First-principles study of the co-effect of carbon doping and oxygen vacancies in ZnO photocatalyst*

Abstract

Although tuning band structure of optoelectronic semiconductor-based materials by means of doping single defect is an important approach for potential photocatalysis application, C-doping or oxygen vacancy (Vo) as a single defect in ZnO still has limitations for photocatalytic activity. Meanwhile, the influence of co-existence of various defects in ZnO still lacks sufficient studies. Therefore, we investigate the photocatalytic properties of ZnO x C0.0625 (x = 0.9375, 0.875, 0.8125), confirming that the co-effect of various defects has a greater enhancement for photocatalytic activity driven by visible-light than the single defect in ZnO. To clarify the underlying mechanism of co-existence of various defects in ZnO, we perform systematically the electronic properties calculations using density functional theory. It is found that the co-effect of C-doping and Vo in ZnO can achieve a more controllable band gap than doping solely in ZnO. Moreover, the impact of the effective masses of ZnO x C0.0625 (x = 0.9375, 0.875, 0.8125) is also taken into account. In comparison with heavy Vo concentrations, the light Vo concentration (x = 0.875) as the optimal component together with C-doping in ZnO, can significantly improve the visible-light absorption and benefit photocatalytic activity.

First-principle study of the effect of point defects on the activity, carrier lifetime, and photocatalytic performance of ZnO:(S/Se/Te) system

“…The tolerance shift convergence accuracy was 0.001 Å. Due to the strong correlation between the Zn-3d electrons and O-2p electrons of ZnO [29], GGA could not accurately describe the interaction between electrons in this system, leading to an underestimation of the bandgap of ZnO. The calculated bandgap value was only 0.74 eV, lower than the experimental value (3.40 eV) [10].…”

High-quality CdS quantum dots sensitized ZnO nanotube array films for superior photoelectrochemical performance

“…ZnO is a typical semiconductor material that has been widely applied in solar cells, photocatalysis, water splitting and other photoelectrochemical (PEC) fields [1][2][3][4][5][6][7][8] due to its advantages such as non-toxicity, low cost, suitable energy band position, good chemical stability and resistance to photocorrosion. [9][10][11][12] In spite of this, it must be pointed out that there are two inherent drawbacks of ZnO for its application in PEC devices.…”