Experimental and Theoretical Study of Enhanced Photocatalytic Activity of Mg‐Doped ZnO NPs and ZnO/rGO Nanocomposites

Abstract

A systematic experimental and theoretical study of the origin of the enhanced photocatalytic performance of Mg-doped ZnO nanoparticles (NPs) and Mg-doped ZnO/reduced graphene oxide (rGO) nanocomposites has been performed. In addition to Mg, Cd was chosen as a doping material for the bandgap engineering of ZnO NPs, and its effects were compared with that of Mg in the photocatalytic performance of ZnO nanostructures. The experimental results revealed that Mg, as a doping material, recognizably ameliorates the photocatalytic performance of ZnO NPs and ZnO/graphene nanocomposites. Transmission electron microscopy (TEM) images showed that the Mg-doped and Cd-doped ZnO NPs had the same size. The optical properties of the samples indicated that Cd narrowed the bandgap, whereas Mg widened the bandgap of the ZnO NPs and the oxygen vacancy concentration was similar for both samples. Based on the experimental results, the narrowing of the bandgap, the particle size, and the oxygen vacancy did not enhance the photocatalytic performance. However, Brunauer-Emmett-Teller (BET) and Barret-Joyner-Halenda (BJH) models showed that Mg caused increased textural properties of the samples, whereas rGO played an opposite role. A theoretical study, conducted by using DFT methods, showed that the improvement in the photocatalytic performance of Mg-doped ZnO NPs was due to a higher electron transfer from the Mg-doped ZnO NPs to the dye molecules compared with pristine ZnO and Cd-doped ZnO NPs. Moreover, according to the experimental results, along with Mg, graphene also played an important role in the photocatalytic performance of ZnO.

Preparation of rGO/AgCl QDs and its enhanced photoelectrocatalytic performance for the degradation of Tetracycline

“…According to the calculation, BET surface area of AgCl QDs and rGO/AgCl QDs were 8.16 and 16.82 m 2 /g, respectively. It is clear that rGO plays an important role on increasing the specific surface area of the catalysts, which would provide more active sites, thus benefits the degradation performances of the samples …”

“…It is clear that rGO plays an important role on increasing the specific surface area of the catalysts, which would provide more active sites, thus benefits the degradation performances of the samples. 32,33 UV-vis diffuse reflectance tests (UV-vis DRS) of AgCl QDs and rGO/AgCl QDs are shown inFigure 6A. According to the UV/Vis absorption curves and Kubeka-Munk plots, the absorption of AgCl QDs is 391 nm with a band gap of 3.07 eV ( Figure S1B).…”

Synthesis and Characterization of ZnO-ZrO2 Nanocomposites for Photocatalytic Degradation and Mineralization of Phenol

“…In order to enhance optical properties of ZrO 2 several semiconductors like SiO 2 , TiO 2 , ZnO, WO 3 , and NiO have been coupled to ZrO 2 . Together with TiO 2 , zin oxide is one of the most investigated n-type semiconductor materials due to its low-cost, easy fabrication, wide band-gap, and photocatalytic activity for degrading several organic pollutants into less harmful products [9]. The main advantage of ZnO is that it absorbs a larger fraction of the solar spectrum than TiO 2 [10].…”

Enhanced Photocatalytic Activity of ZnO Toward the Degradation of Methylene Blue Dye: Effects of Fe3+ and Sn4+ Doping

“…Compared with undoped ZnO, all ZnO:Fe NCs are good photocatalysts, and the optimum doping concentration is 3%. Yousefi et al synthesized Mg‐ and Cd‐doped ZnO nanoparticles (NPs) by a sol–gel method. Theoretically, the improvement in the photocatalytic performance of Mg‐doped ZnO is due to higher electron transfer from the Mg‐doped ZnO NPs to the dye molecules compared with that from pristine ZnO and Cd‐doped ZnO NPs.…”