One-pot hydrothermal synthesis of ZnS–reduced graphene oxide composites with enhanced photocatalytic properties

Abstract

A simple route for the preparation of ZnS-reduced graphene oxide (RGO) composites via a one-pot hydrothermal synthesis is achieved. The chemical composition, morphology and structure of the ZnS-RGO samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N 2 adsorption-desorption specific surface area analysis (BET) and diffuse reflectance absorption (DRS). The results show that the ZnS nanoparticles were well dispersed on the RGO nanosheets which serve as the ZnS nanocrystal growth support and the morphology controller. It was found that the specific surface area of the ZnS-RGO composites increased with the incorporation of RGO. The ZnS-RGO composites were used as photocatalysts for the degradation of methylene blue (MB) under UV light irradiation. The results show the ZnS-RGO composites exhibited better photocatalytic activity and photodegradation kinetics compared with pure ZnS and commercial TiO 2 (P25) which is attributed to the high specific surface area and the hindrance of electron-hole pair recombination of ZnS due to the RGO incorporation. Therefore, the RGO has a positive effect on the ZnS-RGO composite as a photocatalyst.

Reduced graphene oxide wrapped ZnS–Ag2S ternary composites synthesized via hydrothermal method: Applications in photocatalyst degradation of organic pollutants

“…The peak that appeared at ∼1630 cm −1 was related to aromatic C C. The peaks at ∼1227 cm −1 (epoxy C O) and ∼1055 (alkoxy C O) vibrations [40], indicating the existence of oxygen-containing functional groups on the GO nanosheets. For the ZnS-Ag 2 S-RGO composite, a series of additional absorption peaks at 3440, 1689, 1548 and 1174 cm −1 appeared and were characteristic of C O, C OH, and C O stretching vibrations related to the functional groups in GO [40]; these results indicates that some of the oxygen-containing groups at the edges of the GO sheets is remained in the composite. However, compared with pure GO, the intensities of the peaks corresponding to oxygen-containing functional groups in the ZnS-Ag 2 S-RGO composite, decreased significantly and even disappeared at several of the absorption peak positions, indicating that GO was reduced after the hydrothermal reaction.…”

“…The spectral bands situated at ∼1726 cm −1 and ∼1377 cm −1 were assigned to the characteristic stretching vibration of carboxyl C O and C O respectively [40]. The peak that appeared at ∼1630 cm −1 was related to aromatic C C. The peaks at ∼1227 cm −1 (epoxy C O) and ∼1055 (alkoxy C O) vibrations [40], indicating the existence of oxygen-containing functional groups on the GO nanosheets. For the ZnS-Ag 2 S-RGO composite, a series of additional absorption peaks at 3440, 1689, 1548 and 1174 cm −1 appeared and were characteristic of C O, C OH, and C O stretching vibrations related to the functional groups in GO [40]; these results indicates that some of the oxygen-containing groups at the edges of the GO sheets is remained in the composite.…”

“…6. The strong and broad absorption peak located at 3402 cm −1 in the spectrum of GO, was attributed to the O H stretching vibrations [40]. The spectral bands situated at ∼1726 cm −1 and ∼1377 cm −1 were assigned to the characteristic stretching vibration of carboxyl C O and C O respectively [40].…”

“…The strong and broad absorption peak located at 3402 cm −1 in the spectrum of GO, was attributed to the O H stretching vibrations [40]. The spectral bands situated at ∼1726 cm −1 and ∼1377 cm −1 were assigned to the characteristic stretching vibration of carboxyl C O and C O respectively [40]. The peak that appeared at ∼1630 cm −1 was related to aromatic C C. The peaks at ∼1227 cm −1 (epoxy C O) and ∼1055 (alkoxy C O) vibrations [40], indicating the existence of oxygen-containing functional groups on the GO nanosheets.…”

Novel synthesis of silver/reduced graphene oxide nanocomposite and its high catalytic activity towards hydrogenation of 4-nitrophenol

“…22 Further, in order to efficiently compare the catalytic activities of Ag/RGO and other substrate-supported Ag or Au nanocatalysts. The apparent rate constant (K) was calculated by the following equation based on the pseudo-first-order reaction: ln(C t /C 0 ) = -Kt, 23 where K, C t , and C 0 are apparent rate constant, initial concentration and residual concentration of 4-NP at different intervals, respectively. The apparent rate constant was determined as 0.38952 min -1 (Fig.…”