Stabilization of Colloidal Ti, Zr, and Hf Oxide Nanocrystals by Protonated Tri-n-octylphosphine Oxide (TOPO) and Its Decomposition Products

被引：54

作者：

De Keukeleere, Katrien ^{[1
]}

Coucke, Sofie ^{[1
]}

De Canck, Els ^{[1
]}

Van Der Voort, Pascal ^{[1
]}

Delpech, Fabien ^{[2
]}

Coppel, Yannick ^{[3
]}

Hens, Zeger ^{[1
]}

Van Driessche, Isabel ^{[1
]}

Owen, Jonathan S. ^{[4
]}

De Roo, Jonathan ^{[1
,4
]}

机构：

[1] Univ Ghent, Dept Chem, B-9000 Ghent, Belgium

[2] Univ Toulouse, CNRS, LPCNO, INSA,UPS, F-31077 Toulouse 9, France

[3] Univ Toulouse, CNRS, UPR 8241, Lab Chim Coordinat, F-31077 Toulouse 9, France

[4] Columbia Univ, Dept Chem, New York, NY 10027 USA

来源：

CHEMISTRY OF MATERIALS | 2017年 / 29卷 / 23期

基金：

欧盟地平线“2020”;

关键词：

SOL-GEL SYNTHESIS; SURFACE-CHEMISTRY; LIGAND-EXCHANGE; NONAQUEOUS SYNTHESIS; BUILDING-MATERIALS; SCALE SYNTHESIS; ACID PROPERTIES; METAL; NANOPARTICLES; NMR;

D O I：

10.1021/acs.chemmater.7b04580

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

Although TiO2, ZrO2, and HfO2 nanocrystals are often synthesized in tri-n-octylphosphine oxide (TOPO), it is unclear whether TOPO also serves as ligand. Using liquid and solid state H-1 and P-31 nuclear magnetic resonance spectroscopy and X-ray fluorescence spectroscopy, we show that the nanocrystal surface is capped by several derivatives of TOPO. In the P-31 NMR spectrum, di-n-octylphosphinate (delta = 57 ppm) and P,P'-(di-n-octyl) pyrophosphonate (delta = 20 ppm) are found coordinated to the nanocrystal. In addition, hydrogen chloride associates with the metal oxide nanocrystal surface and protonates TOPO. The resulting hydroxyl-tri-n-octylphosphonium, [HO-PR3](+), is tightly associated with the nanocrystal surface (delta(P-31) = 73 ppm) due to electrostatic interactions and hydrogen bonding. To simplify the complex surface composition, we exchange the original surface species for carboxylate or phosphonate ligands. The protonation of TOPO is an unexpected example of lyophilic ion pairing between an acidic metal oxide nanocrystal and a weakly basic ligand molecule that is formed in nonpolar solution. Our results contrast with the classically envisaged L-type binding motif of TOPO to surface metal ions. The generality of this stabilization mode and its relevance to catalysis is discussed.

引用

页码：10233 / 10242

页数：10

共 83 条

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