Influence of surface charge density on ligand-metal bonding: A DFT study of NH3 and HCOOH on Mg (0001) surface

Abstract

Activation of the ligand binding to substrate is a highly desirable, yet challenging reaction for biomolecular coaling on the biomedical material surface. One advantage of this process is their modular construction on the surface as the biomolecular linkers, allowing for flexible design and detailed control of certain properties. In this work, we studied the binding properties of NH3 and HCOOH on Mg (0 0 0 1) surface and tried to understand the effect of alloy elements in the binding process. First principles within density functional theory (DFT) has been used to investigate the adsorption of NH3 and HCOOH molecules on Mg (0 0 0 1) and Zn-(Y-) doped surfaces. The electron redistribution, effect of alloy element and changes in the density of states of interaction systems are analyzed. Our results revealed that NH3 and HCOOH interact with the Mg (0 0 0 1) surface through dative bond with the adsorption energy(E-ads) -0.70 and -0.64 eV, and the Zn/Y alloy element can improve the adsorption process which accompanied by charge-transfer between substrate and adsorbate. Calculated results of the nudged elastic band (NEB) show that the energy barrier of 0.14 eV need to be overcome for NH3 from the neighbor site to Y atom. Our findings provide insight for the binding mechanism of ligand on Mg and Mg-based alloy surfaces and also point out some directions for future experimental efforts.