Combustion synthesis of carbon hollow nanocubes: DFT modelling and electrochemical performance analysis

A straightforward, energy-efficient, and scalable combustion synthesis (CS) method for synthesizing graphitized hollow carbon nanocube (G-HCNC) through the magnesiothermic reduction of CaCO₃ is developed. By controlling the synthesis temperature, we effectively modulated the size of self-templated MgO nanocubes, thereby influencing the size and surface area of the hollow carbon nanocubes formed on the MgO surface. In our ongoing experiments, the edge size of G-HCNC ranged from 100 to 500 nm, with a 15–50 nm thickness. Remarkably, a specific surface area as high as 977.5 m²/g near the combustion boundary at k = 8 is achieved. When tested as support for Mo₂C electrocatalyst, G-HCNC demonstrated low overpotential (120 mV) in the hydrogen evaluation reaction (HER). Moreover, when loaded with 10 % Ag, G-HCNC exhibits an excellent specific capacity (428.9 F/g) in a KOH electrolyte. This development holds promise for generating various complex structures enveloped by graphitized carbon layers for energy storage applications.