Abstract
ABSTRACTNoble metal nanoparticles (NPs) modified electrodes have shown promising applications in the areas of catalysis, (electro)chemical analysis and biosensing due to their unique characters. In this paper, we introduced a so-called ligand exchange method to prepare self-assembly (SAM) electrode modified with noble metal nanoparticles. The noble metal nanoparticles protected by weakly adsorbed tetraoctylammonium bromide (TOAB) were synthesized firstly, then self-assembly (SAM) dithiol-modified Au electrode (Au-SHSAM) was immersed into the solutions containing TOAB-protected nanoparticles. Due to the strong interaction between the dithiol groups on the electrode and noble metal nanoparticles, the weakly adsorbed TOAB on the surface of noble metal NPs were replaced by dithiol groups. As a result, the TOAB protected NPs were anchored on the Au-SHSAM template electrode surface by ligand exchange, obtaining noble metal NPs modified electrode with high quality and stability. By adjusting the soaking time, the coverage of nanoparticles on the Au-SHSAM electrode surface could be controlled. The morphology and distribution of noble metal NPs on Au-SHSAM surface was analysis by scanning tunneling microscope (STM), and their electrochemical property was studied by cyclic voltammetry (CV) in H2SO4 solution. The approach is proved as a universal way to prepare noble metal NPs modified SAM electrode.
Highlights
Noble metal nanomaterials have some unique properties in the field of electronics, magnetics and optics [1,2,3]
The surface of the electrode is modified with thiol first, and noble metal NPs protected by weak-adsorbed ligands (such as tetraoctylammonium bromide (TOAB)) were anchored on the thiol modified electrode by ligand exchange
Ultrapure N2 was purged into the solutions for 30 min before electrochemical test to get rid of dissolved O2, during the electrochemical test, the N2was keep purged above the solution to maintain the inert gas atmosphere. cyclic voltammetry (CV) was performed in solution containing 0.5 mol/L H2SO4 and 0.05 mol/L Ru(NH3)6Cl3, the scan rate is 50 mV/s
Summary
Noble metal nanomaterials have some unique properties in the field of electronics, magnetics and optics [1,2,3]. The surface of the electrode is modified with thiol first, and noble metal NPs protected by weak-adsorbed ligands (such as tetraoctylammonium bromide (TOAB)) were anchored on the thiol modified electrode by ligand exchange. In this way, NPs modified electrode with high activity and stability can be achieved. The TOAB-protected metal NPs were assembly onto Au-SHSAM template electrode by strong interaction between metal NPs and mercapto groups In this way, the electrode was successfully modified with noble metal NPs such as Au, Ag, Pt and Pd NPs. We investigated the factors that influence the quanlity of as-prepared modified electrode. Transmission electron microscope (TEM; Hitachi TEM-2100/UHR) was used to characterize the morphology and structure of NPs, scanning tunneling microscope (STM) was used to characterize the surface morphology of electrode by constant current mode with Pt-Ir tip
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