Thickness Control over Ionomer Coatings on Nano Patterned Three-Phase Zones for a Highly Efficient Electrode

Abstract

In the present study, a carbon nanotube supported platinum (Pt/CNT) electrode with a thin and uniform ionomer layer as the proton-conducting electrolyte on a nano patterned three-phase zone (TPZ) was fabricated, aiming at high electrocatalytic activity and high charge transfer rate for methanol oxidation reaction (MOR). Unlike conventional paste or spray methods that produced thick and non-uniform ionomer layers to form TPZs within the catalyst layers (50-100 μm) of electrodes, thin and uniform ionomer layers (5-10 nm) on the hydrophilic-treated Pt/CNT catalyst electrodes (8 μm) were harvested by spin-coating. The thickness of the ionomer layer was controlled by altering the spin-coating speed, and the effect of the ionomer thickness on the surface of the catalyst layer and on the electrochemical properties of the electrodes for MOR was studied (mass activity, MA and charge transfer resistance, Rct). Compared to the electrode fabricated by spraying (MA: 355 A g −1 , Rct: 48 cm 2 ), the ionomer-coated electrode spin-coated at 4000 rpm exhibited superior properties for MOR (MA: 381 A g −1 , Rct: 15 cm 2 ). The outcome renders this new electrode to embrace potential applications in micro direct methanol fuel cells (μDMFCs) with the design of a thin and uniform TPZ.

Mn-doped nickeltitanate (Ni1−xMnxTiO3) as a promising support material for PdSn electrocatalysts for methanol oxidation in alkaline media

“…To t impedance spectra obtained on the PdSn-MNT/C electrode, R 1 , CPE, R 2 , and W, represents the solution resistance, constant phase elements, charge transfer resistance and Warburg elements that denotes a diffusion process, in the equivalent circuit. 53 As demonstrated in Fig. 9 this charge transfer phenomenon is evaluated for different electrodes for methanol oxidation at 1.0 mol L À1 M À1 methanol.…”