Theoretical Study of CO2 Hydrogenation to HCOOH on Subnanometer PdZn Cluster
Marleni Wirmas\(^{(a)}\), Muhammad Haris Mahyuddin\(^{(b,c*)}\), Mohammad Kemal Agusta\(^{(b,c)}\), and Hermawan Kresno Dipojono\(^{(b,c)}\)

(a) Doctoral Program of Engineering Physics, Faculty of Industrial Technology, Institut Teknologi Bandung, Jl. Ganesha 10 Bandung 40132, Indonesia
(b) Quantum and Nano Technology Research Group, Faculty of Industrial Technology, Institut Teknologi Bandung, Jl. Ganesha 10 Bandung 40132, Indonesia
(c) Research Center for Nanoscience and Nanotechnology, Institut Teknologi Bandung, Jl. Ganesha 10 Bandung 40132, Indonesia

*mahyuddin133[at]itb.ac.id

Abstract

PdZn alloys have been potentially used as catalysts in various hydrogenation reactions, with each atom having significant roles in binding hydrogen and \(CO_{2}\) molecules. In this work, we conducted density functional theory (DFT) calculations to investigate the catalytic performance and reaction mechanism of \(CO_{2}\) hydrogenation to formic acid on a small, unsupported \(Pd_{5}Zn\) subnanocluster. Two reaction pathways are examined: the formate (HCOO) and carboxyl (COOH) routes. In the initial stage of \(CO_{2}\) as well as \(H_{2}\) adsorption, the molecules are adsorbed strongly with notable orbital hybridization between \(CO_{2}\), hydrogen, and PdZn atoms, suggesting an activated and well-suited condition for subsequent hydrogenation process. The preferred adsorption of all intermediates in the elementary reactions were investigated. Overall, intermediates in the formate pathway exhibit more stable adsorption and lower activation energies compared to those in the carboxyl pathway, making it the more favourable route in this system. These findings offer insights for designing efficient catalysts by utilizing subnanometer clusters to promote appropriate reaction intermediates.

Keywords: subnanometer cluster, \(CO_{2}\) hydrogenation, Density Functional Theory, heterogeneous catalyst

Topic: Instrumentation and Computational Physics