Electrostatic Stabilization of Single-Atom Catalysts by Ionic Liquids

In single-atom catalysts (SACs), the isolated metal atoms on solid support are often charged. Taking advantage of this common feature, we establish ionic liquid-stabilized single-atom catalysts (ILSSACs) employing electrostatic interaction as a general stabilization strategy. While Pt nanoparticles were formed on hydroxyapatite after reaction when unprotected, Pt remained atomically dispersed on ionic liquid-stabilized samples. Density functional theory calculations reveal that the activation energy for the transformation of two isolated Pt atoms to a Pt dimer increases remarkably from 0.11 to 0.72 eV with the protection of [Bmim][BF4]. The presence of ILs also tunes the electronic state of Pt1, inducing an order-of-magnitude hydrogenation activity increase. The simple stabilization strategy is easily extended to SACs comprising various metal atom-support combinations. For instance, ILs significantly improved the stability and selectivity of a Pd1 catalyst for the hydrogenation of acetylene, thus outperforming unprotected SACs.

Citation

Ding, S., Guo, Y., Hülsey, M. J., Zhang, B., Asakura, H., Liu, L., … Yan, N. (2019). Electrostatic Stabilization of Single-Atom Catalysts by Ionic Liquids. Chem. doi:10.1016/j.chempr.2019.10.007

Sponsors

This work has been supported by the National University of Singapore Flagship Green Energy Program (#R-279-000-553-646 and R-279-000-553-731). The computations were partly performed at the Research Center for Computational Science, Okazaki, Japan, and partly supported by Grant-in-Aid for Young Scientists (B) (17K1442907) in Japan. N.Y. conceived and supervised the project. S.D. carried out the catalyst synthesis, catalytic performance test, stability evaluation, and kinetic study and conducted some characterizations. S.D. N.Y. M.H. and B.Z. analyzed the data. L.L. and Y.H. carried out the HAADF-STEM characterizations. H.A. carried out the XAS measurements and analysis. M.G. and J.H. conducted the DFT calculation. S.D. and N.Y. wrote the paper. Y.G. B.Q. and T.Z. prepared the Pd/HAP catalyst, performed the HADDF-STEM and acetylene hydrogenation measurement, and wrote the Pd/HAP section. All authors contributed to project discussions and modified the manuscript. The authors declare no competing interests.