Abstract
We have performed transition state calculations using dispersion-corrected density-functional theory on atomic Au- and atomic Pd- negative ion catalysis of H2O, HDO, and D2O conversion to H2O2, HDO2, and D2O2, respectively. The atomic Au- negative ion is found to be an excellent catalyst; however, the atomic Pd- negative ion has a higher catalytic effect on the formation of peroxide from light, intermediate, and heavy water. These atomic negative ion catalysts speed up the reactions by lowering the activation energy, with the atomic Pd- negative ion accomplishing the catalysis by a factor of about 3 times faster than that by the atomic Au- negative ion. The fundamental mechanism involves anionic molecular complex formation in the transition state, with the atomic Au- and atomic Pd- negative ions breaking up the hydrogen bond strength in the water molecules, permitting the formation of the peroxides in the presence of O-2 usually provided by the support. Our theoretical results provide further insight into the mechanism of atomic Au- and atomic Pd- negative ion catalysis consistent with the recent experimental observations and theoretical calculation.