(545d) Laser-Synthesized Core-Shell ZIF-Based Nanocomposites As Efficient Electrocatalysts for Oxygen Reduction Reaction in Anion Exchange Membrane Fuel Cells

Synthesis of metal oxides (MO_x)/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 unique and cost-effective alternatives 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. Therefore, the Laser Ablation Synthesis in Solution in Tandem with Galvanic Replacement Reaction (LASiS-GRR) technique is used as a fast, facile, and environmentally benign 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 of the composition, structure, size, and morphology of Co-based ZIF-67 encapsulated within Zn-based porous ZIF-8 crystals. The pyrolytic post-processing of these crystals leads to the development of HNCs exhibiting superior ORR electrocatalytic performance in AEMFCs. Our research demonstrates not only the impact of two distinct Co salt precursors on particle size and morphology during LASiS but also the exceptional performance and stability of post-pyrolytic (ZnO/ZIF@C) HNCs in AEMFC applications as non-precious-ORR-electrocatalysts compared to state-of-the-art Pt- and platinum-group metals (PGM)-based electrocatalysts.