Effects of hot pressing conditions on the performance of Nafion membranes coated by ink-jet printing of Pt/MWCNTs electrocatalyst for PEMFCs

In our previous work, a hydrothermal method was employed to prepare Pt/MWCNTs nanocomposites with 20 wt.% Pt, a low mean Pt nanoparticles size (2.8 nm) and a specific surface area of 99 m2 g−1. In this work, the membrane electrode assemblies (MEAs) with hydrothermally synthesized Pt/MWCNTs nanocatalysts were fabricated by catalyst-coated membrane (CCM) method. For this purpose, a commercial HP inkjet printer was used to deposit Pt/MWCNTs ink (as catalyst ink) directly on to the substrate (Nafion membrane or decal substrate) with a loading of 0.2 mg cm−2 Pt for both the anode and cathode. The effects of hot-pressing conditions on the performance of MEAs were investigated through Taguchi design of experiments method using temperature (100 and 130 °C), pressure (800 and 1000 psi) and time (3 and 5 min) as effective experimental parameters. The compression ratios of MEAs were determined by testing the thicknesses before and after hot-pressing process. The performance of MEAs was characterized by the polarization curves and cyclic voltammetry (CV) and the surface morphologies of the electrodes were observed by scanning electron microscopy (SEM). The results showed that the most appropriate hot-pressing conditions were 800 psi, 100 °C, and 3 min. Electrochemical analysis and physical property examination revealed that the MEA fabricated by CCM method has a better performance compared to the one prepared by conventional decal transfer (DT) method.

► The MEAs were fabricated using hydrothermally synthesized Pt/MWCNTs nanocatalysts. ► A fabrication technique for CCM by ink-jet printing was developed. ► The most appropriate hot-pressing conditions were found. ► CCM based MEA showed better results compared to CCM-DT based MEA.