TiO2电极表面氰基吡啶吸附的电化学SERS光谱

采用基于核壳纳米粒子的壳层隔绝纳米粒子增强拉曼(SHINERS)以及Au纳米粒子增强技术, 对比研究了4-氰基吡啶(4-CNPy)在TiO2表面的吸附行为. 结果表明, 采用2种技术所获得的光谱存在明显的差别. 利用前者得到了4-CNPy在TiO2电极上随电极电位变化的吸附方式. 在电位为0时, 分子以吡啶环上的N垂直吸附; 随电位负移, 部分分子变为倾斜吸附, 且在电位为-1.0 V时倾斜角度变大. 在正电位区间, 分子始终以吡啶环上的N垂直吸附. 而采用Au纳米粒子滴加在TiO2电极上的方式, 则得到吸附在TiO2, Au及TiO2/Au复合结构上的总光谱信息.

Electrochemical SHINERS Spectroscopic Studies on Adsorption of 4-CNPy at TiO2 Electrodes

Based on the shell-isolated nanoparticles-enhanced Raman spectroscopy(SHINERS) and naked Au nanoparticles SERS technology, the adsorption behavior of 4-cyanopyridine(4-CNPy) on a TiO2 electrode was investigated. The difference in the spectral features from SHINERS and SERS was observed. The SHINERS results showed that the adsorption orientation of 4-CNPy changed with the applied potential. At the potential of 0 V, the 4-CNPy molecules adsorbed on TiO2 electrode by the N atom of pyridine ring in a vertical orientation. With the potential moving to more negative potential, partial molecules turned to a tilted mode. At -1.0 V, the angle of the tilted mode to the vertical line becomes large. At the potential above 0 V, it keeps constant as a vertical orientation by the N atom of pyridine. When the naked Au nanoparticles were attached to the TiO2 electrode, the obtained spectra were originated from the probe molecules adsorbed on the TiO2, naked Au nanoparticles and the TiO2/Au composition. It is difficult to distinguish the contribution of different adsorption sites.