Visible-light-induced WO3/g-C3N4 composites with enhanced photocatalytic activity

Abstract

Novel WO3/g-C3N4 composite photocatalysts were prepared by a calcination process with different mass contents of WO3. The photocatalysts were characterized by thermogravimetric analysis (TG), powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflection spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and electrochemical impedance spectroscopy (EIS). The photocatalytic activity of the photocatalysts was evaluated by degradation of methylene blue (MB) dye and 4-chlorophenol (4-CP) under visible light. The results indicated that the WO3/g-C3N4 composite photocatalysts showed higher photocatalytic activity than both the pure WO3 and pure g-C3N4. The optimum photocatalytic activity of WO3/g-C3N4 at a WO3 mass content of 9.7% under visible light irradiation was up to 4.2 times and 2.9 times as high as that of the pure WO3 and pure g-C3N4, respectively. The remarkably increased performance of WO3/g-C3N4 was mainly attributed to the synergistic effect between the interface of WO3 and g-C3N4, including enhanced optical absorption in the visible region, enlarged specific surface areas and the suitable band positions of WO3/g-C3N4 composites.

Construction of stable Ta 3 N 5 /g-C 3 N 4 metal/non-metal nitride hybrids with enhanced visible-light photocatalysis

“…Herein, the PL spectra of pure g-C 3 N 4 and Ta 3 N 5 /g-C 3 N 4 composites were excited by irradiation of wavelength 350 nm. It can be seen that the main PL emission peak of pure g-C 3 N 4 is at about 460 nm, because the energy of emission light resembles to the E g of g-C 3 N 4 [51], which is in agreement with the result of the UV-vis analysis. When Ta 3 N 5 was combined with g-C 3 N 4 , the emission intensity of Ta 3 N 5 /g-C 3 N 4 composites observed is smaller than that of pure g-C 3 N 4 with the emission peak at nearly the same position, and 2-Ta 3 N 5 /g-C 3 N 4 sample has the weakest intensity.…”

Ball-milling combined calcination synthesis of In2O3/C3N4 for high photocatalytic activity under visible light irradiation

“…It indicated that In 2 O 3 /C 3 N 4 (17.3%) composite had lower resistance than that of C 3 N 4 . This result confirmed that the introduction In 2 O 3 into C 3 N 4 can enhance the separation and transfer efficiency of photogenerated electron-hole pairs [44], which was benefit to the enhancement of photocatalytic activity.…”

“…The calculated top VB and bottom CB of In 2 O 3 were 2.12 eV and −0.56 eV, respectively. For C 3 N 4 , the top VB and the bottom CB were 1.57 eV and −1.13 eV, respectively [44]. Upon irradiated by visible light (>400 nm), both In 2 O 3 and C 3 N 4 can be activated in the composites.…”

“…However, effectively separation of electron and holes depended on whether the two kinds of semiconductor materials had suitable position of band gaps. It was conducive to the separation of electrons and holes due to the suitable band gap structure of two kinds of semiconductor materials [44]. According to the structure characteristics and the photocatalytic performance tests of C 3 N 4 / In 2 O 3 composite, a possible mechanism was presented and showed in Fig.…”

The synergistic effect between WO3 and g-C3N4 towards efficient visible-light-driven photocatalytic performance

“…Moreover, in the synergism of WO 3 -g-C 3 N 4 , the former component helps to reduce the recombination rate of electron-hole pairs while the latter one enhances the active sites of the catalyst surface. 43,44 Herein, we have presented for the first time a morphology-based novel WO 3 -g-C 3 N 4 (1D/2D) synergetic hybrid system fabricated by a simple hydrothermal and annealing method which exhibited superior photocatalytic activity and stability for the degradation of RhB under visible light irradiation. It can be found that after mixing g-C 3 N 4 with WO 3 , the catalytic efficiency and photo stability of the WO 3 microrods were substantially improved.…”