A comparative study on the synthesis strategies and electrochemical features of bimetallic Cu/Co-MOFs†

In this work, three distinct synthetic procedures—step-by-step (CC-1), single-step (CC-2), and simple mixing (CC-3)—were utilized to investigate their effects on the formation of heterostructures in bimetallic Cu/Co-MOFs. The resulting MOF crystal structures revealed a 1 : 1 ratio of Co to Cu metal ions, and compared their electrochemical activities with a simple mixture of individual MOFs. To maximize the benefits of these synthesis approaches for supercapacitor uses, electrochemical analyses were conducted. Results revealed that the capacitance of CC-1 was 438 F g⁻¹ at 1 A g⁻¹, which was 1.14 times and 2.76 times higher than those of the CC-2 and CC-3 samples, respectively. This notable performance was attributed to the synergistic contributions from each 2D material component and the formation of a stable heterostructure that resulted from an optimal metal-ion loading. The best-performing CC-1 electrode was further tested in both asymmetric (AD) and symmetric (SD) coin cell devices. AD demonstrated an energy density (ED) of 40.4 W h kg⁻¹ through a power density (PD) of 302.3 W kg⁻¹ with 75% stability, while the SD device displayed an ED of 15.7 W h kg⁻¹ and a PD of 346.7 W kg⁻¹ with 88% stability.