Radiation synthesis of lanthanide-based conductive metal-organic framework 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 confirmed the successful synthesis of Ho-HHTP, while high-resolution transmission electron microscopy revealed its ultrathin nanosheet-like morphology and well-defined one-dimensional channel architecture. Cyclic voltammetry 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. Electrochemical measurements further demonstrated a high specific capacitance of 215.5 F/g at 1 A/g, along with robust rate capability—retaining substantial capacitance even at elevated current densities. Electrochemical impedance spectroscopy 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.