Guangliang Niu,Fangyan Liu,Yun Yang,Yunzhi Fu,Wei Wang
Multimetallic nanomaterials have many applications. The controlled synthesis of multimetallic nanomaterials is highly desired. We report a study on using penta-fold twinned (PFT) Au nanorods (NRs) as seeds to synthesize PFT Pd-Au-Pd segmental NRs. The results show that the different crystal structures of seeds, I − and cetyltrimethylammonium bromide (CTAB) significantly affect the deposition of Pd on seeds surface. The PFT Pd-Au-Pd segmental NRs showed excellent surface-enhanced Raman scattering (SERS) performance and improved catalytic activity. Our research is of great significance for the synthesis of similar nanostructures, and we also shown that PFT Pd-Au-Pd segmental NRs might have potential applications in studying the process of organic reaction.
Ye Cui,Zhong Xia,Wang Min-Qiang,Chai Yaqin,Yuan Ruo
A glassy carbon electrode (GCE) was modified with a nanocomposite consisting of tetraoctylammonium bromide (TOAB), C 60 fullerene, and palladium nanorods (PdNRs). The PdNRs were hydrothermally prepared and had a typical width of 20 ± 2 nm. The nanocomposite forms stable films on the GCE and exhibits a reversible redox pair for the C 60 /C 60
− system while rendering the surface to be positively charged. The modified GCE was applied to fabricate an electrochemical biosensor for detecting acetylcholinesterase (AChE) by measurement of the amount of thiocholine formed from acetylthiocholine, best at a working voltage of −0.19 V (vs. SCE). The detection scheme is based on (a) measurement of the activity of ethyl paraoxon-inhibited AChE, and (b) measurement of AChE activity after reactivation with pralidoxime (2-PAM). Compared to the conventional methods using acetylthiocholine as a substrate, the dual method presented here provides data on the AChE activity after inhibition and subsequent reactivation, thereby yielding credible data on reactivated enzyme activity. The linear analytical range for AChE activity extends from 2.5 U L −1 to 250 kU·L −1 , and the detection limit is 0.83 U L −1 .
Cyclovoltammetric acetylcholinesterase (AChE) activity assay is constructed based on the palladium nanorods composited with functionalized C 60 fullerene (PdNR/C 60 + TOAB), which aims to measure the signal change between ethyl paraoxon-inhibited and subsequent pralidoxime (2-PAM)-reactivated AChE activity.
Oxidative etching possesses an enriched flexibility and atomic-level accuracy in tailoring the size, morphology, surface structure, and composition of colloidal nanocrystals toward their catalytic and sensing applications. In this work, we choose one-dimensional penta-twinned Pd nanorods as a model system and apply liquid cell transmission electron microscopy (LCTEM) to investigate the detailed nanoscale etching process under different solution environments, which are DI water/e-beam (weakly oxidative), sodium chloride (NaCl) solution/e-beam (moderately oxidative), and ferric chloride (FeCl3) solution/e-beam (strongly oxidative), respectively. Increasing the oxidative strength of solution alone accelerates the dissolution kinetics and drives the system from the (near)-equilibrium etching, where nanorods appear in flat and low-indexed ends (for DI water/e-beam) to nonequilibrium etching with slender tips formed as intermediate products (for FeCl3/e-beam). Under a nonequilibrium etching condition, both symmetric and asymmetric etching occurred, that is, the penta-twinned structure either retained (for symmetric etching) or dissolved to a fourfold-, threefold-, and twofold-twinned and single-crystalline structure (for asymmetric etching), depending on the structural defects-induced strain distribution. The formation of slender tips of different structures can be further understood via energetic analysis and strain relaxation. In particular, in situ LCTEM results were successfully reproduced by flask system-based etching experiments; hence, direct correlations were built between LCTEM and conventional colloidal etching reactions. This work comprehends the present understanding on the synergetic roles of structure characteristics and solution chemistry for the etching of multiply twinned nanoparticles toward their precise controlled synthesis and practical applications.
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