The Adsorption Of Nitrobenzene, Azoxybenzene And Azobenzene On M₁₀₄（111）（M=Cu,Ag,Au） Surfaces: A Density Functional Theory Study

"Green Chemistry" is the dominant development of chemistry inthe21st century. Photocatalytic reaction is an important way toachieve green chemistry. Metal clusters photocatalyst of gold, silverand copper have become the focus of attention. Photocatalyticreactions by these metal clusters belong to heterogeneous catalysisreaction. The adsorption process is the most basic and necessaryprocess in photocatalytic reaction. Through the absorption, thecatalyst can promote the efficiency of the chemical reaction.Nitrobenzene is reduced by copper, silver and gold metal clusters,respectively. We systematically studied the adsorption ofnitrobenzene, reaction intermediates and reaction products on thesurface of metal clusters.In this paper, we have performed all calculations by theQUICKSTEP module of the CP2K package. The PBE functional of GGAin the framwork of DFT and BFGS optimization methods were used.We use a M104(M=Au，Ag and Cu) cluster as the models to investigatethe adsorption on the metal (111) surface. The DZVP-MOLOPT-SR-GTHbasis set was used in our calculations. Various adsorption sites were considered in our works to find the most adsorption structures. Forthe most stable structure, we analyzed the absorption molecule’sgeometry parameter, PDOS, Mulliken charge, and frontier molecularorbitals, and explored the interaction of nitrobenzene, azoxybenzeneand azobenzene with the transition metal surface Cu(111)、Ag(111)and Au(111).1. A DFT study of the adsorption of nitrobenzene (C6H5NO2) onCu104(111), Ag104(111) and Au104(111) surfacea) The adsorption of C6H5NO2on the boundary and face sites of thesurface of Cu104(111)、Ag104(111) and Au104(111) were investigated. Ourcalculations show that C6H5NO2favor the Boundary(111) site on allthe metal clusters.b) Then, we analyzed the Mulliken population, the PDOS andfrontier molecular orbitals of nitrobenzene on the surface ofBoundary(111). C6H5NO2interact with the surface through the O atom.The N-O bonds are remarkably elongated in the adsorption structures,especially on the Cu104(111) surface.2. A DFT study of the adsorption of azoxybenzene on Cu104(111),Ag104(111) and Au104(111) surfacea) The adsorption of C12H10N2O on the surface of Cu104(111)、Ag104(111) and Au104(111) were investigated. Our calculations showthat C12H10N2O favor the Boundary(111) site on all the metal clusters.b) The Mulliken population, the PDOS and frontier molecularOrbitals of azoxybenzene on the surface of Boundary(111) wereanalyzed. We also found that the N-O bonds are remarkably elongatedin the adsorption structures, especially on the Cu104(111) surface.3. A DFT study of the adsorption of azobenzene on Cu104(111), Ag104(111) and Au104(111) surfacea) The adsorption of azobenzene on the Cu104(111), Ag104(111) andAu104(111) were investigated. The results show that the Boundary(111)site is favored on all the metal surfaces.b) The Mulliken population, the PDOS and frontier molecularOrbitals of azobenzene on the surface of Boundary(111) wereanalyzed. We found that the large adsorption energy on the Cu surfaceis due to strong interaction of N atom to the Cu atom. When adsorbed,the N-N bond of azobenzene will be elongated.