Probing Single Ni Sites in Crystalline Carbon Nitride via CO Adsorption and DRIFT-FTIR Spectroscopy
Palavras-chave:
DRIFT-FTIR, Single-atoms, adsorptionResumo
Crystalline carbon nitride (PHI) has emerged as a promising catalyst support due to its robust structure and favorable electronic properties, particularly for stabilizing isolated metal atoms. However, identifying isolated atoms remains challenging. This study employs CO adsorption as a probe, combined with DRIFT-FTIR, to investigate Ni²⁺ atoms doped into PHI. In Ni-PHI 0.5%, bands at 1190, 2135, and 2050 cm⁻¹ are attributed to chemisorbed, physiosorbed, and bridge-bonded CO, respectively. In Ni-PHI 4%, the bands shift to lower frequencies, with decreased intensity of chemisorbed and physiosorbed CO and predominance of bridge-bonded CO, indicating increased π-backdonation and the formation of Ni clusters or nanoparticles. DFT and DFT+U calculations support these findings, revealing structural and electronic features consistent with π-backdonation from Ni²⁺ to CO.
Referências
1. G. F. S. R. Rocha, M. A. R. da Silva, A. Rogolino, G. A. A. Diab, L. F. G. Noleto, M. Antonietti and I. F. Teixeira, Chemical Society Reviews, 2023, 52, 4878-4932.
2. G. Kresse and J. Furthmüller, Physical Review B, 1996, 54, 11169-11186.
3. P. E. Blöchl, Physical Review B, 1994, 50, 17953-17979.
4. J. P. Perdew, K. Burke and M. Ernzerhof, Physical Review Letters, 1996, 77, 3865-3868.
5. S. Grimme, J. Antony, S. Ehrlich and H. Krieg, The Journal of Chemical Physics, 2010, 132.
6. N. Allasia, S. Xu, S. F. Jafri, E. Borfecchia, L. A. Cipriano, G. Terraneo, S. Tosoni, L. Mino, G. Di Liberto, G. Pacchioni and G. Vilé, Small, n/a, 2408286.
7. G. Di Liberto, L. A. Cipriano and G. Pacchioni, ACS Catalysis, 2022, 12, 5846-5856.
8. I. V. Solovyev, P. H. Dederichs and V. I. Anisimov, Physical Review B, 1994, 50, 16861-16871.
9. V. Wang, N. Xu, J.-C. Liu, G. Tang and W.-T. Geng, Computer Physics Communications, 2021, 267, 108033.
10. M. A. R. da Silva, G. F. S. R. Rocha, G. A. A. Diab, C. S. Cunha, V. G. S. Pastana and I. F. Teixeira, Chemical Engineering Journal, 2023, 460, 141068.
11. G. Vilé, N. Allasia, S. Xu, S. Jafri, E. Borfecchia, L. Cipriano, G. Terraneo, S. Tosoni, L. Mino, G. Di Liberto and G. Pacchioni, Unveiling the true nanostructure of carbon nitride-supported single-atom catalysts, 2024.
12. C. C. Zhang, J. Shi, S. Hartlaub, J. P. Palamara, I. Petrovic and B. Yilmaz, Catalysis Communications, 2021, 150, 106273.
