Effects of the coordination number on H_2O dissociation reaction on the surface of Zr_(5n)O_(10n) (n=4-9) nanoparticles: A DFT approach

摘要

The behaviors of H2O adsorption and dissociation on the Zr5nO10n (n = 4-9) nanoparticles are investigated by density functional theory calculations. We find that the coordination number of Zr plays a significant role in H2O and OH adsorption. Our results demonstrate that the adsorption of H2O and OH on the Zr-CN5 (Zr atom with five coordination number) site is stronger than that on the ZI(CN6)site (Zr atom with six coordination number), while hydrogen is easily absorbed on the 00.12 (the O atom with two coordination number) site. Particularly, the coordination number of Zr also influences the H2O dissociation reaction. Through analyzing the reaction pathways of H2O dissociation on Zr-CN5 and Zr-CN6 site of the Zr5nO10n. (n = 4-9) nanoparticles, we explore that the H2O molecules can be easily decomposed on Zr-CN5 and Zr-CN6 sites. The largest energy barrier of H2O dissociation is 0.247 eV, which is found on the Zr-CN6 of Zr20O40 nanoparticles. For the Zr-CN6 of Zr20O40 nanoparticles, this energy barrier is even smaller. We found that the adsorption energy and H2O dissociation are sensitive to the coordination number of nanoparticles. Besides, the reaction rate constant of H2O dissociation on Zr-CN5 site of all nanoparticles are larger than that on Zr-CN(6) site. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.