摘要
An in teg rated approach combi ning den sity functional theory(DFT)calculati ons and atomic resol utio n sea nning tun neling microscopy(STM)is used to study well-defined iron-doped cobalt oxide nanoislands supported on Au(111).The focus is on the structure and distribution of Fe dopants within these nanoislands of CoO as a function of Fe to Co ratio.The DFT and STM results agree strongly and complement each other to allow for a more complete un dersta nding of the dopa nt structure trends on the nano scale.Using Fe as a marker,we first find that the stacki ng seque nee of the moire structure of the host cobalt oxide nano islands can be ide ntified un ambiguously through a combinati on of DFT and STM.Using the distinct con trast of the embedded Fe dopa nt atoms as observed with atom-resolved STM,we find correlatio ns betwee n Fe dopa nt positi on and the CoO/Au(111)moire patter n at varyi ng Fe dopa nt den sities.Formatio n of Fe-dopa nt clusters within the nano islands is investigated in detail through DFT and found to agree with the dopant patter ns observed in STM.We find that the structural effects of Fe dopants throughout the nanoislands with the basal planes and the two types of edges—the oxygen and metal edges—have different nature.Both DFT calculations and STM images show a strong preferenee for Fe dopants to be located directly on or near the oxygen edge of the nanoislands as opposed to being directly on or n ear the metal edge.Take n together,our results illustrate that Fe dopa nt incorporati on and distributi on within CoO nanoislands are highly an isotropic and gover ned by both the moire structure of the basal planes as well as nano-size effects present at the under-coordinated edges of different local geometry and chemistries.
基金
A.V.acknowledges the Canadian Institute for Advanced Research(CIFAR)for support through the Bio-inspired Solar Energy Program.J.V.L.and J.R.-F.acknowledge the VILLUM foundation.Z.Z.S.would like to acknowledge financial support from the China Scholarship Council(CSC).L.Z.,T.T.,and A.V.would like to acknowledge the use of the computer time allocation at the National Energy Research Scientific Computing Center(NERSC),a DOE Office of Science User Facility supported by the Office of Science of the U.S.Department of Energy under Contract No.DE-AC02-05CH11231
the Extreme Science and Engineering Discovery Environment(XSEDE)supported through National Science Foundation Energy under Award Number CHE160084.
