title: Branch number matters: Promoting catalytic reduction of 4-nitrophenol over gold nanostars by raising the number of branches and coating with mesoporous SiO2.
abstract: In this study, we demonstrate for the first time that highly branched gold nanostars (AuNSs) and silica-coated AuNSs (AuNSs@mSiO2) could potentially serve as efficient hydrogenation catalysts. The catalytic activity could be promoted by raising the number of tipped-branches of AuNSs, which reveals that the tips play an important role as active sites. The fabricated sharply-pointed AuNSs benefit the electron transfer from BH4 anions to 4-nitrophenol. Coating AuNSs with mesoporous silica (AuNSs@mSiO2) further enhanced the reduction rate and recyclability, and also contributed to reducing the induction period. The AuNSs@mSiO2 (50-100nm in diameter) are large enough to be catalytically inactive, but they consist of sharply-pointed tips with the radius of 2.6-3.6nm, which are rich in coordinately unsaturated sites similar to those of nanoparticles and clusters. Such features in structure and activity would also extend their application range in heterogeneous catalysis.
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
authors.forename: Pancras
authors.initials: P
authors.lastname: Ndokoye
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
authors.forename: Qidong
authors.initials: Q
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China; Department of Chemical Engineering, Curtin University, GPO Box U1987, Perth, Western Australia 6845, Australia. Electronic address: xyli@dlut.edu.cn.
authors.forename: Xinyong
authors.initials: X
authors.lastname: Li
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Li
authors.affiliation: Department of Chemical Engineering, Curtin University, GPO Box U1987, Perth, Western Australia 6845, Australia.
authors.forename: Moses O
authors.initials: MO
authors.lastname: Tade
authors.affiliation: Department of Chemical Engineering, Curtin University, GPO Box U1987, Perth, Western Australia 6845, Australia.
authors.forename: Shaobin
authors.initials: S
authors.lastname: Wang
keywords: Catalytic reduction; Gold nanomaterials; Hydrogenation catalyst; Mesoporous silica