The catalytic oxidation of CO on Cu-embedded graphene is investigated by DFT. The reaction proceeds via a two-step mechanism of CO + O2 → OOCO → CO2 + O and CO + O → CO2. The energy barriers of the former are 0.25 and 0.54 eV, respectively, while the latter is a process with energetic drop. The high activity of Cu-embedded graphene may be attributed to the electronic resonance among electronic states of CO, O2, and the Cu atom, particularly among Cu-3d, CO-2π*, and O2-2π* orbitals. This good catalytic activity opens a new avenue to fabricate carbon-based catalysts for CO oxidation with lower cost and higher activity.

Inside a liquid solution, oriented attachment (OA) is now recognized to be as important a pathway to crystal growth as other, more conventional growth mechanisms. However, the driving force that controls the occurrence of OA is still poorly understood. Here, using in-situ liquid cell transmission electron microscopy, we demonstrate the ligand-controlled OA of citrate-stabilized gold nanoparticles at atomic resolution. Our data reveal that particle pairs rotate randomly at a separation distance greater than twice the layer thickness of adsorbed ligands. In contrast, when the particles get closer, their ligands overlap and guide the rotation into a directional mode until they share a common {111} orientation, when a sudden contact occurs accompanied by the simultaneous expulsion of the ligands on this surface. First-principle calculations confirm that the lower ligand binding energy on {111} surfaces is the intrinsic reason for the preferential attachment at this facet, rather than on other low-index facets.

The intrinsic activity of in-plane chalcogen atoms plays a significant role in the catalytic performance of transition metal dichalcogenides (TMDs). A rational modulation of the local configurations is essential to activating the in-plane chalcogen atoms but restricted by the high energy barrier to break the in-plane TM-X (X = chalcogen) bonds. Here, we theoretically design and experimentally realize the tuning of local configurations. The electron transfer capacity of local configurations is used to screen suitable TMDs materials for hydrogen evolution reaction (HER). Among various configurations, the triangular-shape cobalt atom cluster with a central sulfur vacancy (3Co Mo-V S) renders the distinct electrocatalytic performance of MoS 2 with much reduced overpotential and Tafel slope. The present study sheds light on deeper understanding of atomic-scale local configuration in TMDs and a methodology to boost the intrinsic activity of chalcogen atoms.