性
DOI：
10.1039/d1tc05770g
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发表时间：
2022
影响因子：
6.4
通讯作者：
Xiaotian Wang
中科院分区：
文献类型：
--
作者：
Jian Yu;CHEN CHAO;Jie Lin;Xiangyu Meng;Lin Qiu;Xiaotian Wang
提高非金属衬底表面增强拉曼散射(SERS)灵敏度的关键是增强衬底-分子间的相互作用，特别是强的振动耦合和高效的光致电荷转移(PICT)跃迁。在这里，通过发展非晶态Co(OH)_2纳米笼(a-Co(OH)_2NC)，我们成功地获得了对靶分子的超高增强因子(1.56×10~5)和超低检测限(10−~10M)。X-射线光电子能谱和电子顺磁共振谱表明，这些a-Co(OH)2纳米碳管比晶态的Co(OH)2纳米碳管具有更多的表面氧缺陷，这导致了大量的表面亚稳态电子态。第一性原理密度泛函理论模拟进一步揭示了表面Co原子的低配位数和表面氧缺陷的丰富促进了a-Co(OH)2与甲基橙(MO)分子之间形成O-Co键和较强的氢键，从而使界面电荷从衬底到MO更容易和有效地转移，从而促进了稳定的表面电荷转移络合物的形成。值得注意的是，a-Co(OH)2较小的带隙有效地改善了衬底-分子的振动耦合，极大地促进了PICT跃迁，增强了拉曼信号强度。这种对非晶态氢氧化物纳米材料显著SERS活性的清晰观察可能为高灵敏和稳定的SERS技术开辟新的前沿。
Boosting substrate–molecule interactions, especially the strong vibronic coupling and efficient photo-induced charge transfer (PICT) transitions, is a critical issue to improve the surface-enhanced Raman scattering (SERS) sensitivity of non-metal substrates. Here, by developing amorphous Co(OH)2 nanocages (a-Co(OH)2 NCs), we succeed in obtaining an ultrahigh enhancement factor (1.56 × 105) and an ultralow limit of detection (10−10 M) for target molecules. X-Ray photoelectron spectroscopy and electron paramagnetic resonance spectroscopy demonstrate that these a-Co(OH)2 NCs possess more surface oxygen defects than the crystalline Co(OH)2, which results in numerous surface metastable electronic states. First-principles density functional theory simulations further reveal that the low coordination number of surface Co atoms and the richness of surface oxygen defects facilitate the formation of O–Co bonds and strong hydrogen bonding between a-Co(OH)2 and methyl orange (MO) molecules, which endow more facile and efficient interfacial charge transfer from the substrate to MO, and thus boost the formation of stable surface charge transfer complexes. Notably, the smaller bandgap of a-Co(OH)2 effectively improves the substrate–molecule vibronic coupling, which greatly promotes PICT transitions and enhances the Raman signal intensity. This clear observation of the remarkable SERS activity of amorphous hydroxide nanomaterials may open up new frontiers for highly sensitive and stable SERS technology.