Abstract
The structural stability, electronic structure, and optical properties of an iron-adsorbed ZnO (0001) surface with three high-symmetry adsorption sites are investigated with first-principle calculations on the basis of density functional theory and the Hubbard-U method. It is found that the iron adatom in the H3 adsorption site of ZnO (0001) surface has the lowest adsorption energy of −5.665 eV compared with T4 and Top sites. For the Top site, compared with the pristine ZnO (0001) surface, the absorption peak located at 1.17 eV has a red shift, and the elevation of the absorption coefficient is more pronounced in the visible-light region, because the Fe-related levels are introduced in the forbidden band and near the Fermi level. The electrostatic potential computation reveals that the work function of the ZnO (0001) surface is significantly decreased from 2.340 to 1.768 eV when iron is adsorbed on the Top site. Furthermore, the degradation mechanism based on the band structure is analyzed. It can be concluded that the adsorption of iron will promote the separation of photoinduced carriers, thus improving the photocatalytic activity of ZnO (0001) surface. Our study benefits research on the photocatalytic activity of ZnO and the utilization rate of solar energy.
Highlights
In recent years, with increasingly serious environmental pollution and energy shortage, semiconductor-based photocatalysts have aroused great interest
Zhang et al [21] investigated these four surfaces by first-principle calculations with Vienna ab initio simulation package (VASP) and confirmed that (0001)-Zn surface had the strongest absorption in the near UV region range among these four surfaces and a remarkable red-shift phenomenon of the absorption edge compared with the bulk Zinc oxide (ZnO), indicating that (0001)-Zn surface had the highest photocatalytic activity with low photon energy
This paper presents a theoretical investigation of the effect of iron atom adsorption on the structural stability, electronic structure, and optical properties of a ZnO (0001) surface using first-principle computations
Summary
With increasingly serious environmental pollution and energy shortage, semiconductor-based photocatalysts have aroused great interest. Some experimental and theoretical works have been undertaken to enhance the absorption coefficient of ZnO under visible light irradiation with foreign element-doping and the surface modification of, for example, semiconductor composite and noble metal composite structures [14,15,16,17,18]. Zhang et al [21] investigated these four surfaces by first-principle calculations with VASP and confirmed that (0001)-Zn surface had the strongest absorption in the near UV region range among these four surfaces and a remarkable red-shift phenomenon of the absorption edge compared with the bulk ZnO, indicating that (0001)-Zn surface had the highest photocatalytic activity with low photon energy. Zhang et al [27] investigated Si-adsorbed ZnO (0001) surface by first-principle calculations and observed that H3 sites played a critical role in the red shift of absorption edge.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
