광전기화학적 응용을 위한 탄소나노튜브-산화철 전극에 대한 연구

Abstract

Multi wall carbon nanotube(MWCNT) was applied to an iron oxide-based photoelectrochemical(PEC) cell. Iron oxide has three big advantages as a photocatalyst in an anode of a PEC cell. They are small band gap(about 2.1eV), appropriate band positions, and stability. But iron oxide also has a bad electrical conductivity so that charge recombination largely occurs. On the other hand, CNT shows a good electrical property and can play a role of an expressway for electron transfer. Therefore MWCNT was hired for improving charge separation in an iron oxide-based PEC cell. A layered structure was chosen for MWCNT-iron oxide electrode because MWCNT can obstruct light absorption of iron oxide. But the electrode was made with an entangled interface between MWCNT and iron oxide. In x-ray diffraction(XRD) analysis and UV-Vis spectroscopy, iron oxide had ？朞Vphase and about 2.1eV indirect band gap. Moreover, existence of MWCNT did not affect crystalline property and light absorption characteristic of iron oxide. A MWCNT layer showed a porous net-like structure in images of scanning electron microscopy(SEM). Iron particles were distributed well on a MWCNT layer after e-beam evaporation. A MWCNT-iron oxide layer had a thickness of about 300nm. In linear sweep voltammetry(LSV) and chronoamperometry, MWCNT-modified electrode showed increased photocurrent about 65.7% larger than that of iron oxide electrode at 0.23V vs. Ag/AgCl. This increase is not from MWCNT…s own PEC ability. It may due to reduced charge recombination and a Nyquist plot of MWCNT-modified electrode also shows reduced semicircles. In Mott-Schottky analysis, a positive shift of EFB in MWCNT-modified electrode was observed and it can be an evidence of charge transfer between iron oxide and MWCNT.