Interface-engineered Bi₂O₃/N-doped carbon heterostructure enabling synergistic effects for advanced energy storage

Metal oxide/carbon nanocomposites have emerged as prospective electrodes for electrochemical energy storage. In this case, revealing the synergistic mechanism of metal oxide/carbon is favorable to guide the design of nanocomposites and enhance their electrochemical performance. Thus, in this study, an interface-engineered Bi₂O₃/N-doped carbon heterostructure (Bi₂O₃@NPCF) was designed as a high-performance active site for K⁺ and Na⁺ storage. Density functional theory (DFT) calculations substantiated that the Bi₂O₃/N-doped carbon interface generates a strong built-in electric field and an optimized band structure, enhancing charge accumulation/transfer and boosting redox kinetics. The synergistic interactions between Bi₂O₃ and NPCF can simultaneously induce both rapid ion diffusion and enhanced surface charge storage, and consequently, Bi₂O₃@NPCF exhibited outstanding electrochemical behavior in both 2 M KOH and 2 M NaOH electrolyte. Furthermore, an asymmetric aqueous supercapacitor device was assembled using Bi₂O₃@NPCF and Co(OH)₂/Ag electrodes, achieving a high energy density of 128.9 μWh cm⁻² at a power density of 0.92 mW cm⁻² as well as good stability, highlighting its promising application prospects. © 2025 The Royal Society of Chemistry.