Two-dimensional (2D) transition metal nanosheets are promising catalysts because of the enhanced exposure of the active species compared to their 3D counterparts. Here, we report a simple, scalable, and reproducible strategy to prepare 2D phosphate nanosheets by forming a layered structure in situ from phytic acid (PTA) and transition metal precursors. Controlled combustion of the organic groups of PTA results in interlayer carbon, which keeps the layers apart during the formation of phosphate, and the removal of this carbon results in ultrathin nanosheets with controllable layers. Applying this concept to vanadyl phosphate synthesis, we show that the method yields 2D ultrathin nanosheets of the orthorhombic β-form, exposing abundant V4+/V5+ redox sites and oxygen vacancies. We demonstrate the high catalytic activity of this material in the vapor-phase aerobic oxidation of ethyl lactate to ethyl pyruvate. Importantly, these β-VOPO4 compounds do not get hydrated, thereby reducing the competing hydrolysis reaction by water byproducts. The result has superior selectivity to ethyl pyruvate compared to analogous vanadyl phosphates. The catalysts are highly stable, maintaining a steady-state conversion of ∼90% (with >80% selectivity) for at least 80 h on stream. This "self-exfoliated" synthesis protocol opens opportunities for preparing structurally diverse metal phosphates for catalysis and other applications.
|Original language||English (US)|
|Number of pages||10|
|State||Published - Feb 19 2020|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: W.Z. thanks the China Scholarship Council (201506140058) for a PhD fellowship. P.O. thanks the Spanish Ministry of Economy and Competitiveness (MINECO) (Project CTM2015-63864-R) and the European Union (FEDER) for funding. P.O. also thanks the access and technical assistance from the Scientific-Technical Services of the University of Oviedo. This work is part of the Research Priority Area
Sustainable Chemistry of the University of Amsterdam, http://suschem.uva.nl.