Radiation Synthesis of Lanthanide-Based Conductive MOFs and Their Pseudocapacitive Performance

In this study, a lanthanide-based conductive metal–organic framework (Ho-HHTP) was synthesized via gamma-ray irradiation technology and systematically evaluated for its pseudocapacitive behavior. Powder X-ray diffraction (PXRD) confirmed the successful synthesis of Ho-HHTP, while high-resolution transmission electron microscopy (HRTEM) revealed its ultrathin nanosheet-like morphology and well-defined one-dimensional channel architecture. Cyclic voltammetry (CV) analysis showed typical symmetric redox peaks indicating dominant surface-controlled pseudocapacitive charge storage. Quantitative kinetic analysis revealed that the pseudocapacitive contribution accounted for 82.18% of the total capacitance at a scan rate of 30 mV s-1. Electrochemical measurements further demonstrated a high specific capacitance of 215.5 F g-1 at 1 A g-1, along with robust rate capability—retaining substantial capacitance even at elevated current densities. Electrochemical impedance spectroscopy (EIS) indicated low ohmic resistance (~2.5 Ω) and charge-transfer resistance (~3.8 Ω), corroborating efficient interfacial charge transfer and rapid ion diffusion kinetics. Collectively, this work presents a radiation-enabled synthetic route for lanthanide-based conductive MOFs and establishes Ho-HHTP as a highly promising electrode material for next-generation supercapacitors.