Engineering Ca-BTC MOF Nanorods with Electrochemical and Luminescent Functionalities

Metal–organic frameworks (MOFs) have emerged as versatile materials for advanced applications due to their exceptional structural diversity, high surface areas, and tunable porosity. Among them, calcium-based MOFs (Ca-MOFs) are attracting significant interest owing to the natural abundance, low cost, and biocompatibility of calcium. In this work, a calcium benzene-1,3,5-tricarboxylate (Ca-BTC) MOF was successfully synthesized and characterized as a multifunctional material. X-ray diffraction confirmed the formation of the crystalline Ca3(BTC)2 phase, in agreement with the simulated pattern derived from the reported single-crystal structure. Electron microscopy revealed a nanorod morphology and ordered crystalline regions at the nanoscale, while Raman spectroscopy provided evidence of Ca–O coordination and the characteristic carboxylate bonding of the BTC linker. Under 365 nm excitation, the Ca-BTC MOF exhibited a bluish-white emission with significantly higher intensity than that obtained under 265 nm excitation, together with an average luminescence lifetime of 51.48 ms and a photoluminescence quantum yield of 7.7%. The higher emission intensity under near-UV excitation highlights its potential as a phosphor for pc-WLED applications. The electrochemical performance of Ca-BTC was evaluated in a solid-state supercapacitor (SC) assembled with graphene-based electrodes and a phosphoric acid electrolyte. Electrochemical measurements demonstrated a specific capacitance of 296.5 F g−1 at 25 mV s−1, together with excellent cycling stability, retaining 97.8% of its initial capacitance after 1000 charge–discharge cycles. These findings demonstrate that the Ca-BTC MOF combines a crystalline structure, long-lived bluish-white luminescence, and electrochemical charge-storage properties, making it a promising candidate for optoelectronic and energy-storage applications.