Electrochemical activity and stability of Pt catalysts on carbon nanotube/carbon paper composite electrodes

This article reports a facile microwave-assisted approach to synthesize Pt catalysts on carbon nanotube (CNT)/carbon paper (CP) composite through catalytic chemical vapor deposition. The Pt deposits, with an average size of 3–5 nm were uniformly coated over the surface of oxidized CNTs. The electrochemical activity and stability of the Pt–CNT/CP electrode were investigated in 1 M H₂SO₄ using cyclic voltammetry (CV) and ac electrochemical impedance spectroscopy. The Pt catalysts showed not only fairly good electrochemical activity (electrochemically active surface area) but also durability after a potential cycling of >1000 cycles. The analysis of ac impedance spectra associated with equivalent circuit revealed that the presence of CNTs significantly reduced both connect and charge transfer resistances, leading to a low equivalent series resistance ˜0.22 Ω. With the aid of CNTs, well-dispersed Pt catalysts enable the reversibly rapid redox kinetic since electron transport efficiently passes through a one-dimensional pathway. Thus, the CNTs do not only serve as carbon support, they also charge transfer media between the Pt catalysts and the gas diffusion layer. The results shed some light on the use of CNT/CP composite, offering a promising tool for evaluating high-performance gas diffusion electrodes.