The adsorption behavior of phenol on the surface of 1D/2D M@MoS2 (M = Co and Rh) for hydrodeoxidation reaction: Insights from theoretical investigations

As MoS₂ is a useful catalyst for phenol hydrodeoxidation, it is important to develop MoS₂ based catalysts. However, identifying active site remains challenging. In the present study, two monatomic catalysts, namely, Vs-Co@MoS₂ and Rh@MoS₂, were prepared and on which the adsorption sites of phenol were investigated via density functional theory (DFT). By systemically comparing the adsorption configuration, adsorption energy and adsorption distance, we found that the most stable configuration of phenol on 2D Vs-Co@MoS₂ monatomic catalyst was from η6 adsorption mode (horizontal adsorption; adsorption energy, −1.51 eV; adsorption distance, 1.7 Å), and the adsorption site was the Co-Vs interface that formed by an isolated Co atom and its adjacent S vacancy (Vs) site. The density of state (DOS) analysis indicated the adsorption active sites originated from defect states and orbital hybridization distribution near Fermi level. As for 1D Rh@MoS₂, the adsorption site was coming from the isolated Rh₁ atom, whose selectivity towards phenol was strengthened by the steric confinement effect of the unique pocket-like structure (Ho-Mo-Rh₁-Mo-OH). It was hoped that this study would provide important ideas for exploring the hydrodeoxygenation mechanism of phenol compounds.