DFT study of the formation of Cd–Ag surface alloys on Ag surfaces

•DFT calculations verify Cd tendency to adsorb on the Ag surface in an ordered way.•We model two mechanisms for the formation of the surface alloy.•Ag and Cd energetic preference to stay in alloyed form onto Ag surface was tested.•We justified alloy formation mechanism based on electrochemical measurements.•The Ag–Cd bond in surface alloy is stronger due to considerable charge transfer.