AP在氟化石墨烯表面分解机理的密度泛函理论研究

Density Functional Theory Study on the Decomposition Mechanism of Ammonium Perchlorate on the Surface of Fluorographene

为了探讨氟化石墨烯(FG)用于AP燃烧催化的可行性,采用密度泛函理论(DFT)计算方法研究了HClO_(4)和NH_(3)在FG表面的分解行为,阐述了AP在FG表面分解的反应机理;对HClO_(4)分子在FG表面分解反应的反应网络中各个基元反应的活化能和反应热进行了分析。结果表明,HClO_(4)分子的主要分解路径为HClO_(4)→ClO_(3)→HClO_(3)→ClO_(2)→HClO2→ClO-→Cl-。高氯酸分解生成氯酸根的反应为该路径的速控步骤,反应活化能为1.675 eV;HClO_(4)分子分解产生的吸附在FG表面的O^(*)原子会抑制HClO_(4)分子在FG表面的进一步分解,但这些O^(*)原子能够促进NH_(3)分子在FG表面的脱氢反应并生成OH^(*)基团;OH^(*)基团易与NH_(3)分子及其脱氢产物反应,生成H_(2)O分子,使得O原子从FG表面脱附;FG表面的F原子能够迅速与NH_(3)分子中的H原子反应,反应活化能仅为0.284 eV,这促使NH_(3)脱氢并吸附在催化剂表面,避免了因为NH_(3)吸附在AP表面而引起的阻滞期。表明FG能够有效地消除AP分解过程的阻滞期,从而提高AP的燃烧性能。

To explore the feasibility of fluorographene(FG)used as the combustion catalyst of ammonium perchlorate(AP),the first-principles calculations based on density functional theory(DFT)were employed to investigate the decomposition of HClO_(4)and NH_(3)through the catalysis of FG,and the decomposition mechanism of AP was expounded.Based on the analysis of the activation energy barriers and reaction heats of the elementary reactions among the reaction network,the main reaction channels of the decomposition of HClO_(4)on the surface of FG were proposed and determined.The results show that the main decomposition path of HClO_(4)is:HClO_(4)→ClO_(3)→HClO_(3)→ClO_(2)→HClO2→ClO-→Cl-.The rate-determining step of this reaction pathway is the decomposition to ClO_(3)from HClO_(4)with the activation energy barrier of 1.675eV.The adsorbed O^(*)atoms generated by the decomposition of HClO_(4)inhibit the further decomposition of HClO_(4)on the FG surface.Meanwhile,these O^(*)atoms promote the dehydrogenation reaction of NH_(3)on the FG surface and generate OH^(*)groups.The OH^(*)group can easily react with NH_(3)and its dehydrogenation products to generate H_(2)O molecule,causing the O atom to desorb from the FG surface.The energy barrier of the dehydrogenation reaction between NH_(3)and F atom is 0.284 eV,indicating that NH_(3)can easily decompose and adsorb on the catalyst surface instead of adsorbing on AP surface,thus inhibiting the degradation of AP.The FG catalyst can eliminate the stagnation decomposition process during the decomposition of AP,and enhance its combustion performance.