Indexed by:期刊论文

Date of Publication:2017-10-01

Journal:RUSSIAN JOURNAL OF ELECTROCHEMISTRY

Included Journals:Scopus、SCIE、EI

Volume:53

Issue:10,SI

Page Number:1204-1221

ISSN No.:1023-1935

Key Words:Prussian Blue nanoparticles; electrocatalysis; biological sensors; electron transfer; molecular self-assembly; electron tunneling

Abstract:We have explored interfacial electrochemical electron transfer (ET) and electrocatalysis of 5-6 nm Prussian Blue nanoparticles (PBNPs) immobilized on Au(111)-electrode surfaces via molecular wiring with variable-length, and differently functionalized thiol-based self-assembled molecular monolayers (SAMs). The SAMs contain positively (-NH3 (+)) or negatively charged (-COO-) terminal group, as well an electrostatically neutral hydrophobic terminal group (-CH3). The surface microscopic structures of the immobilized PBNPs were characterized by high-resolution atomic force microscopy (AFM) directly in aqueous electrolyte solution under the same conditions as for electrochemical measurements. The PBNPs displayed fast and reversible interfacial ET on all the surfaces, notably in multi-ET steps as reflected in narrow voltammetric peaks. The ET kinetics can be controlled by adjusting the length of the SAM forming linker molecules. The interfacial ET rate constants were found to depend exponentially on the ET distance for distances longer than a few methylene groups in the chain, with decay factors (beta) of 0.9, 1.1, and 1.3 per CH2, for SAMs terminated by -NH3 (+),-COO-, and-CH3, respectively. This feature suggests, first that the interfacial ET processes follow a tunneling mechanism, resembling that of metalloproteins in a similar assembly. Secondly, the electronic contact of the SAM terminal groups that anchor non-covalently the PBNP are crucial as reported for other types of molecular junctions. Highly efficient PBNP electrocatalysis of H2O2 reduction was also observed for the three linker groups, and the electrocatalytic mechanisms analyzed.