The influence of Sn modification towards surface reactivity of Pt(111) in catalytic glycerol oxidation reaction: A DFT-D3 study

Glycerol production keeps increasing in recent years, underscoring the need for its conversion into other valuable chemicals. One popular method is through oxidation process which generates numerous possibilities for product formation, including glyceraldehyde (GLAD) and dihydroxyacetone (DHA). In this study, we employed density functional theory (DFT) method to investigate the catalytic activity of Sn-modified Pt(111) on glycerol oxidation reaction (GOR). Herein, we describe two types of Sn modification, viz., Pt atomic replacement and Sn cluster anchoring. Different Sn addition leads to distinct effects on the structural and electronic properties of Pt(111). Notably, the presence of stable Sn 4 cluster on Pt(111) surface successfully enhances glycerol adsorption due to synergistic effect between Pt and Sn atoms while Sn substitution weakens the adsorption process. Furthermore, electronic properties of Pt(111) are also improved after Sn 4 addition, including d-band centre closer to the Fermi level and charge redistribution on the interfacial Pt-Sn region. Glycerol adsorption energy on Sn 4 -Pt(111) was calculated to be −1.16 eV. Detailed investigation on O-H and C-H bond cleavage are performed to construct an energy diagram of the GOR. From the energetics aspect, bimetallic PtSn was found to be more selective towards GLAD production. The rate-determining step is profiled to be the O-H cleavage with an energy barrier of 0.61 eV. Regarding DHA production, the Sn 4 cluster appears to be distorted during the reaction process which suggests unsuitability of the modelled catalyst. Overall, the results from this work provide valuable insights on elucidating GOR mechanism over Sn-modified Pt(111) surface.