A synergistic perovskite-transition metal carbide hybrids for high-performance supercapacitors

The strategic integration of disparate material classes presents a powerful pathway for engineering advanced electrodes that transcend the performance limitations of individual components. This study demonstrates the rational design of SrFeO₃@Mo₂C and SrFeO₃@W₂C hybrid architectures, which synergistically combine the rapid charge delivery of electric double-layer capacitive carbides with the high specific capacity of Faradaic pseudocapacitive perovskites. Synthesized via a combined chemical reduction and hydrothermal method, the composites were thoroughly characterized, with XPS confirming strong interfacial electronic coupling that facilitates charge redistribution. Electrochemically, the SrFeO₃@Mo₂C hybrid delivered a high specific capacitance of 786 F g⁻¹ at 1 A g⁻¹, significantly outperforming the individual components. Kinetic analysis based on the power-law relationship (i = avᵇ) yielded a b value of ∼0.53, indicating a mixed charge storage mechanism dominated by diffusion-controlled Faradaic processes associated with the SrFeO₃ redox reactions. The Mo₂C conductive scaffold facilitates rapid electron transport and lowers the charge transfer resistance, thereby accelerating the electrochemical reaction kinetics and improving the utilization of active sites. This is further supported by a low charge-transfer resistance from EIS. The hybrid electrode exhibited remarkable cycling stability, retaining 89.2% of its initial capacitance over 5000 cycles. When configured into all-solid-state symmetric supercapacitors with a PVA–KOH gel electrolyte, the devices achieved a high energy density of 50 Wh kg⁻¹ at a power density of 0.75 kW/kg. These findings underscore the efficacy of carbide–perovskite hybridization in creating multifunctional electrode materials for next-generation, high-performance energy storage systems.