Dynamic restructuring drives catalytic activity on nanoporous gold–silver alloy catalysts
Source abstract
Abstract
Bimetallic, nanostructured materials hold promise for improving catalyst activity and selectivity, yet little is known about the dynamic compositional and structural changes that these systems undergo during pretreatment that leads to efficient catalyst function. Here we use ozone-activated silver-gold alloys in the form of nanoporous gold as a case study to demonstrate the dynamic behaviour of bimetallic systems during activation to produce a functioning catalyst. We show that it is these dynamic changes that give rise to the observed catalytic activity. Advanced in situ electron microscopy and X-ray photoelectron spectroscopy are used to demonstrate that major restructuring and compositional changes occur along the path to catalytic function for selective alcohol oxidation. Transient kinetic measurements correlate the restructuring to three types of oxygen on the surface. The direct influence of changes in surface silver concentration and restructuring at the nanoscale on oxidation activity is demonstrated. Our results demonstrate that characterization of these dynamic changes is necessary to unlock the full potential of bimetallic catalytic materials.
Source: europepmc · Quality: candidate unverified · Source record ↗
Research context
OpenAlex topics: Nanoporous metals and alloys · Electrocatalysts for Energy Conversion · Catalytic Processes in Materials Science
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
References (32)
Show source-provided references
1. Behrens, M. et al. The active site of methanol synthesis over Cu/ZnO/Al2O3 industrial catalysts. Science 336, 893–897 (2012).10.1126/science.1219831 ↗
2. Xin, H. L. et al. Revealing the atomic restructuring of Pt–Co nanoparticles. Nano Lett. 14, 3203–3207 (2014).10.1021/nl500553a ↗
3. Tao, F. et al. Reaction-driven restructuring of Rh–Pd and Pt–Pd core–shell nanoparticles. Science 322, 932–934 (2008).10.1126/science.1164170 ↗
4. Brett, G. L. et al. Selective oxidation of glycerol by highly active bimetallic catalysts at ambient temperature under base-free conditions. Angew. Chem. 123, 10318–10321 (2011).10.1002/ange.201101772 ↗
5. Della Pina, C., Falletta, E. & Rossi, M. Highly selective oxidation of benzyl alcohol to benzaldehyde catalyzed by bimetallic gold–copper catalyst. J. Catalys. 260, 384–386 (2008).10.1016/j.jcat.2008.10.003 ↗
6. Whiting, G. T. et al. Methyl formate formation from methanol oxidation using supported gold–palladium nanoparticles. ACS Catalys. 5, 637–644 (2015).10.1021/cs501728r ↗
7. Kotionova, T. et al. Oxidative esterification of homologous 1,3-propanediols. Catalys. Lett. 142, 1114–1120 (2012).10.1007/s10562-012-0872-7 ↗
8. Suzuki, K. et al. Aerobic oxidative esterification of aldehydes with alcohols by gold–nickel oxide nanoparticle catalysts with a core–shell structure. ACS Catalys. 3, 1845–1849 (2013).10.1021/cs4004084 ↗
9. Stowers, K. J., Madix, R. J. & Friend, C. M. From model studies on Au(111) to working conditions with unsupported nanoporous gold catalysts: oxygen-assisted coupling reactions. J. Catalys. 308, 131–141 (2013).10.1016/j.jcat.2013.05.033 ↗
10. Wang, L.-C. et al. Exploiting basic principles to control the selectivity of the vapor phase catalytic oxidative cross-coupling of primary alcohols over nanoporous gold catalysts. J. Catalys. 329, 78–86 (2015).10.1016/j.jcat.2015.04.022 ↗
11. Sault, A. G., Madix, R. J. & Campbell, C. T. Adsorption of oxygen and hydrogen on Au(110)-(1 × 2). Surf. Sci. 169, 347–356 (1986).10.1016/0039-6028(86)90616-3 ↗
12. Meyer, R., Lemire, C., Shaikhutdinov, S. K. & Freund, H. J. Surface chemistry of catalysis by gold. Gold Bull. 37, 72–124 (2011).10.1007/BF03215519 ↗
13. Personick, M. L. et al. Ozone-activated nanoporous gold: a stable and storable material for catalytic oxidation. ACS Catalys. 5, 4237–4241 (2015).10.1021/acscatal.5b00330 ↗
14. Xu, C. et al. Low temperature CO oxidation over unsupported nanoporous gold. J. Am. Chem. Soc. 129, 42–43 (2007).10.1021/ja0675503 ↗
15. Biener, M. M. et al. ALD functionalized nanoporous gold: thermal stability, mechanical properties, and catalytic activity. Nano Lett. 11, 3085–3090 (2011).10.1021/nl200993g ↗
16. Fujita, T. et al. Atomic origins of the high catalytic activity of nanoporous gold. Nat. Mater. 11, 775–780 (2012).10.1038/nmat3391 ↗
17. Xu, B., Liu, X., Haubrich, J., Madix, R. J. & Friend, C. M. Selectivity control in gold-mediated esterification of methanol. Angew. Chem. Int. Ed. 48, 4206–4209 (2009).10.1002/anie.200805404 ↗
18. Xu, B., Haubrich, J., Freyschlag, C. G., Madix, R. J. & Friend, C. M. Oxygen-assisted cross-coupling of methanol with alkyl alcohols on metallic gold. Chem. Sci. 1, 310–316 (2010).10.1039/c0sc00214c ↗
19. Wang, L. C. et al. Active sites for methanol partial oxidation on nanoporous gold catalysts. J. Catalys. 344, 778–783 (2016).10.1016/j.jcat.2016.08.012 ↗
20. in Non-tetrahedrally Bonded Elements and Binary Compounds I Vol. 41C (eds Madelung, O., Rössler, U. & Schulz, M.) 1–3 (Springer, 1998).
21. Jones, P. G. et al. Gold(III) oxide. Acta Crystallogr. B 35, 1435–1437 (1979).10.1107/S0567740879006622 ↗
22. Krozer, A. & Rodahl, M. X-ray photoemission spectroscopy study of UV/ozone oxidation of Au under ultrahigh vacuum conditions. J. Vac. Sci. Technol. A 15, 1704–1707 (1997).10.1116/1.580924 ↗
23. Tanuma, S., Powell, C. J. & Penn, D. R. Calculations of electron inelastic mean free paths. Surf. Interface Anal. 21, 165–176 (1994).10.1002/sia.740210302 ↗
24. Kaspar, T. C., Droubay, T., Chambers, S. A. & Bagus, P. S. Spectroscopic evidence for Ag(III) in highly oxidized silver films by X-ray photoelectron spectroscopy. J. Phys. Chem. C 114, 21562–21571 (2010).10.1021/jp107914e ↗
25. Hammond, J. S. & Gaarenstroom, S. W. X-ray photoelectron spectroscopic studies of cadmium– and silver–oxygen surfaces. Anal. Chem. 47, 2193–2199 (1975).10.1021/ac60363a019 ↗
26. Hoflund, G. B., Hazos, Z. F. & Salaita, G. N. Surface characterization study of Ag, AgO, and Ag2O using x-ray photoelectron spectroscopy and electron energy-loss spectroscopy. Phys. Rev. B 62, 11126–11133 (2000).10.1103/PhysRevB.62.11126 ↗
27. Xu, B., Siler, C. G. F., Madix, R. J. & Friend, C. M. Ag/Au mixed sites promote oxidative coupling of methanol on the alloy surface. Chem. Eur. J. 20, 4646–4652 (2014).10.1002/chem.201304837 ↗
28. Boronin, A. I., Koscheev, S. V. & Zhidomirov, G. M. XPS and UPS study of oxygen states on silver. J. Electron Spectrosc. Relat. Phenom. 96, 43–51 (1998).10.1016/S0368-2048(98)00221-7 ↗
29. Tyson, C. C. et al. Charge redistribution in Au–Ag alloys from a local perspective. Phys. Rev. B 45, 8924–8928 (1992).10.1103/PhysRevB.45.8924 ↗
30. Kibis, L. S. et al. The investigation of oxidized silver nanoparticles prepared by thermal evaporation and radio-frequency sputtering of metallic silver under oxygen. Appl. Surf. Sci. 257, 404–413 (2010).10.1016/j.apsusc.2010.07.002 ↗
31. Moskaleva, L. V., Weiss, T., Klüner, T. & Bäumer, M. Chemisorbed oxygen on the Au(321) surface alloyed with silver: a first-principles investigation. J. Phys. Chem. C 119, 9215–9226 (2015).10.1021/jp511884k ↗
32. Fujita, T. et al. Atomic observation of catalysis-induced nanopore coarsening of nanoporous gold. Nano Lett. 14, 1172–1177 (2014).10.1021/nl403895s ↗