| The gold and palladium nanowires (Au-Pd NWs) were prepared by microbial adsorption - chemical reduction method using Escherichia coli (ECCs) as bio-template, cetyltrimthyl ammonium bromide (CTAB) as a protective agent, and ascorbic acid (AA) as a reducing agent, respectively. The influence of different Au/Pd molar ratios on Au-Pd bimetallic nanowire morphology, and their composition was systematically studied. The as-prepared Au-Pd NWs samples were characterized by SEM, TEM and XRD spectroscopy and other technologies. The results show that the ECCs surface provided preferential nucleation sites, which were vital for growth of bimetallic nanoparticles. Through the adsorption and reduction of ECCs, a small amount of Pd(0) and Au(0) were first reduced in a short time, then a large number of Pd and Au ions were gathered around the surface of the ECCs. Upon AA addition, the reduction reaction was greatly accelerated when the Pd and Au ions on the surface of ECCs were reduced to preferential nuclei in a short time. The interaction between ECCs surface and the nuclei prevents their migration, so the metal nuclei could continue to grow. The chainlike intermediate nanostructures were formed on the cells surface in the direction of CTAB. With the addition of new atoms onto intermediate nanostructures, the small nanoparticles were consumed via Ostwald ripening during the crystallization of the chained nanostructures, thus forming nanowires. Therefore, owing to the synergism between ECCs and CTAB, the growth of one dimensional Au-Pd nanostructures was sufficiently promoted. |
