The effect of Ag doping and point defects on the electronic structure and photocatalytic properties of ZnO using first-principles

Abstract

At present, the photocatalytic properties of Ag-doped ZnO have been extensively studied, but the mechanism of Ag-doped ZnO photocatalysis is not fully understood. The effect of intrinsic point defects on the performance and mechanism of Ag-doped ZnO photocatalysis has rarely been studied by theoretical calculations. To solve such problems, first-principle calculations were performed to systematically investigate the effect of Ag doping (AgZn/Agi) and point vacancy (VZn/VO) on the photocatalytic performance and mechanism of ZnO. It was found that the ZnO:Agi+VZn showed the strongest structural stability compared to the three doping methods, ZnO:AgZn+VZn, ZnO:AgZn+VO, and ZnO:Agi+VO. In addition, the doping of interstitial Ag with Zn vacancy shrank the ZnO bandgap to the smallest bandgap width (2.46 eV), thereby broadening the ZnO absorption spectrum into the visible range. The study of the dipole moment, static dielectric constant, and carrier effective mass showed that the ZnO:Agi+VZn exhibited excellent photocatalytic polarization and activity in the visible range. In particular, along the [001] direction, electrons and holes showed stronger mobility, resulting in effective separation and transfer of electron-hole pairs and a reduction in the electron-hole complex rate. The results provided a theoretical reference for in-depth understanding and designing of novel ZnO photocatalysts.

Imperfect makes perfect: defect engineering of photoelectrodes towards efficient photoelectrochemical water splitting

“…146 Similarly, ZnO also has a large bandgap and its photocorrosion issue leads to very poor stability for PEC water splitting. 147 Besides, some metal oxide semiconductors such as α-Fe 2 O 3 , WO 3 , BiVO 4 and SrTiO 3 have been intensively studied due to the low cost, narrow bandgap and high stability. 148 However, these metal oxides exhibit low STH efficiencies (<10%) due to inherently low electron mobility and low separation efficiency of photogenerated carriers, which limits their practical application for PEC water splitting.…”

Ag-Doped CdSe Nanosheets as Photocatalysts for Uranium Reduction

“…Element Ag doping is widely used in the modification of semiconductor materials. Doping Ag in semiconductors can effectively shorten the band gap of semiconductors, thus causing the absorption spectrum of semiconductor materials to expand to the visible range. − In addition, Ag doping can also improve conductivity, thereby accelerating electron transfer . In particular, the built-in electric field generated by Ag doping can make electrons and holes exhibit strong mobility, thus effectively separating and transferring electron–hole pairs and reducing the electron–hole recombination ratio. , Therefore, Ag doping is a very promising strategy for modifying 2D materials.…”

Optimization of the structural and optical properties of ALD grown ZnO thin films for photocatalytic applications: thickness dependence

“…Thus, it has been employed to develop many applications including UV photodetectors, acoustic devices, optoelectronic devices, gas sensors, chemical sensors, light sensors, spintronics, varistors, ceramic matrices, solar cells and non-volatile memories [1][2][3][4][5]. Also, ZnO is employed as photocatalyst to treat the water or surfaces from the toxic byproducts and organic dyes due to high concentration and fast mobility of photogenerated carriers which transfer swiftly from the photocatalyst to the dye [2,[5][6][7].…”