Probe Sonication-Assisted Synthesis of a Ni-MOF/V-MOF Composite for an Enhanced Oxygen Evolution Reaction

Abstract The development of cost-effective and highly efficient electrocatalysts for the oxygen evolution reaction (OER) is essential for advancing sustainable hydrogen production via water electrolysis. In this work, Ni-MOF and V-MOF were successfully synthesized using a facile solvothermal method and Ni-MOF/V-MOF composite using a highly efficient probe sonication method. This design allows the successful integration of the Ni and V centers into a hierarchical structure with a porous thin nanoflake architecture. The Ni-MOF/V-MOF composite electrocatalyst achieves a low overpotential of 270 mV at a current density of 10 mA cm−2 in 1 M KOH electrolyte. Moreover, the Tafel slope value was as low as 92 mV dec−1 using LSV measurements, indicating highly accelerated kinetics compared to its monometallic Ni and V counterparts. In addition, the electrocatalyst sustained the OER operation for 250 h under alkaline conditions. Post-stability XPS analyses reveal surface chemical-state changes after a long cycle. This study demonstrates the synergistic effect between the Ni and V centers and enhanced charge-transfer efficiency, evidenced by the smallest charge-transfer resistance (Rct) of 3.20 Ω. This highlights the promising initial activity of the Ni-MOF/V-MOF composite as a cost-effective electrocatalyst for emerging energy conversion technologies.