Adsorption and catalysis of Bi-doped Fe2O3 on gas products of HMX decomposition: A DFT study

Abstract To clarify the role of Bi-doped Fe2O3(0 0 1) in the decomposition process of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX), the effect of Bi-Fe2O3(0 0 1) on the gas products of HMX(NO, NO2, N2O, H2O, CH2O) was emphatically investigated using density functional theory (DFT) calculation. The adsorption configuration, energy, electronic properties and possible reactions of gas products were considered. All of these gases are adsorbed on the Fe-top site of Bi-Fe2O3 surface in molecular form, resulting in the orbital hybridization and electron transfer. NO2 and CH2O interacting with Bi are of higher adsorption energy comparing with gas adsorbed on pure Fe2O3(0 0 1). Since the reaction of NO2 with CH2O and the dissociation of NO2 play an important role in the subsequent decomposition of HMX, the effects of Bi doping on these two reactions were investigated. TS search shows that the activation energy of these two reactions are all decreased on Bi-Fe2O3 surface, which may accelerate the consumption of NO2, indicating that Bi doping can promote the reaction of NO2 and CH2O, thus accelerating the subsequent decomposition of HMX.