Scalable Synthesis of Triple‐Core–Shell Nanostructures of TiO₂@MnO₂@C for High Performance Supercapacitors Using Structure‐Guided Combustion Waves

Core–shell nanostructures of metal oxides and carbon‐based materials have emerged as outstanding electrode materials for supercapacitors and batteries. However, their synthesis requires complex procedures that incur high costs and long processing times. Herein, a new route is proposed for synthesizing triple‐core–shell nanoparticles of TiO 2 @MnO 2 @C using structure‐guided combustion waves (SGCWs), which originate from incomplete combustion inside chemical‐fuel‐wrapped nanostructures, and their application in supercapacitor electrodes. SGCWs transform TiO 2 to TiO 2 @C and TiO 2 @MnO 2 to TiO 2 @MnO 2 @C via the incompletely combusted carbonaceous fuels under an open‐air atmosphere, in seconds. The synthesized carbon layers act as templates for MnO 2 shells in TiO 2 @C and organic shells of TiO 2 @MnO 2 @C. The TiO 2 @MnO 2 @C‐based electrodes exhibit a greater specific capacitance (488 F g −1 at 5 mV s −1 ) and capacitance retention (97.4% after 10 000 cycles at 1.0 V s −1 ), while the absence of MnO 2 and carbon shells reveals a severe degradation in the specific capacitance and capacitance retention. Because the core‐TiO 2 nanoparticles and carbon shell prevent the deformation of the inner and outer sides of the MnO 2 shell, the nanostructures of the TiO 2 @MnO 2 @C are preserved despite the long‐term cycling, giving the superior performance. This SGCW‐driven fabrication enables the scalable synthesis of multiple‐core–shell structures applicable to diverse electrochemical applications.