Evaluating the photocatalytic efficiency of the BiVO4/rGO photocatalyst

Sukon Phanichphant,Auppatham Nakaruk,Kantapat Chansaenpak,Duangdao Channei

doi:10.1038/s41598-019-52589-5

Abstract

The present study reported the preparation of BiVO4 by co-precipitation method. The as-prepared BiVO4 photocatalyst were deposited on rGO sheets to form BiVO4/rGO via the hydrothermal method. The crystalline structure, morphological, optical properties, and surface properties of the synthesized pure BiVO4 compared to BiVO4/rGO composite were studied using X-ray diffraction (XRD), scanning electronmicroscopy (SEM), photoluminescence (PL) spectrophotoscopy, UV–vis spectrophotometer with an integrating sphere, and N2 adsorption-desorption isotherm based on BET theory. The photocatalytic activity of the prepared samples were evaluated by the degradation of MB dye in aqueous medium under visible light irradiation. The result showed that the BiVO4/rGO composite exhibited greater photocatalytic efficiency compared to pure BiVO4 with the photocatalytic degradation efficiency remains stable up to fifth cycle. The improved activity of the BiVO4/rGO composite might be attributed to the high surface area available to adsorb more MB molecules, and efficient charge separation of BiVO4 through π electron on the rGO structure. According to experimental results, the possible photocatalytic mechanism of the BiVO4/rGO composite were determined and the active species hydroxyl radical were reported. Based on photocatalytic activity inhibition in the presence of both h+ (VB) and O2•− (CB) scavengers over the BiVO4 photocatalyst, it can be proposed that the hydroxyl radical generated during the photocatalytic degradation mechanism is mainly responsible by the main active species of h+ and O2•− at VB and CB positions, respectively.

Highlights

The present study reported the preparation of BiVO4 by co-precipitation method
The aim of this study is to synthesize a multifunctional material of BiVO4/reduced graphene oxide (rGO) composite, combined with the photocatalytic activity of BiVO4 coupled with the adsorption and trapping abilities produced from rGO
The typical diffraction peak of rGO near 10.8°38 were not observed in the X-ray diffraction (XRD) pattern of BiVO4/rGO composite due to the fact that the addition of rGO in composite sample could yield the stacking disorder of rGO owing to the intercalating of BiVO4 into stacked rGO layers, which is in agreement with the literature report of Khalid et al.[39]

Summary

Introduction

The present study reported the preparation of BiVO4 by co-precipitation method. The as-prepared BiVO4 photocatalyst were deposited on rGO sheets to form BiVO4/rGO via the hydrothermal method. The possible photocatalytic mechanism of the BiVO4/rGO composite were determined and the active species hydroxyl radical were reported. Among them are some technologies such as adsorption, coagulation, membrane filtration and sedimentation, which can only change organic contaminants from the primary toxic pollutants to secondary pollutants in treatment process rather than degrade those substances completely[3,4,5,6] They are not effective to meet certain criteria requirements or generate non-biodegradable organic pollutants appearing in effluents after a long period of time. The type of semiconductor catalyst plays an important role in the photocatalytic process such as TiO2, CeO2, ZnO, WO3, BiVO4 photocatalyst which are often applied in photocatalytic treatment[10,11,12,13] Among these catalysts, bismuth vanadate (BiVO4) has recently attracted considerable attention due to its high photocatalytic activity under visible-light irradiation and its small band gap of ~2.4 eV14–19. The resulting dispersions were separated by centrifugation, washed with deionized water until the pH became neutral, dried at 70 °C for 24 h, and calcined at 550 °C for 4 h

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