Fig 1

(a) Line charts of the variation trend in length and width of the Au NRs with the decreasing [Au-NP seed] at a fixed [AgNO3]. (b, c) Line charts of variations in width (b) and length (c) of the Au NRs with the increasing [AgNO3]. The [CTAB], [HAuCl4], [Hydroquinone] ([HQ]), [H+], and [Au-NP seeds] are 100 mmol∙L−1, 0.46 mmol∙L−1, 4.60 mmol∙L−1, 2.51 mmol∙L−1, and 8.4 × 1012 particles∙mL−1, respectively."

Scheme 1

Schematic representation of the possible structures of CTAB micelles before (a) and after (b–d) the addition of LA molecules. The compactness of CTAB molecules in the mixed CTAB-LA micelles would increase with the increasing [LA]."

Fig 2

TEM images of FW14-Au NRs obtained under different [LA]: 0 (a), 8.3 (b), 12.5 (c), and 14.1 mmol∙L−1 (d). The [CTAB], [HAuCl4], [AgNO3], [HQ], [H+], and [Au-NP seeds] used in the growth solution are 100 mmol∙L−1, 0.46 mmol∙L−1, 0.27 mmol∙L−1, 4.60 mmol∙L−1, 2.51 mmol∙L−1, and 8.4 × 1012 particles∙mL−1, respectively. Note that standard deviations in length and width of Au NRs both are less than 10%."

Table 1

Summarized data of the length (LNR), width (WNR), aspect ratio (AR), volume (VNR) and mass (mNR) of an individual FW14-Au NRs, the total mass of Au added in the growth solution of Au NRs (mAu-total), the particle number (Neffective) of Au-NP seeds that grow into final FW-Au NRs (Neffective = mAu-total/mNR), the total particle number of added Au-NP seeds into the growth solution (Nadded), and the ratio (η = Neffective/Nadded) of the particle number of Au-NP seeds that grow into final FW14-Au NRs (Neffective) to the particle number of added Au-NP seeds (Nadded) for synthesis of FW14-Au NRs under different [LA]."

Fig 3

TEM images of FW23-Au NRs (A) and FW6.5-Au NRs (B) obtained under different [LA]: 0 (a), 8.3 (b), 12.5 (c) and 14.1 mmol∙L−1 (d), respectively. Note that the standard deviations in the length and width of FW-Au NRs are both less than 10%. The [Au-NP seeds] in (A) and (B) is 2.8 × 1012 and 5.6 × 1013 particles∙mL−1, respectively. The [AgNO3] in (A and B) is 0.24 and 0.30 mmol∙L−1, respectively, which is necessary to control SBE of Au-NP seeds. The [CTAB], [HAuCl4], [H+], and [HQ] used in the growth solution are 100, 0.46, 2.51, and 4.60 mmol∙L−1, respectively."

Fig 4

TEM images of FW23-Au NRs (a, b) and FW14-Au NRs (c, d, e). FW23-Au NRs (a, b) were prepared under the fixed [Au-NP seeds] (2.8 × 1012 particles∙mL−1) by adjusting the [HAuCl4] as 0.23 (a) and 0.14 mmol∙L−1 (b). And the corresponding [HQ] for FW23-Au NRs (a, b) is 3.45 and 5.60 mmol∙L−1, respectively. FW14-Au NRs (c, d, e) were prepared under the fixed [Au-NP seeds] (8.4 × 1012 particles∙mL−1) by adjusting the [HAuCl4] as 0.23 (c), 0.18 (d), and 0.14 mmol∙L−1 (e). And the corresponding [HQ] for FW14-Au NRs is 1.84 (c), 1.08 (d), and 0.42 mmol∙L−1 (e). The corresponding [AgNO3] for FW23-Au NRs (a, b) is 0.24 (a) and 0.06 mmol∙L−1 (b), while that for FW14-Au NRs is 0.27 (c), 0.27 (d), and 0.09 mmol∙L−1 (e), respectively. The [CTAB], [LA] and [H+] are 100, 14.1 and 2.51 mmol∙L−1, respectively. Note that the standard deviations of Au NRs' lengths and widths both are less than 10%."

Fig 5

TEM images (a to d) of FW6.5-Au NRs obtained under different [HAuCl4]: 0.23 (a), 0.18 (b), 0.58 (c), and 0.69 mmol∙L−1 (d). The corresponding [HQ] is 1.15 (a), 0.54 (b), 8.55 (c), and 13.8 mmol∙L−1 (d). The [LA] is 14.1 mmol∙L−1 (a, b) and 8.3 mmol∙L−1 (c, d). The [CTAB], [AgNO3], [H+], and [Au-NP seeds] are 100 mmol∙L−1, 0.30 mmol∙L−1, 2.51 mmol∙L−1, and 5.6 × 1013 particles∙mL−1, respectively. Note that the standard deviations of Au NRs' lengths and widths both are less than 10%."