Particle size dependence of the charging of Au nanoparticles immobilized on a modified ITO electrode
Particle size dependence of the charging of Au nanoparticles immobilized on a modified ITO electrode
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DOI：
10.1016/j.electacta.2007.10.024
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发表时间：
2008
影响因子：
6.6
通讯作者：
A. Toyota;T. Sagara
中科院分区：
文献类型：
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作者：
A. Toyota;T. Sagara
柠檬酸盐稳定的金纳米粒子（Au-NPs）具有四种不同的直径（3.7、11.0、21.7和40.8nm）的近球形形状，被固定在4-氨基丁基硅氧烷单层修饰的氧化铟锡（ITO）电极上。从使用电位阶跃序列的库仑测量的结果中，发现在施加电位阶跃之后每个颗粒被转移以达到新的平衡状态的电子数与直径的平方成比例地增加。在-0.4 ~0.6V（Ag/AgCl/sat'd KCl）电位范围内，单位面积的Au-NP表面的双层积分电容约为1000。70μFcm−2，与粒子大小无关。Au-NP表面的微分电容是电势的函数，在0.32V处具有最大值，而该函数再次与颗粒尺寸无关。通过对电势阶跃瞬态电流的分析，讨论了充电动力学。通过恒电位和电位调制透射-吸收光谱测量获得的等离子体激元吸收带的电位依赖性位移显示，当施加更多的负电位时，较小的Au-NP表现出更大的等离子体激元带的蓝移，与Mie-Drude理论一致。
Citrate-stabilized gold nanoparticles (Au-NPs) of a nearly spherical shape with four different diameters (3.7, 11.0, 21.7, and 40.8nm) were immobilized on a 4-aminobutylsiloxane monolayer-modified indium-tin oxide (ITO) electrode. From the results of coulometric measurements using potential step sequences, the number of electrons per particle to be transferred to attain a new equilibrium state after applying a potential step was found to increase in proportion to the square of the diameter. The double layer integral capacitance of the Au-NP surface per unit area in the potential range from −0.4 to 0.6V (Ag/AgCl/sat’d KCl) is ca. 70μFcm−2, being independent of the particle size. The differential capacitance of the Au-NP surface is a function of the potential with a maximum at 0.32V, while the function is again independent of the particle size. The kinetics of the charging was discussed using the analysis of the potential step transient current. The potential-dependent shift of the plasmon absorption band obtained by constant-potential and potential-modulated transmission–absorption spectroscopic measurements revealed that a smaller Au-NP exhibits a greater blue-shift of the plasmon band when applying more negative potentials, being in line with the Mie–Drude theory.