Open AccessNature of Five-Coordinated Al in γ-Al2O3 Revealed by Ultra-High-Field Solid-State NMR
Author(s) -
Zhenchao Zhao,
Dong Xiao,
Kuizhi Chen,
Rui Wang,
Liang Liu,
Zhengmao Liu,
Ivan Hung,
Zhehong Gan,
Guangjin Hou
Publication year - 2022
Publication title -
acs central science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.893
H-Index - 76
eISSN - 2374-7951
pISSN - 2374-7943
DOI - 10.1021/acscentsci.1c01497
Subject(s) - characterization (materials science) , amorphous solid , solid state nuclear magnetic resonance , phase (matter) , materials science , surface (topology) , field (mathematics) , catalysis , high resolution , crystallography , chemical physics , nanotechnology , chemistry , nuclear magnetic resonance , physics , organic chemistry , geometry , mathematics , remote sensing , geology , pure mathematics
Five-coordinated Als (Al(V)) on the surface of aluminas play important roles when they are used as catalysts or catalyst supports. However, the comprehensive characterization and understanding of the intrinsic structural properties of the Al(V) remain a challenge, due to the very small amount in commonly used aluminas. Herein, the surface structures of γ-Al 2 O 3 and Al(V)-rich Al 2 O 3 nanosheets (Al 2 O 3 -NS) have been investigated and compared in detail by multinuclear high-field solid-state NMR. Thanks to the high resolution and sensitivity of ultra-high-field (up to 35.2 T) NMR, the arrangements of surface Als were clearly demonstrated, which are substantially different from the bulk phase in γ-Al 2 O 3 due to the structure reconstruction. It reveals for the first time that most of the commonly observed Al(V)s tend to exist as aggregated states on the surface of γ-Al 2 O 3 , like those in amorphous Al 2 O 3 -NS liable to structure reconstruction. Our new insights into surface Al(V) species may help in understanding the structure-function relationship of alumina.