Electrochemical properties of carbon nanotubes–hydrogenase conjugates Langmuir–Blodgett films

• DOI: 10.1016/j.electacta.2006.09.065
• Publication Date: 2006-11-14T12:18:59Z
• Authors: Ai-Rong Liu; Tatsuki Wakayama; Chikashi Nakamura; Jun Miyake; Nikolay A. Zorin; Dong-Jin Qian
• Keywords: Horizontal scan rate; Indium tin oxide

Abstract We report the preparation of Langmuir–Blodgett (LB) films composed of oxidized carbon nanotubes (CNTs) and hydrogenase (H 2 ase) conjugates and their electrochemical properties. Both single-walled (SWNTs) and multi-walled CNTs (MWNTs) were used to form mixed monolayers with H 2 ase on the Tris–HCl subphase surfaces. By using the LB method, the CNTs–H 2 ase monolayers were transferred onto CaF 2 and indium tin oxide (ITO) electrode surfaces. The LB film modified electrodes showed a couple of waves centered at around −500 mV (versus Ag/AgCl), which corresponding to the redox reaction of [4Fe-4S] 2+/1+ clusters in the H 2 ase. The current intensity was enhanced after co-assembly with CNTs. Because of the different diameters of CNTs, this current intensity was proportional to the scan rate ( υ ) for the electrodes modified with the LB films of pure H 2 ase and SWNTs–H 2 ase, but to the root of scan rate ( υ 1/2 ) for those modified with the MWNTs–H 2 ase LB film. The products of diffusion coefficient and concentration ( D 1/2 C ) increased in the order of pure H 2 ase, SWNTs–H 2 ase, and MWNTs–H 2 ase LB films.