Influence of Surface Roughness on the Work Function of Gold: A Density Functional Theory Study

The impact of surface roughness on the chemical reactivity of gold holds significant importance. This phenomenon can be elucidated from an electronic viewpoint by examining the work function as a fundamental material property. In this research, we investigated the relationship between the work function (WF) of gold and surface roughness using density functional theory calculations. Surface roughness was explored from two perspectives: (1) roughness density and (2) roughness geometry. The results demonstrate a correlation between increasing surface roughness and decreasing the work function of gold. The reduction in the work function, specifically from its initial value of 5.18–3.942 eV, signifies the transition of noble gold into a chemically active metal. Analysis of the density of states reveals the alternation in the distribution of energy bands, facilitating electron escape from the surface. Consequently, the increase in surface roughness density leads to a consistent decrease in the work function, aligning with Smoluchowski smoothing. However, when it comes to roughness induced by variations in geometric characteristics, these changes depend on the specific roughness pattern and no longer show a predictable correlation.