Application of low-voltage electrophoretic deposition to fabrication of direct methanol fuel cell electrode composite catalyst layer

In this study, the application of a low-voltage electrophoretic deposition (EPD) approach to the fabrication of DMFC electrode composite (i.e., catalyst/ionomer) catalyst layers using a CNT-supported PtRu (PtRu/CNT) anode nanocatalyst was investigated. In the operation of EPD, the PtRu/CNT electrocatalyst was first well mixed with a suitable amount of Nafion^® solution (ionomer dispersion) with or without the addition of HClO₄ as a supporting electrolyte and then electrophoretically deposited onto a non-catalyzed electrode base at a low applied DC voltage range of 0–5 V for 0–60 min. The resultant composite catalyst layer appeared to be thin and quite smooth exhibiting a lustrous texture particularly when the supporting electrolyte was employed in the suspension. Electrochemical impedance spectroscopy (EIS), however, showed that the coated composite catalyst layer exhibited a fairly high resistance indicating an excessive amount of ionomer was preferably deposited. Application of the fabricated electrode to a DMFC resulted in a cell performance with low but reasonable power density. These test results suggested that the low-voltage EPD could be a feasible approach to effective fabrication of DMFC electrode composite catalyst layers incorporated with CNT-supported electrocatalysts, although significant improvements are deemed to be necessary.