Graphitic carbon nitride (g-C3N4) as a metal-free catalyst for thermal decomposition of ammonium perchlorate

Abstract

Development of metal-free and environmentally friendly catalysts is of great significance for thermal decomposition of ammonium perchlorate (AP). In the present study, graphitic carbon nitride (g-C₃N₄) has been demonstrated to possess intrinsic catalytic activity for thermal decomposition of AP. Adding 10 wt% g-C₃N₄ to AP decreases the decomposition temperature by 70 °C and the activation energy (E_a) by 119.8 kJ mol⁻¹. Moreover, the apparent decomposition heat of AP in the presence of 10 wt% g-C₃N₄ reaches up to 1362.6 J g⁻¹, which is much higher than that of the pure AP (574.2 J g⁻¹). Furthermore, a possible catalytic mechanism for the thermal decomposition of AP with g-C₃N₄ has been proposed. The unique surface structure of g-C₃N₄ consisting of triazine units connected by planar amino groups can be favourable for the adsorption and diffusion of perchloric acid via Lewis acid–base interactions, which decreases the reaction activation energy of AP and facilitates the formation of superoxide radical anions (˙O₂⁻) and holes (h⁺), leading to the oxidation reaction of ammonia more completely in the catalytic decomposition of AP.