Engineering Efficient Electrocatalysts: Non-Precious Bimetallic ZIF-Based Hybrid Nanocomposites for Oxygen Reduction Reaction

Synthesis of metal oxides/metal-organic frameworks (MOFs) into hybrid nanocomposites (HNCs), wherein transition metals combined with carbon (C) matrices, due to the excellent conductivity and high porosity present an attractive and cost-effective alternative for engineering electrocatalysts used for oxygen reduction reaction (ORR) in anion exchange membrane fuel cells (AEMFCs). To that end, improving the performance of these materials by adjusting their composition, structure, size, and morphology through an efficient synthesis process is of great technological importance. In this context, the Laser Ablation Synthesis in Solution in Tandem with Galvanic Replacement Reaction (LASiS-GRR) technique is employed as a fast, facile, and green approach for the synthesis, and precise control of complex hierarchical bimetallic Zeolitic Imidazolate Framework (ZIF) structures. Specifically, this novel one-pot, two-step LASiS-GRR process allows for the optimization and of the composition, structure, size, and morphology of Co-based MOFs encapsulated within Zn-based porous MOF crystals “dubbed” Co/ZIF-67@Zn/ZIF-8. The pyrolytic post-processing of these crystals leads to the development of HNCs exhibiting superior ORR electrocatalytic performance in AEMFCs. Overall, this research not only sheds light on the impact of two distinct salt precursors on particle size and morphology during LASiS but also showcases the exceptional performance and stability of post-pyrolytic (ZnO/ZIF@C) HNCs in AEMFC applications as non-precious ORR electrocatalysts when compared to state of art Pt- and platinum-group metals (PGM)-based electrocatalysts.