Atomic Visualization\nfor Dissociative Adsorption of\nHydrogen on Co(0001)

The\nadsorption and dissociation of hydrogen on the Co(0001)\nsurface\nwere investigated by using density functional theory (DFT) calculations\nand scanning tunneling microscopy (STM) experiments. DFT calculations\nrevealed a negligible energy barrier for H<sub>2</sub> dissociation\nupon adsorption, with H atoms preferentially occupying hollow sites\n(fcc and hcp). The facile diffusion of H atoms across the surface\nwas also observed. A phase diagram for H adsorption on Co(0001) was\nconstructed, identifying the most stable phases under varying conditions.\nSTM experiments successfully visualized the atomic arrangements of\nboth the 1H-(1 × 1) and 2H-(2 × 2) phases. Precise attribution\nof detailed STM imaging features is established for the adsorption\nof H on Co(0001), confirming the theoretical predictions and providing\ndirect experimental evidence for the dissociative adsorption of hydrogen\non Co(0001).