Abstract
Single-atom catalysts not only maximize metal atom efficiency, they also display properties that are considerably different to their more conventional nanoparticle equivalents, making them a promising family of materials to investigate. Herein we developed a general host–guest strategy to fabricate various metal single-atom catalysts on nitrogen-doped carbon (M1/CN, M = Pt, Ir, Pd, Ru, Mo, Ga, Cu, Ni, Mn). The iridium variant Ir1/CN electrocatalyses the formic acid oxidation reaction with a mass activity of 12.9 \({{{\rm{A}}\,{\rm{mg}}^{-1}_{{\rm{Ir}}}}}\) whereas an Ir/C nanoparticle catalyst is almost inert (~4.8 × 10−3 \({{{\rm{A}}\,{\rm{mg}}^{-1}_{{\rm{Ir}}}}}\)). The activity of Ir1/CN is also 16 and 19 times greater than those of Pd/C and Pt/C, respectively. Furthermore, Ir1/CN displays high tolerance to CO poisoning. First-principle density functional theory reveals that the properties of Ir1/CN stem from the spatial isolation of iridium sites and from the modified electronic structure of iridium with respect to a conventional nanoparticle catalyst.
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Acknowledgements
The authors thank M.F. Li (University of California at Los Angeles) who provided insight and expertise that greatly assisted the research. This work was supported by the National Key R&D Program of China (grant no. 2018YFA0702003), the National Natural Science Foundation of China (grant nos. 21890383, 21671117, 21871159) and the Beijing Municipal Science & Technology Commission (grant no. Z191100007219003).
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D.W. and Y.L. conceived the idea, designed the study, planned synthesis and wrote the paper. Z.L., Y.C. and S.J. performed most of the reactions, collected and analysed the data, and wrote the paper. L.G., Y.G. and J. Luo performed electron-microscopy characterizations. W.C., Y.W., L.Z., J.D., T.Y., W.L. and S. W. carried out the X-ray absorption fine structure characterizations. Y.T., J. Li, C.P. and P.H. finished the DFT calculations. A.L. performed the in situ ETEM characterizations. J. Zhao helped to synthesize and characterize the iridium homogeneous compound. W.Z., Z.Z. and W.X. helped with electrochemical measurements and the analysis of electrocatalytic results. W.-C.C helped with the analysis of electron-microscopy characterizations. C.-T.H., Y.X., Q.L., M.Z., Z.C., N.F., X.G., J.W. and J. Zhang performed some of the synthesis experiments. Y.W., C.C., Q.P., X.D., Y.H. and X.-M.C. provided valuable suggestions and helped revise the manuscript.
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Li, Z., Chen, Y., Ji, S. et al. Iridium single-atom catalyst on nitrogen-doped carbon for formic acid oxidation synthesized using a general host–guest strategy. Nat. Chem. 12, 764–772 (2020). https://doi.org/10.1038/s41557-020-0473-9
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DOI: https://doi.org/10.1038/s41557-020-0473-9
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