The crucial role of water clusters (H2O)n (n=0 –5) on the catalytic oxidation of AsH3: An accurate theoretical investigation

In this study, the role of explicit water molecules on the AsH3 catalytic oxidation AsH3 +O2 +nH2O (n=0–5) was investigated using Density Functional Theory (DFT) method at B3LYP/6-311+G (d,p) level. The addition of (H2O)n (n=1–5) shows promoting catalytic effect on the oxidation process by reducing the reaction barrier energy of 3.27–10.70kcal/mol compared to the reaction without water molecule (16.44kcal/mol). One explicit H2O addition shows best catalytic effect on the oxidation process. The decreasing order of reaction energy barrier is 0H2O>(H2O)5 >(H2O)4 >(H2O)2 >(H2O)3 >H2O. Natural bond orbital (NBO) analysis was also conducted to confirm the bond-breaking and bond-making processes. Furthermore, reaction rate constants (kTS) of six catalytic oxidation reactions from 293K to 433K have been calculated to determine the catalytic role of water clusters. The values of kTS increase progressively with increasing temperature in the six reaction paths (n=0–5). Three water addition is most kinetically favourable among the six reactions. Graphical abstract

Source: Computational and Theoretical Chemistry - June 15, 2017 Category: Chemistry Source Type: research