Morphology Dependent Reactivity of CsO$$x$$ Nanostructures on Au(111): Binding and Hydrogenation of CO2 to HCOOH
[1];
[1];
[1];
[5];
[5];
[6];
[6]
- Brookhaven National Laboratory (BNL), Upton, NY (United States). Chemistry Division
- Brookhaven National Laboratory (BNL), Upton, NY (United States). Chemistry Division; Loyola University, Chicago, IL (United States)
- Stony Brook University, NY (United States)
- Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II); Brookhaven National Laboratory (BNL), Upton, NY (United States). Chemistry Division
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, United States
- Brookhaven National Laboratory (BNL), Upton, NY (United States). Chemistry Division; Stony Brook University, NY (United States)
Cesium oxide (CsO$$x$$) nanostructures grown on Au(111) behave as active centers for CO2 binding and hydrogenation reactions. The morphology and reactivity of these CsO$$x$$ systems were investigated as a function of alkali coverage using scanning tunnelling microscopy (STM), ambient pressure X-ray photoelectron spectroscopy (AP-XPS), and density functional theory (DFT) calculations. STM results show that initially (0.05 - 0.10 ML) cesium oxide clusters (Cs2O2) grow at the elbow sites of the herringbone of Au(111), subsequently transforming into two-dimensional islands with increasing cesium coverage (> 0.15 ML). XPS measurements reveal the presence of suboxidic (Cs$$y$$O; $$y$$ ≥ 2) species for the island structures. The higher coverages of cesium oxide nanostructures contain a lower O/Cs ratio resulting in a stronger binding of CO2. Moreover, the O atoms in the Cs$$y$$O structure undergo a rearrangement upon the adsorption of CO2 which is a reversible phenomenon. Under CO2 hydrogenation conditions, the small Cs2O2 clusters are hydroxylated, thereby preventing the adsorption of CO2. However, the hydroxylation of the higher coverages of Cs$$y$$O did not prevent CO2 adsorption, and the adsorbed CO2 transformed to HCOO species that eventually yield HCOOH. DFT calculations further confirm that the dissociated H2 attacks the C in the adsorbate to produce formate, which is both thermodynamically and kinetically favored during the CO2 reaction with hydroxylated Cs$$y$$O. These results demonstrate that cesium oxide by itself is an excellent catalyst for CO2 hydrogenation that could produce formate, an important intermediate for the generation of value-added species. The role of the alkali oxide nanostructures as active centers, not merely as promoters, may have broad implications wherein the alkali oxides can be considered in the design of materials tuned for specific applications in heterogeneous catalysis.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
- Grant/Contract Number:
- AC02-05CH11231; SC0012704
- OSTI ID:
- 2222891
- Report Number(s):
- BNL-225034-2023-JAAM
- Journal Information:
- ACS Nano, Vol. 17, Issue 22; ISSN 1936-0851
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Structure and Chemical State of Cesium on Well-Defined Cu(111) and Cu2O/Cu(111) Surfaces
Morphology and chemical behavior of model CsOx/Cu2O/Cu(111) nanocatalysts for methanol synthesis: Reaction with CO2 and H2