Power Generation Characteristics of the Direct Formic Acid Fuel Cell Using Silica Containing Carbon Nanofiber as the Anode Supports

Abstract

Direct formic acid fuel cells, DFAFCs, have received considerable attention due to their higher power density in the direct liquid fuel cells. Recently, 550 mW/cm2 of power density at 30 oC was reported by Chan et al. using Pd–Ni2 P/C catalyst for DFAFC anode [1]. In order to obtain the higher power density, the operation temperature of DFAFC should be elevated since anode and cathode reaction kinetics increases with the increasing operation temperature, however, it has been known that the power density of DFAFC above 50 oC showed plateau with the increasing temperature. As a reason of the plateau in the power desnity above 50 oC, the increase of the mass transport loss was considered [2]. Therefore, controlling the mass transport in the catalyst layer is one of the key factor to obtain high power density. In this context, the silica embedded carbon nanofiber, SECNF, support for DFAFC anode have been suggested in this study. By using SECNF as a catalyst support, both of the high porosity catalyst layer which can enhance the mass transport rate in the catalyst layer and the high catalystic activity due to the support metal effect of the silica have been expected. It was found that the formic acid oxidation reaction activity significantly increased by using SECNF as a support of Pd comparing to conventional Pd/CNF and Pd/C due to the support effect of the SiO2. Moreover, the high porosity anode electrode could be successfully fabricated by using Pd/SECNF. On the other hand, the power density of DFAFC was not enhanced due to thick catalyst layer. In the presentation, the effect of the porosity and thickness of catalyst layer on the anode mass transport loss and power generation characteristics will be discussed in detail. Reference [1] J. Chang, L. Feng, C. Liu, W. Xing, and X. Hu, Angew. Chemie Int. Ed., 53, 122–126 (2014). [2] T. Tsujiguchi, F. Matsuoka, Y. Hokari, Y. Osaka, and A. Kodama, Electrochim. Acta, 197, 32–38 (2016)