A facile method for the synthesis of a C@MoO₂ hollow yolk-shell structure and its electrochemical properties as a faradaic electrode

Transition-metal oxide hollow yolk-shell micro/nanostructures combined with a conducting substance have gained significant attention as efficient electrode materials for electrochemical energy storage applications due to their large surface area, internal void space, and structural stability. Herein, we report a facile aqueous solution-based soft template method using sucrose-CTAB for the synthesis of a hollow yolk-shell structure of carbon-incorporated MoO₂ (C@MoO₂) with a diameter of 0.9-1.1 μm, wall thickness of 100 nm, inner yolk size of 400-450 nm, and BET surface area of 40 m² g^-1. During the synthesis process, sucrose plays a dual role, both as a template and a carbon source. The electrochemical charge storage mechanism follows a battery-type behaviour when tested as a faradaic electrode in 3.0 M KOH electrolyte. C@MoO₂ exhibits a high specific capacity of 188 C g^-1 at the current density of 0.5 A g^-1, good rate performance (50.6 C g^-1 at 10 A g^-1), and 78% retention of capacity after 5000 cycles at 5 A g^-1. The obtained performance is superior to those obtained for pure MoO₂ hollow spheres (137.1 C g^-1 at 0.5 A g^-1) as well as previously reported MoO₂ and MoO₃, indicating the potential applicability of the as-synthesised yolk-shell C@MoO₂.