Fine adjustment of catalyst agglomerate for the controllable construction of Co/Fe–N–C catalyst layers.

Adjusting catalyst/ionomer agglomerate is crucial to a high-performance catalyst layer (CL), particularly for non-precious metal catalysts. As a sacrificial component, the solvent plays a vital role during the CL formation process and resulting microstructure, determining the performance of the anion exchange membrane fuel cells (AEMFCs). Here, solvent mixtures of isopropanol (IPA) and tetrahydrofuran (THF) are studied for the controllable construction of the Co/Fe–N–C CL. The results indicate that the aggregate state of the ionomers and catalysts and the final CL microstructure strongly depend on the ratio of IPA and THF. The CL prepared with IPA: THF = 1:2 (v/v) shows a homogeneous distribution of Co/Fe–N–C catalysts, embedded in the ionomer matrix, due to the fast volatilization and low viscosity of the catalyst ink. The Co/Fe–N–C CL with high moisture adsorption behavior and retention ability results in a high performance AEMFC with peak power density of 545.3 mW cm−2 at 80 °C. The obtained results can guide the rational design of microstructure in non-precious metal CLs for high-performance AEMFCs. [Display omitted] • The influence of mixed solvents on the Co/Fe–N–C catalyst layer is investigated. • The ionomer is beneficial in inhibiting the Co/Fe–N–C aggregation in the inks. • Rapid evaporation results in the rational design of catalyst layer microstructure. • Adjusting the Co/Fe–N–C catalyst layer tunes water adsorption and retention ability. [ABSTRACT FROM AUTHOR]