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General synthesis of single-atom catalysts with high metal loading using graphene quantum dots

Abstract

Transition-metal single-atom catalysts present extraordinary activity per metal atomic site, but suffer from low metal-atom densities (typically less than 5 wt% or 1 at.%), which limits their overall catalytic performance. Here we report a general method for the synthesis of single-atom catalysts with high transition-metal-atom loadings of up to 40 wt% or 3.8 at.%, representing several-fold improvements compared to benchmarks in the literature. Graphene quantum dots, later interweaved into a carbon matrix, were used as a support, providing numerous anchoring sites and thus facilitating the generation of high densities of transition-metal atoms with sufficient spacing between the metal atoms to avoid aggregation. A significant increase in activity in electrochemical CO2 reduction (used as a representative reaction) was demonstrated on a Ni single-atom catalyst with increased Ni loading.

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Fig. 1: Schematic illustration of the synthesis process of single-atom catalysts using different strategies.
Fig. 2: Synthesis and characterization of atomically dispersed iridium catalyst with iridium content of approximately 41 wt% and 3.84 at.%.
Fig. 3: Characterization of atomically dispersed iridium catalyst with iridium content of ~41 wt%.
Fig. 4: Generality of the GQD-assisted strategy for synthesizing atomically dispersed TM catalysts with high metal content.

Data availability

The authors declare that all of the data supporting the findings of this study are available within the paper and the Supplementary Information, and also from the corresponding authors upon reasonable request. Source data are provided with this paper.

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Acknowledgements

This work was supported by Rice University and the Welch Foundation Research Grant C-2051-20200401. H.W. is a CIFAR Azrieli Global Scholar in the Bio-inspired Solar Energy Program. C.X. acknowledges support from a J. Evans Attwell-Welch Postdoctoral Fellowship. C.X. acknowledges the University of Electronic Science and Technology of China for startup funding (A1098531023601264). This work was performed in part at the Shared Equipment Authority at Rice University. H.N.A. acknowledges support from King Abdullah University of Science and Technology. XAS and PDF measurements were conducted at the Canadian Light Source, which is supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), National Research Council Canada (NRC) and University of Saskatchewan. Electron microscopy was conducted at the Center for Nanophase Materials Sciences, which is a U.S. Department of Energy Office of Science User Facility.

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Contributions

The project was conceptualized by C.X. and H.W. and supervised by H.W. and Y.H. Catalysts were synthesized by C.X. with the help of Y.Q.; C.X., Y.Q. and P.Z. conducted the catalytic tests and the related data processing. Materials characterization and analysis were performed by C.X. with the help of P.Z., Y.X., X.Z., Z.W., D.Z., P.L., D.A.C. and J.Y.K. The XAS test and analysis was performed by M.S., E.H., P.C. and Y.H. PDF was performed by G.K.; H.N.A provided suggestions for this study. C.X. and H.W. wrote the manuscript with input from all the authors.

Corresponding authors

Correspondence to Chuan Xia or Yongfeng Hu or Haotian Wang.

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The authors declare no competing interests.

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Peer review information Nature Chemistry thanks Aiqin Wang, Yuen Wu and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–27, Table 1 and references.

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Source Data Fig. 2

Statistical source data.

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Xia, C., Qiu, Y., Xia, Y. et al. General synthesis of single-atom catalysts with high metal loading using graphene quantum dots. Nat. Chem. (2021). https://doi.org/10.1038/s41557-021-00734-x

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