Impact of catalyst loading, ionomer content, and carbon support on the performance of direct isopropanol fuel cells

Abstract

Liquid Organic Hydrogen Carriers (LOHC) offer a promising solution for hydrogen storage in the existing infrastructure for conventional fuels. Within this framework, the isopropanol/acetone couple as a light-LOHC system is used to generate electricity in a direct isopropanol fuel cell (DIFC). This work focuses on the impact of catalyst loading, ionomer content and catalyst support on the performance of DIFCs. We achieve a performance rise from 95 mW cm -2 to 219 mW cm -2 under air operation by increasing the anode catalyst loading from 0.5 mg cm -2 to 4 mg cm -2 , which can be attributed to the increased abundance of active catalyst sites with higher loadings. In contrast, we find that the cathode loading for the oxygen reduction reaction (ORR) plays a minor role in the performance of DIFCs. Therefore, the cathode loading can be minimized to decrease the total amount of platinum-group metals and, consequently, to save cost. It was also found that an ionomer content of 30% on the anode side is optimal. Additionally, different carbon supports were investigated, where advanced high surface area carbon support showed superior performance to Vulcan with an increase of 20% in power density, motivating the development of new carbon supports for DIFCs. • PtRu catalyst loading on the anode is critical for the performance of direct isopropanol fuel cells. • Cathode Pt loading plays a minor role and can be reduced or even exchanged with PGM-free ORR catalysts. • An ionomer content of 30 wt% (I/C 1.07) is optimal for the anode catalyst layer. • Advanced high surface area carbon support leads to record-high power densities with 259 mW cm −2 at 0.55 V and air operation. • Dynamic operation reveals the potential of isopropanol oxidation without catalyst poisoning.