Morphology-controlled synthesis of metal-organic frameworks derived lattice plane-altered iron oxide for efficient trifunctional electrocatalysts

Developing efficient trifunctional electrocatalysts with high activity and long durability is extraordinarily desirable. Metal-organic frameworks (MOFs) are ideal self-sacrificial templates, and their derived electrocatalysts are promising for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Herein, Fe-based MOFs with well-aligned morphologies have been synthesized by elaborately tuning the competitive coordinated cations from diverse metal sources and solvent systems through a one-step solvothermal method. In this process, the competitive coordination with the metal sites between the ligands and the solvent molecules allows the feasibility to regulate the morphologies of these MOF precursors. After pyrolysis, the resulting Fe2O3 compounds not only inherit the morphologies of the precursors, but also expose different active lattice planes, producing disparate intrinsic active sites. Particularly, the concave octahedral (CO)-Fe2O3 with higher active facets and more accessible surface-active sites exhibits a superior electrocatalytic activity and stability for ORR, OER and HER compared with other morphologies and structures. This competitive coordination strategy paves an innovative and feasible pathway for morphology- and structure-controlled MOFs derivatives with tailored catalytic centers toward electrochemical energy storage and convention.