Enhancement of photocurrent generation by C 60-encapsulated single-walled carbon nanotubes in ru-sensitized photoelectrochemical cell

Abstract

Single-walled carbon nanotubes (SWNTs) and C 60-encapsulated SWNTs (C 60@SWNTs) are introduced to Rusensitized photoelectrochemical cells (PECs), and photocurrents are compared between two cells, i.e., an RuL2(NCS)2/DAPV/SWNTs/ITO cell and an RuL 2(NCS) 2/DAPV/ C 60@SWNTs/ITO cell. [L = 2,2'-bipyridine-4,4'-dicarboxylic acid, DAPV = di-(3-aminopropyl)-viologen, and ITO = indium-tin oxide] The photocurrents are increased by 70.6% in the presence of C 60@SWNTs. To explain the photocurrent increase, the reverse-field emission method is used, i.e., RuL 2 (NCS)2/DAPV/SWNTs/ITO cell (or RuL 2 (NCS) 2/DAPV/ C 60@SWNTs/ITO cell) as an anode and a counter electrode Pt as a cathode in the external electric field. The improved field emission properties, i.e., β (field enhancement factor) and emission currents in the reverse-field emission with C 60@SWNTs indicate the enhancement of the PEC electric field, which implies the improvement of the electron transfer rate along with the reduced charge recombination in the cell.