title: Atomic level control over surface species via a molecular precursor approach: isolated Cu(I) sites and Cu nanoparticles supported on mesoporous silica.
abstract: A nonaqueous molecular precursor grafting approach was employed for the generation of well-defined surface structures featuring Cu on a mesoporous silica support. X-ray absorption measurements (XANES and EXAFS) were used to determine that [CuOSi(OtBu)3]4 provided 100% isolated Cu(I) sites upon grafting (without thermal treatment), whereas [CuOtBu]4 gave isolated species with most of the original Cu-O-Cu linkages intact, but in a more relaxed straight chain form. Upon heating under inert conditions, the vast majority of Cu in the materials from [CuOSi(OtBu)3]4 remained as isolated Cu(I) sites (up to 88% isolation), with significant stabilization provided from the -OSi(OtBu)3 ligands. In stark contrast, approximately 100% of the Cu in the materials generated from [CuOtBu]4 was readily reduced upon heating, forming isolated Cu metal particles with an average diameter of 0.7 nm.
authors.affiliation: Departments of Chemistry and Chemical Engineering, University of California-Berkeley, Berkeley, CA 94720, USA.
authors.forename: Kyle L
authors.initials: KL
authors.lastname: Fujdala
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Drake
authors.forename: Alexis T
authors.initials: AT
authors.lastname: Bell
authors.forename: T Don
authors.initials: TD
authors.lastname: Tilley