Three-dimensional Cobalt-MOF/ CNF microstructured assembly as a bifunctional electrocatalyst for effective overall water-splitting in alkaline media.

[Display omitted] • A three-dimensional Co-MOF/CNF composite is synthesized via simple ultrasonication. • An excellent electrocatalytic activity of OER and HER: 250 mV and 193 mV at 10 mA/cm2 in 1 M KOH. • A low-cost approach is being developed to produce high-activity electrocatalysts. • Overall water splitting at 10 mA/cm2 was achieved at an overall voltage of 1.49 V. The electrocatalyst Co-MOF/CNF microstructure exhibits excellent stability and charge transfer efficiency synthesized via ultrasonication technique. The composite has a lower Rct value of 2 Ω. The larger Cdl value of Co-MOF/CNF (12.3 mF/dec) is responsible for the high catalytic activity for both HER and OER reactions. The composite has strong catalytic activity in HER and OER, with low overpotentials of 193 mV and 250 mV at 10 mA/cm2. Furthermore, excellent water electrolyzer activity was achieved by Co-MOF/CNF||Co-MOF/CNF with a cell voltage of 1.49 V at 10 mA/cm2 and is stable over 24 h, proving the long-term efficacy in sustainable energy systems. [ABSTRACT FROM AUTHOR]