Ab initio investigation of quantum size effects on the adsorption of CO2, CO, H2O, and H-2 on transition-metal particles

Author(s)

Mendes, Paulo C. D. ^[1] ; Ocampo-Restrepo, Vivianne K. ^[1] ; Da Silva, Juarez L. F. ^[1]

Affiliation

^[1] Univ Sao Paulo, Sao Carlos Inst Chem, POB 780, BR-13560970 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: Physical Chemistry Chemical Physics; v. 22, n. 16, p. 8998-9008, APR 28 2020.
• Web of Science Citations: 7

Abstract

Adsorption is a crucial preliminary step for the conversion of CO2 into higher-value chemicals, nonetheless, the atomistic understanding of how substrate particle size affects this step is still incomplete. In this study, we employed density functional theory to investigate the effects of particle size on the adsorption of model molecules involved in the CO2 transformations (CO2, CO, H2O and H-2) on Co-n, Ni-n and Cu-n particles with different sizes (n = 13, 55, 147) and on the respective close-packed surfaces. We found significant size-dependence of the adsorption properties for physisorbed (linear) and chemisorbed (bent) CO2 on the substrates and distinct (symmetric or asymmetric) stretching of the C-O bonds, which can play a crucial role to understand the CO2 dissociation pathways. For CO and H-2, some properties showed small oscillations, due to size effects that induced alternation of the adsorption site preference for different particle sizes; for H2O, the adsorption properties were almost independent of particle size. The presence of low-coordinated adsorption sites resulted in a trend for stronger adsorption and greater charge transfer for smaller clusters. Fixing the size-independent factors (e.g., type of metal), our results show that CO2 adsorption on transition-metal clusters is significantly affected by particle size, suggesting that substrate particle size could be a key factor to understand and control the catalytic transformations of CO2. (AU)

• FAPESP's process: 18/21401-7 - Multi-User Equipment approved in grant 2017/11631-2: cluster computational de alto desempenho - ENIAC
• Grantee: Juarez Lopes Ferreira da Silva
• Support Opportunities: Multi-user Equipment Program
• FAPESP's process: 17/11631-2 - CINE: computational materials design based on atomistic simulations, meso-scale, multi-physics, and artificial intelligence for energy applications
• Grantee: Juarez Lopes Ferreira da Silva
• Support Opportunities: Research Grants - Research Centers in Engineering Program