Effects of graphene oxide concentration on optical properties of ZnO/RGO nanocomposites and their application to photocurrent generation

Abstract

The effects of different concentrations of graphene oxide (GO) on the structure and optical properties of ZnO nanoparticles (NPs) were investigated. The nanocomposites were synthesized via the sol-gel method in a gelatin medium. X-ray diffraction patterns (XRD) and Fourier transform infrared spectroscopy indicated that the GO sheets were reduced and changed to reduced GO (RGO) during the calcination of the nanocomposites at 400 °C. In addition, the XRD patterns of the NPs indicated a hexagonal (wurtzite) structure for all the products. Microscopic studies showed that the NPs were decorated and dispersed on the RGO sheets very well. However, these studies revealed that the RGO concentration had an effect on the crystal growth process for the ZnO NPs. Furthermore, these studies showed that the NPs could be grown with a single crystal quality in an optimum RGO concentration. According to the XRD results that were obtained from pure ZnO NPs, the calcinations temperature was decreased by the RGO. UV–vis and room temperature photoluminescence studies showed that the optical properties of the ZnO/RGO nanocomposite were affected by the RGO concentration. Finally, the obtained ZnO/RGO nanocomposite was used to generate a photocurrent. Observations showed that the photocurrent intensity of the nanocomposite was significantly increased by increasing the RGO, with an optimum RGO concentration.

To investigate opulence of graphene in ZnO/graphene nanocomposites based dye sensitized solar cells

“…This results in a decrease of ZnO nanoparticles population in ZGR nanocomposites and hence the absorbance in the visible light gradually decreases. These results are in agreement with previous reports in semiconductor/ graphene nanocomposites [28,29]. Therefore, considerable influence of graphene concentration on the optical properties of these ZGR nanocomposites is observed.…”

“…Under irradiation, the photoinjected electrons on the conduction band of ZnO are trapped by the graphene sheets that could efficiently separate the photo-induced electrons and prevents the charge recombination thereby enhancing the photocatalytic performance of DSSCs based on ZGR nanocomposite photoanodes. Actually, the electronic interaction between ZnO and graphene improves the charge separation efficiency of these ZGR nanocomposites [27][28][29]. However, to generate a high photocurrent density, the optimum concentration of graphene is a key factor and need to be considered.…”

Multiple-layered structure of obelisk-shaped crystalline nano-ZnO prepared by sol–gel route

“…The soft-chemistry routes especially sol-gel procedures offer unique advantages such as the possibility of obtaining metastable materials, achieving superior purity and compositional homogeneity of the products at moderate temperatures with simple laboratory equipment [21]. Semiconductor photo-catalysts offer huge potential for elimination of toxic chemicals [22]. ZnO, with bang gap = 3.37 eV, has become promising in the past few years because of its distinctive optoelectronic, catalytic, and photochemical properties [24,25].…”

Band alignment tuned by 3-PPA SAMs interfacial modification to enhance the conversion efficiency of ZnO/ZnS heterostructure quantum dots sensitized solar cells

“…The UV emission is attributed to the near band edge (NBE) emission of ZnO [31][32][33]. The green emission band is originated from ionized oxygen vacancies [34][35][36]. As shown in Fig.…”