One-step electrodeposited binder-free Co-MOF films and their supercapacitor application

Metal-organic frameworks (MOFs) with redox-active metal ions and a variety of organic linkers have been widely investigated as prospective electrode materials for supercapacitors. Here, we generate uniformly dense spherical particles on a nickel foam substrate by a simple and binder-free one-step electrodeposition method by adjusting the deposition conditions. The active cobalt in the Co-MOF thin films can provide a large number of redox sites for the electrochemical reaction, while the uniform binder-free Co-MOF structure can keep enough contact area with the electrolyte to reduce the ion transport resistance. As-prepared CTB-0.9 (Co-MOF with a deposition voltage of − 0.9 V) thin film has a specific capacitance of 797.5 F g⁻¹ at a current density of 1 A g⁻¹, exhibiting excellent electrochemical properties. An asymmetric supercapacitor with CTB-0.9 as the positive material and activated carbon as the negative material also demonstrates competitive electrochemical performances, which has a high energy density of 34.3 Wh Kg⁻¹ at a power density of 36,317.6 W Kg⁻¹. This work may open up an effective approach to realize the electrosynthesis of Co-MOF films, promoting the utilization of Co-based MOFs in energy storage and conversion fields.