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Title: Enhancing catalytic epoxide ring-opening selectivity using surface-modified Ti 3 C 2 T x MXenes
Abstract

MXenes are a new family of two-dimensional carbides and/or nitrides. Their 2D surfaces are typically terminated by O, OH and/or F atoms. Here we show that Ti3C2Tx—the most studied compound of the MXene family—is a good acid catalyst, thanks to the surface acid functionalities. We demonstrate this by applying Ti3C2Txin the epoxide ring-opening reaction of styrene oxide (SO) and its isomerization in the liquid phase. Modifying the MXene surface changes the catalytic activity and selectivity. By oxidizing the surface, we succeeded in controlling the type and number of acid sites and thereby improving the yield of the mono-alkylated product to >80%. Characterisation studies show that a thin oxide layer, which forms directly on the Ti3C2Txsurface, is essential for catalysing the SO ring-opening. We hypothesize that two kinds of acid sites are responsible for this catalysis: In the MXene, strong acid sites (both Lewis and Brønsted) catalyse both the ring-opening and the isomerization reactions, while in the Mxene–TiO2composite weaker acid sites catalyse only the ring-opening reaction, increasing the selectivity to the mono-alkylated product.
Authors:
; ; ; ; ; ;
Award ID(s):
1740795
Publication Date:
NSF-PAR ID:
10362624
Journal Name:
2D Materials
Volume:
8
Issue:
3
Page Range or eLocation-ID:
Article No. 035003
ISSN:
2053-1583
Publisher:
IOP Publishing
Sponsoring Org:
National Science Foundation
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