Metal-support frontier orbital interactions in single-atom catalysis

Single-atom catalysts (SACs), with their structurally simplified active sites, provide a unique platform for probing catalytic mechanisms at the atomic level. The performance of SACs—both activity and stability—is fundamentally governed by synergistic frontier orbital interactions at the metal–adsorbate and metal–support interfaces. Yet, a quantitative atomic-scale understanding of how these interactions determine catalytic performance remains elusive. Here, we show that the lowest unoccupied molecular orbital (LUMO) positions of pristine semiconducting supports, measured via Mott–Schottky analysis across 14 distinct materials, scale approximately linearly with the hydrogenation activity of supported palladium (Pd₁) atoms. Strikingly, downsizing the support to a few nanometers elevates its LUMO position, leading to record-high activity and outstanding stability in acetylene semihydrogenation. Theoretical calculations reveal that this LUMO elevation reduces the energy gap with the highest occupied molecular orbital (HOMO) of the Pd₁ atoms, which reinforces Pd₁–support orbital hybridization for enhanced stability; in turn, it sequentially tunes the LUMO of the anchored Pd₁ to amplify Pd₁–adsorbate interactions for improved activity. These findings are consistent with frontier molecular orbital (FMO) theory and establish the LUMO position of semiconducting supports as a general descriptor for the rational design of metal–support pairs with predictable hydrogenation performance.

This work was supported by the National Key R&D Program of China (2021YFA1502802, 2018YFA0208603).

1. B. Qiao, A. Wang, X. Yang, L.F. Allard, Z. Jiang, Y. Cui, J. Liu, J. Li, and T. Zhang, Single-atom catalysis of CO oxidation using Pt₁/FeO_x, Nat. Chem. 3, 634 (2011). 
2. P. Liu, Y. Zhao, R. Qin, S. Mo, G. Chen, L. Gu, D.M. Chevrier, P. Zhang, Q. Guo, D. Zang, B. Wu, G. Fu, and N. Zheng, Photochemical route for synthesizing atomically dispersed palladium catalysts, Science 352, 797 (2016). 
3. X. Zhou, Q. Shen, K. Yuan, W. Yang, Q. Chen, Z. Geng, J. Zhang, X. Shao, W. Chen, G. Xu, X. Yang, and K. Wu, Unraveling charge state of supported Au single-atoms during CO oxidation, J. Am. Chem. Soc. 140, 554 (2018). 
4. L. Wang, H. Wang, and J. Lu, Local chemical environment effect in single-atom catalysis, Chem. Catal. 3, 100492 (2023). 
5. R. Qin, K. Liu, Q. Wu, and N. Zheng, Surface coordination chemistry of atomically dispersed metal catalysts, Chem. Rev. 120, 11810 (2020). 
6. P. Liu and N. Zheng, Coordination chemistry of atomically dispersed catalysts, Natl. Sci. Rev. 5, 636 (2018). 
7. J. Lu, Atomic Lego catalysts synthesized by atomic layer deposition, Acc. Mater. Res. 3, 358 (2022). 
8. J. Lu, J.W. Elam, and P.C. Stair, Synthesis and stabilization of supported metal catalysts by atomic layer deposition, Acc. Chem. Res. 46, 1806 (2013). 
9. J. Lu, J.W. Elam, and P.C. Stair, Atomic layer deposition—sequential self-limiting surface reactions for advanced catalyst “bottom-up” synthesis, Surf. Sci. Rep. 71, 410 (2016). 
10. J. Lu, B. Fu, M.C. Kung, G. Xiao, J.W. Elam, H.H. Kung, and P.C. Stair, Coking- and sintering-resistant palladium catalysts achieved through atomic layer deposition, Science 335, 1205 (2012). 
11. S.T. Christensen, J.W. Elam, F.A. Rabuffetti, Q. Ma, S.J. Weigand, B. Lee, S. Seifert, P.C. Stair, K.R. Poeppelmeier, M.C. Hersam, and M.J. Bedzyk, Controlled growth of platinum nanoparticles on strontium titanate nanocubes by atomic layer deposition, Small 5, 750 (2009). 
12. H. Yan, H. Cheng, H. Yi, Y. Lin, T. Yao, C. Wang, J. Li, S. Wei, and J. Lu, Single-atom Pd₁/graphene catalyst achieved by atomic layer deposition: remarkable performance in selective hydrogenation of 1,3-butadiene, J. Am. Chem. Soc. 137, 10484 (2015). 
13. H. Yan, H. Lv, H. Yi, W. Liu, Y. Xia, X. Huang, W. Huang, S. Wei, X. Wu, and J. Lu, Understanding the underlying mechanism of improved selectivity in Pd₁ single-atom catalyzed hydrogenation reaction, J. Catal. 366, 70 (2018). 
14. J. Li, Q. Guan, H. Wu, W. Liu, Y. Lin, Z. Sun, X. Ye, X. Zheng, H. Pan, J. Zhu, S. Chen, W. Zhang, S. Wei, and J. Lu, Highly active and stable metal single-atom catalysts achieved by strong electronic metal–support interactions, J. Am. Chem. Soc. 141, 14515 (2019). 
15. W.M.M. Kessels, H.C.M. Knoops, S.A.F. Dielissen, A.J.M. Mackus, and M.C.M. van de Sanden, Surface reactions during atomic layer deposition of Pt derived from gas phase infrared spectroscopy, Appl. Phys. Lett. 95, 013114 (2009). 
16. L. Wang, C. Zhu, M. Xu, C. Zhao, J. Gu, L. Cao, X. Zhang, Z. Sun, S. Wei, W. Zhou, W.-X. Li, and J. Lu, Boosting activity and stability of metal single-atom catalysts via regulation of coordination number and local composition, J. Am. Chem. Soc. 143, 18854 (2021). 
17. Y. Ren, Y. Tang, L. Zhang, X. Liu, L. Li, S. Miao, D.S. Su, A. Wang, J. Li, and T. Zhang, Unraveling the coordination structure–performance relationship in Pt₁/Fe₂O₃ single-atom catalyst, Nat. Commun. 10, 4500 (2019). 
18. Y. Li, Y. Xu, S. Chen, X. Shi, Q. Gu, L. Wang, M. Gu, B. Teng, B. Yang, and J. Lu, Tuning the electronic structures of anchor sites to achieve zero-valence single-atom catalysts for advanced hydrogenation, Angew. Chem. Int. Ed. 63, e202406262 (2024). 
19. A. Kudo and Y. Miseki, Heterogeneous photocatalyst materials for water splitting, Chem. Soc. Rev. 38, 253 (2009). 
20. X. Shi, Z. Wen, Q. Gu, L. Jiao, H.-L. Jiang, H. Lv, H. Wang, J. Ding, M.P. Lyons, A. Chang, Z. Feng, S. Chen, Y. Lin, X. Xu, P. Du, W. Xu, M. Sun, Y. Li, B. Yang, T. Zhang, X. Wu, and J. Lu, Metal–support frontier orbital interactions in single-atom catalysis, Nature 640, 668 (2025). 

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