Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721 302, India.
J Colloid Interface Sci. 2011 Jan 15;353(2):506-11. doi: 10.1016/j.jcis.2010.09.080.
We describe a facile route for the one-pot room temperature synthesis of anisotropic Au nanostructures in aqueous solution in the absence of seeds or surfactants and their electrocatalytic activity. The Au nanostructures were synthesized using piperazine derivatives 1-(2-hydroxyethyl)piperazine and 1,4-Bis(2-hydroxyethyl)piperazine as reducing agents. The Au nanostructures were characterized by spectral, transmission electron microscopic (TEM), X-ray diffraction and electrochemical measurements. The absorption spectrum of colloidal nanoparticles displays two bands ~580 and ~930 nm, corresponding to the dipole and quadrupole plasmon resonance, respectively. TEM measurements show that the Au nanostructures have penta-twined polyhedral shape with an average size of 52 nm. X-ray and selected area electron diffraction patterns reveal the existence of face centered cubic nanocrystalline Au. The concentration of Au(III) controls the stability of the nanoparticles. The nanoparticles were immobilized on 3-D silicate network pre-assembled on a conducting support to examine their electrocatalytic activity. The nanoparticle-based electrochemical interface was characterized by spectral, voltammetric and impedance measurements. The nanoparticle shows high catalytic activity in the oxidation of NADH and reduction of oxygen. Unique inverted 'V' shape voltammogram was obtained for the oxidation of NADH at less positive potential. The nanoparticle-based interface favors two-step four-electron reduction of oxygen to water in neutral pH. Significant decrease in the overpotential for the oxidation of NADH and reduction of oxygen with respect to the polycrystalline Au electrode was observed. The electrocatalytic performance of the polyhedral nanoparticle is compared with the conventional citrate stabilized spherical nanoparticles.
我们描述了一种在没有种子或表面活性剂的情况下，在水相中将各向异性 Au 纳米结构在室温下一锅法合成的简便方法，以及它们的电催化活性。该 Au 纳米结构是使用哌嗪衍生物 1-(2-羟乙基)哌嗪和 1,4-双(2-羟乙基)哌嗪作为还原剂合成的。通过光谱、透射电子显微镜（TEM）、X 射线衍射和电化学测量对 Au 纳米结构进行了表征。胶体纳米粒子的吸收光谱显示出两个带580nm 和930nm，分别对应于偶极和四极等离子体共振。TEM 测量表明，Au 纳米结构具有五重孪晶多面体形状，平均尺寸为 52nm。X 射线和选区电子衍射图案表明存在面心立方纳米晶 Au。Au(III)的浓度控制着纳米粒子的稳定性。纳米粒子被固定在 3-D 硅酸盐网络上，该网络预先组装在导电支撑体上，以研究它们的电催化活性。通过光谱、伏安法和阻抗测量对基于纳米粒子的电化学界面进行了表征。纳米粒子在氧化 NADH 和还原氧气方面表现出高催化活性。在更正的电势下，获得了 NADH 氧化的独特倒“V”形伏安图。基于纳米粒子的界面有利于在中性 pH 值下，氧气通过两步四电子还原为水。与多晶 Au 电极相比，观察到 NADH 氧化和氧气还原的过电位显著降低。多面体纳米粒子的电催化性能与传统的柠檬酸稳定的球形纳米粒子进行了比较。
