Thermal protocol-driven oxidative etching of ZrC Embedded carbon nanofibers to unlock ZrOxCy nanodomains for selective H2O2 production

Abstract

Hydrogen peroxide (H₂O₂) production via electrochemical two-electron oxygen reduction reaction (2e⁻ ORR) provides a sustainable alternative to conventional synthesis methods. In this study, we develop a protocol-programmed oxidative-etching strategy integrated into an electrospun CNF platform, in which a stepwise air-to-Ar thermal sequence is deliberately designed to reconstruct and expose the near-surface region of confined ZrC into surface-accessible ZrO_xC_y nanodomains with Zr–O–C interfacial coordination, rather than post-oxidizing bulk ZrC. Controlled thermal protocol for oxidative etching effectively modulated the surface chemistry, mesoporosity, and active site exposure of Zr-based nanodomains at 500 °C. Comprehensive structural and electrochemical analyses demonstrated that the optimized ZrO_xC_y@CNF catalyst exhibited catalytic activity and selectivity for 2e⁻ ORR based H₂O₂ generation, achieving approximately 85% selectivity and a mass activity of 8.52 A g⁻¹ at 0.65 V versus RHE. The synergistic combination of exposed ZrO_xC_y interfacial sites within oxygen vacancies and the electrically conductive one-dimensional CNF backbone facilitated efficient 2e⁻ ORR, enabling low overpotentials and high current densities. These results demonstrate the feasibility of protocol-programmed oxidative etching for tuning selectivity in CNF-supported Zr-based catalysts.