Labeling and Probing the Silica Surface Using Mechanochemistry and 17O NMR Spectroscopy

Chia‐hsin Chen (1) , Frederic Mentink‐vigier (2) , Julien Trébosc (3) , Ieva Goldberga (1) , Philippe Gaveau (1) , Emilie Thomassot (4) , Dinu Iuga (5) , Mark Smith (6) , Kuizhi Chen (2) , Zhehong Gan (2) , Nicolas Fabregue (1) , Thomas-Xavier Métro (7) , Bruno Alonso (1, 8) , Danielle Laurencin (1)

1 ICGM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
2 NHMFL - National High Magnetic Field Laboratory
3 IMEC - Institut Michel Eugène Chevreul - FR 2638
4 CRPG - Centre de Recherches Pétrographiques et Géochimiques
5 University of Warwick [Coventry]
6 University of Southampton
7 IBMM - Institut des Biomolécules Max Mousseron [Pôle Chimie Balard]
8 ENSCM - Ecole Nationale Supérieure de Chimie de Montpellier

In recent years, there has been increasing interest in developing cost-efficient, fast, and user-friendly O-17 enrichment protocols to help to understand the structure and reactivity of materials by using O-17 NMR spectroscopy. Here, we show for the first time how ball milling (BM) can be used to selectively and efficiently enrich the surface of fumed silica, which is widely used at industrial scale. Short milling times (up to 15 min) allowed modulation of the enrichment level (up to ca. 5 %) without significantly changing the nature of the material. High-precision O-17 compositions were measured at different milling times by using large-geometry secondary-ion mass spectrometry (LG-SIMS). High-resolution O-17 NMR analyses (including at 35.2 T) allowed clear identification of the signals from siloxane (Si-O-Si) and silanols (Si-OH), while DNP analyses, performed by using direct O-17 polarization and indirect O-17{H-1} CP excitation, agreed with selective labeling of the surface. Information on the distribution of Si-OH environments at the surface was obtained from 2D H-1-O-17 D-HMQC correlations. Finally, the surface-labeled silica was reacted with titania and using O-17 DNP, their common interface was probed and Si-O-Ti bonds identified.

Mots clés: mechanochemistry; O-17; silica; solid state NMR spectroscopy; surface chemistry

Domaines: Chimie inorganique; Chimie analytique; Matériaux

Chia‐hsin Chen, Frederic Mentink‐vigier, Julien Trébosc, Ieva Goldberga, Philippe Gaveau, et al.. Labeling and Probing the Silica Surface Using Mechanochemistry and 17O NMR Spectroscopy. Chemistry - A European Journal, 2021, 27 (49), pp.12574-12588. ⟨10.1002/chem.202101421⟩. ⟨hal-03322209⟩