Synergistic multi-functional N-doped carbon Nanocage@CNT/ZnMn₂O₄/Ti₃C₂ MXene: Powering battery, supercapacitor, and catalyzing hydrogen evolution

This study presents a novel approach to enhance the electrochemical capabilities of 3D pyrolytic carbon for energy applications. Using a chemical blowing technique, highly conductive carbon nanotubes (CNTs) are embedded within a 3D N-doped carbon nanocage (NCN). This integration involves an additional carbon source during Ni(NO₃)₂ induced polymer blowing, leveraging the dual role of Ni(NO₃)₂ in polymer expansion and catalyzing CNT growth. Our research merges ZnMnO₄/Ti₃C₂ with high-capacity N-Doped Carbon Nanocage@CNT (NCN/CNT@ZnMnO₄/Ti₃C₂) to amplify electrochemical performance. The NCN/CNT@ZnMnO₄/Ti₃C₂ showed specific capacitance of 1843 Cg^-1 at 1.0 Ag^-1, attributed to augmented electrical conductivity and charge storage characteristics. The supercapattery configuration maintains a specific capacitance of 195 Cg^-1 at 1.0 Ag^-1, cyclic stability of 95% over 18,000 cycles, and a power density of 1145 W-kg⁻¹ at an energy density of 67 Wh-kg⁻¹. In HER applications, NCN/CNT@ZnMnO₄/Ti₃C₂ demonstrates a lower Tafel slope of 56.41 mV-dec⁻¹, signifying a significant advance in high-performance supercapacitors.