First-principles study of O_2 adsorption on Al-doped ZnO(1010) surface

摘要

Understanding the O_2 adsorption on the Al-doped ZnO surface is crucial to unravel its enhanced sensing performances toward reducing gases (such as CO and H_2) compared with its undoped counterpart. We have studied the O_2 adsorption on the defect-free Al-doped ZnO(1010) surface by using first-principles calculations. It is found that Al doping introduces electrons into the conduction band of the ZnO(1010) surface, which should significantly enhance the conductance of the oxide. The adsorbed O_2 can effectively acquire electrons from the Al-doped ZnO(1010) surface, leading to the decrease in the conductance of the materials. Upon gaining electrons, the adsorbed O_2 molecules on the Al-doped ZnO(1010) surfaces exist in the form of superoxo O_2~- species, which are expected to be chemically active toward reducing gases.