Lanthanum-substituted CaMo-MOF via controlled metal nitrate ratios for Electrochemical Performance

In this study, a series of Lax Ca1-x Mo-based metal-organic frameworks (MOFs), designated as CML1, CML2, CML3 and CML4, were synthesized via a controlled precipitation method. A comprehensive characterization was performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The XRD confirmed the formation of a single-phase tetragonal scheelite-type structure (I41 /a), with no secondary phases detected. The average crystallite size is found to be 54, 52, 42 and 16 (nm) in CML1, CML2, CML3 and CML4 MOFs. The SEM reveals a morphological evolution from irregular granules in CML1 to well- faceted rods in CML4 MOFs. The electrochemical analysis revealed a clear performance hierarchy, with CML3 electrode exhibiting the highest the specific capacitance in a two-electrode system. The coulombic efficiency of 96 % is retained by the CML3 electrode even after 1000 GCD cycles in a two-electrode system.