Surface morphology evolution of cobalt nanoparticles induced by hydrogen adsorption: a theoretical study

Abstract

Determining the surface structure and morphology under working conditions is essential to obtain facet-dependent catalytic performance. However, the evolution of the morphology and exposed surfaces of nanocatalysts is sensitive to experimental conditions such as temperature and gaseous pressure, which brings about a great experimental challenge to obtain this information. Herein, ab initio thermodynamics, density functional theory and Wulff morphology were employed to investigate the surface structure and morphology evolution of HCP-Co under hydrogen-relevant conditions. From the stepwise adsorption on each facet of HCP-Co, hydrogen prefers to adsorb on threefold hollow sites. The morphology of HCP-cobalt presents a quasi-spherical shape and the main exposed surfaces of HCP-Co are (0001), (10−10), (10−11) and (10−12) under different temperatures and hydrogen partial pressures. This work provides complementary information to experimental studies for knowing the microstructures of cobalt nanocatalysts in hydrogen-involved reactions.