Graphene Oxide Photocatalysts Research Articles

Persulfate assisted photocatalytic and antibacterial activity of TiO2–CuO coupled with graphene oxide and reduced graphene oxide

Photocatalysts of TiO2–CuO coupled with 30% graphene oxide (GO) were hydrothermally fabricated, which varied the TiO2 to CuO weight ratios to 1:4, 1:2, 1:1, 2:1 and 4:1 and reduced to form TiO2–CuO/reduced graphene oxide (rGO) photocatalysts. They were characterized using XRD, TEM, SEM, XPS, Raman, and DRS technologies. TiO2–CuO composites and TiO2–CuO/GO degrade methylene blue when persulfate ions are present. Persulfate concentration ranged from 1, 2, 4 to 8 mmol/dm−3 in which the highest activity of 4.4 × 10–2 and 7.35 × 10–2 min−1 was obtained with 4 mmol/dm−3 for TiO2–CuO (1:4) and TiO2–CuO/GO (1:1), respectively. The presence of EDTA and isopropyl alcohol reduced the photodegradation. TiO2–CuO coupled with rGO coagulates methylene blue in the presence of persulfate ions and such coagulation is independent of light. The catalyst dosage and the concentration of the dye were varied for the best-performing samples. The antibacterial activity of the synthesized samples was evaluated against the growth of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumonia. Ti:Cu (1:2)-GO and Ti:Cu (1:4)-GO had the highest antibacterial activity against K. pneumoniae (16.08 ± 0.14 mm), P. aeruginosa (22.33 ± 0.58 mm), E. coli (16.17 ± 0.29 mm) and S. aureus (16.08 ± 0.88).

Strategic decolorization of rose bengal in an aqueous environment using a zinc oxide-loaded reduced graphene oxide photocatalyst

The environmental and health hazards posed by synthetic organic dyes, such as Rose Bengal, have spurred significant concern in recent years. Herein, a novel zinc oxide/reduced graphene oxide (ZnO/rGO)-based photocatalyst is developed and used for the efficient decolorization of RB dye in aqueous solutions. The as-synthesized nanostructured material is characterized using advanced techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) mapping to elucidate its crystalline structure, morphology, and elemental composition. The XRD pattern confirmed the wurtzite crystalline phase structure with an average size of 67.8 nm, while SEM imaging verified the successful incorporation of ZnO nanoparticles into the rGO matrix. Further, the as-prepared material was used as a photocatalyst, which demonstrated remarkable performance in RB dye decolorization, achieving ≥96.1 % degradation within just 5 min at a minimal catalyst dosage of 8.0 mg. Moreover, kinetic studies revealed that the decolorization process followed a pseudo-second-order reaction mechanism, further enhancing the understanding of the catalytic behavior. It is more interesting that the catalyst exhibited exceptional reusability for up to seven cycles with only a decrease in catalyst efficiency from 96.1 % to 77.5 %, underscoring its practical viability and sustainability. The significance of this work lies in its contribution to addressing the environmental challenges associated with synthetic dyes, particularly rose bengal, by offering an efficient and reliable photocatalytic solution. The demonstrated efficacy of the ZnO/rGO photocatalyst not only showcases its potential for large-scale rose bengal dye degradation but also suggests broader applicability for the treatment of other synthetic dye pollutants.

Ni7S6 decorated g-C3N4/graphene oxide composites for enhanced visible light photocatalytic hydrogen evolution

Rationally designing high-efficient g-C3N4 based photocatalysts still remains a big challenge. Herein, Ni7S6 decorated K-doped g-C3N4/graphene oxide photocatalyst was synthesized. Interestingly, amorphous conductive carbon black and urea are simultaneously transferred to graphene oxide and K-doped g-C3N4, which achieves in-situ coupled K-g-C3N4/graphene oxide composite. The in-situ fabricated graphene oxide acts as a charge transfer substrate for the rapid photocarriers migration. Ni7S6 forms Schottky heterojunction with K-g-C3N4 photocatalyst, promoting photocarriers separation. The Ni7S6/K-g-C3N4/graphene oxide composite achieves a visible light hydrogen production rate of 487.59 μmol·g−1·h−1, which is about 7.5 times higher than that of K-g-C3N4 (65.4 μmol·g−1·h−1). This work provides a novel strategy for preparing high-efficient g-C3N4 based photocatalysts.

Fabrication of CuO derived reduced graphene oxide photocatalyst for the strategic decolorization of Congo red from an aqueous environment

Herein, we designed a novel reduced graphene oxide functionalized copper oxide (rGO-CuO) nanocomposite material through simple method. The synthesized rGO-CuO nanocomposite is rigorously characterized via advanced techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). These characterizations reveal crucial insights into the nanocomposite crystalline attributes, phase purity, morphological characteristics, and elemental composition, collectively confirming its successful fabrication. Furthermore, the synthesized nanocomposite is subsequently used for the proficient decolorization of Congo Red (CR) dye within an aqueous medium employing a careful optimization of experimental variables including the concentration of sodium borohydride (NaBH4), solar irradiation, and catalytic dosage. The developed photocatalytic achieved 98.7 % degradation of CR dye at a minimal catalyst dosage of 2.4 mg in a 5-min reaction time. Notably, the nanocomposite exhibits reusability for up to five cycles with 88 % efficiency, underscoring the durability and reliability of the rGO-CuO photocatalyst. Moreover, the kinetic study evaluation demonstrated that the decolorization of dye at surface of the catalyst follows pseudo first order reaction. The rGO-CuO nanocomposite could be a suitable candidate for the rapid photocatalytic degradation of CR dye not only at low level but also at industrial scale.

Solar Light-Responsive ZnS/Reduced Graphene Oxide Photocatalysts for Enhanced Hydrogen Evolution

Solar Light-Responsive ZnS/Reduced Graphene Oxide Photocatalysts for Enhanced Hydrogen Evolution

Cadmium sulfide composite reduced graphene oxide for selective oxidation of 5-hydroxymethylfurfural to 2.5-diformylfurans

In this study, the Cadmium sulfide composite reduced graphene oxide photocatalyst (CdS/xrGO) was successfully synthesized to enhance the conversion of photocatalytic oxidation of 5-hydroxymethylfurfural (HMF). The conversion of 5-hydroxymethylfurfural and the yield of 2.5-diformylfurans (DFF) were 71.18 % and 69.72 %, respectively under optimum conditions, and the selectivity of DFF was significantly higher of about 97.94 %. Compared with CdS as a catalyst, HMF conversion and the DFF yield were roughly double. The excellent photocatalytic performance can be found through various characterization results because specific surface area of rGO is larger which provides many numbers of reaction sites for the reaction, reducing the clustering of CdS and allowing better contact between the photocatalyst and the substrate. Meanwhile, photogenerated electrons were easily transferred to the surface of rGO, which results in improving the separation potential of photogenerated carriers inhibited its complexation and resulting in enhanced photocatalytic performance.

Plant-based synthesis of TiO2 – rGO nanocomposite for the efficient photocatalytic degradation of an emerging contaminant: Experimental and theoretical investigations

The need to develop sustainable and efficient photocatalysts for the degradation of contaminants of emerging concern has gained considerable attention. In this study, plant-based titanium dioxide-reduced graphene oxide (TiO2-rGO) photocatalyst was synthesized by a hydrothermal method using Azadirachta indica (AI) leaf extract. Morphological and chemical properties of the AI-TiO2-rGO photocatalyst were evaluated in detail. The clusters of AI-TiO2 wrapped in AI-rGO were identified with TEM analysis, and from the XRD, the purity of AI-TiO2-rGO was confirmed. The low band gap (2.80 eV) of AI-TiO2-rGO made it a suitable photocatalyst under visible light. The X-ray photoelectron spectroscopy (XPS) results indicated the establishment of strong Ti-O-C chemical linkage within the AI-TiO2-rGO photocatalyst. The efficiency of AI-TiO2-rGO was assessed for the degradation of carbamazepine (CBZ) under UV-A irradiation (94.28%) and visible light (59.97%) in a batch photocatalytic reactor for 60 min. The optimized conditions such as AI-TiO2-rGO dosage (50 mg/L), initial CBZ concentration (4.5 mg/L), and light source (UV-A (60 W)), were validated with response surface methodology (RSM). The mechanism of degradation of CBZ by AI-TiO2-rGO was explained with the identification of intermediate compounds, and three plausible CBZ degradation pathways were proposed. The reusability study suggested that the AI-TiO2-rGO photocatalyst could be effectively used for 8 cycles. The evaluation of toxicity of treated water with E.Coli growth curve (reduction in Iind to 30.12% (UV) and 27.65% (visible)) signified that the treated water was less toxic. The comparison of AI-TiO2-rGO with chemically synthesized TiO2-rGO indicated that even though AI-TiO2-rGO exhibited a slightly higher band gap (2.80 eV), it can be the better alternative for the photocatalysts synthesized by chemical route. The economic analysis of the overall process proved that the application of AI-TiO2-rGO was more cost-effective and sustainable than the conventional TiO2 photocatalyst. Overall, the study provides valuable insight into synthesizing recyclable plant-based photocatalysts to degrade recalcitrant emerging contaminants in the water.

Synthesis of Bi-Metallic-Sulphides/MOF-5@graphene Oxide Nanocomposites for the Removal of Hazardous Moxifloxacin

The development of new and advanced materials for various environmental and energy applications is a prerequisite for the future. In this research, the removal of hazardous moxifloxacin (MOX) is accomplished by synthesizing new hybrids of MOF-5 i.e., Ni/Mo.S2/MOF-5/GO, Ni.S2/MOF-5/GO, Mo.S2/MOF-5/GO, and Ni/Mo.S2/MOF-5 nanocomposites by using a metal-organic framework (MOF-5) and graphene oxide (GO) as a precursor. The introduction of NixMoxS2 facilitates the unique interfacial charge transfer at the heterojunction, demonstrating a significant improvement in the separation effectiveness of the photochemical electron-hole pairs. To evaluate equilibrium adsorption capacity, time, pH, and concentration of organic pollutants were used as experimental parameters. The adsorption kinetics data reveals pseudo-first-order (R2 = 0.965) kinetics when Ni/Mo.S2/MOF-5/GO photocatalyst was irradiated under light for 90 min against MOX degradation. This led to a narrow energy band gap (2.06 eV in Ni/Mo.S2/MOF-5/GO, compared to 2.30 eV in Ni/Mo.S2/MOF-5), as well as excellent photocatalytic activity in the photodegradation of moxifloxacin (MOX), listed in order: Ni/Mo.S2/MOF-5/GO (95%) > Ni.S2/MOF-5/GO (93%) > Mo.S2/MOF5/GO (90%) > Ni/Mo.S2/MOF-5 (86%) in concentrations up to 2.0 mgL−1, caused by the production of superoxide (O2•−) and hydroxide (OH•) radicals, which encouraged the effective photocatalytic activities of the heterostructure. After five successive tests demonstrating its excellent mechanical stability, the impressive recyclability results for the Ni/Mo.S2/MOF-5/GO revealed only a tiny variation in efficiency from 95% (for the first three runs) to 93% (in the fourth run) and 90% (in the fifth run). These findings show that the heterostructure of Ni/Mo.S2/MOF-5/GO is an effective heterojunction photocatalyst for the quick elimination of moxifloxacin (MOX) from aqueous media.

An efficient visible light driven photocatalyst based on CuFe2O4/rGO nanocomposites for effective degradation of methylene blue dye

The pollution issue is getting worse at the same time that industry is growing. One of the toxic ingredients of these industrial effluents is the organic dyes. In this research, the efficiency of organic dye degradation over as-prepared copper ferrite (CuFe2O4) and the annealed copper ferrite (600ºC and 800ºC) nanoparticles loaded on the reduced graphene oxide (rGO) photocatalyst was investigated by hydrothermal method. The synthesized particles were characterized by XRD, FT-IR, RAMAN, FESEM, HRTEM, XPS, BET, UV-DRS and VSM. XRD and FESEM analysis were done to investigate structural properties, phase purity and surface morphology of prepared nanoferrite and their nanocomposites. FT-IR spectroscopic analysis was done to investigate functional groups of fabricated material. The FT-IR spectral analysis confirmed the presence of M − O (metal-oxygen) functional groups in the prepared materials. The RAMAN study confirmed the D-band and the G-band of graphene oxide present in the nanocomposites. UV-Vis-DRS study was done to evaluate the optical properties. The surface area and porosity of the nanoferrite and its nanocomposites were concluded by BET. The oxidation states of the constituent ions were confirmed by means of X-ray photoelectron spectroscopy (XPS). An active toxic and stable dye, Methylene Blue (MB) was employed as the target pollutant to evaluate the photocatalytic performance of the prepared nanocomposites. The effect of some parameters, dye concentration, pH and the catalyst concentration were studied. The cycle stability for dye degradation and reusability of the as-prepared catalysts show effective repeating activity up to 92.5% of its initial degradation efficiency of 100% even after four cycles. Moreover, the superparamagnetic property observed from VSM analysis made the nanocomposite recyclable.

Developing a robust photocatalytic and antifouling performance of PVDF membrane using spinel NiFe2O4/GO photocatalyst for efficient industrial dye wastewater treatment

Photocatalytic nanohybrid polyvinylidene fluoride (PVDF) membrane incorporated by nickel ferrite/ graphene oxide (NiFe2O4/GO) photocatalyst is fabricated in this study. To prevent the fast electron/hole recombination rate in NiFe2O4 photocatalyst, GO nanoparticle was added to synthesize the NiFe2O4/GO photocatalyst. The fabricated membranes were tested for industrial dye wastewater treatment, which mainly contained Remazol red RB-133 as the colorant. The modified membranes were synthesized by adapting the non-solvent induced phase separation (NIPS-blending) technique, and their filtration performance were assessed both in the conventional dark filtration condition and under ultraviolet (UV) light exposure. Scanning electron microscopy – Energy dispersive x-ray (SEM-EDX) results reveal that the PVDF/NiFe2O4/GO membrane features a smooth, defect-free surface with a well-built finger-like structure, as well as a well-distributed NiFe2O4/GO distribution on the membrane's surface. Some new hydrophilic groups are recorded on PVDF/NiFe2O4/GO by the Fourier-transform infrared (FTIR) analysis such as -OH, Fe-O, Ni-O, and CO and some crystallite sites of NiFe2O4 and GO, which is helpful to improve the surface hydrophilicity. The permeability, pollutant removal, membrane stability, photodegradation ability, and antifouling activity of the modified membranes in the filtration process under UV light exposure were significantly improved. This membrane removed 83.22% of COD and 92.38% of dye when it was performed under UV light irradiation. The presence of photocatalytic activity on the membranes’ surface also improves the antifouling activity by converting the irreversible fouling into the reversible fouling, hence, the modified membranes have a better performance stability than the other membranes.

Investigating the phenol removal from aqueous media by photocatalytic magnetized graphene oxide nanocomposite

AbstractAs a large and diverse group of secondary metabolites, phenolic compounds are one of the most common chemical pollutants present in water resources. these compounds can have toxic effects on ecosystems and humans. Therefore, their removal from water sources appears to be of great importance. In this study, a magnetic graphene oxide (MGO) photocatalyst was synthesized and used to remove phenol from water. The fabricated GO magnetic nanocomposites were determined by SEM and FTIR techniques. Afterward, these nanoparticles were used to remove phenol from aquatic media considering different operational parameters, including pH of the solution, initial concentration of phenol, contact time, and adsorbent dosage. The results showed that the magnetized GO nanoparticles could remove 90.83% of phenol molecules under the optimal conditions of solution pH = 3.0, initial phenol concentration of 20 mg/L, adsorbent concentration of 300 mg/L, and contact time of 120 min. additionally have compared the results of UV, Fe3O4/GO, and Fe3O4/GO/UV on the removal of phenol under optimum conditions. Accordingly, the phenol removal efficiencies for UV alone, Fe3O4/GO, and Fe3O4/GO/UV were obtained at 4.5, 65.73, and 90.83%, respectively. Based on the findings, the prepared magnetic GO nanoparticles have extended capabilities such as easy and rapid separation from sample and high potential in removing phenolic compounds, so, it can be introduced as an appropriate adsorbent for removal of this pollutant from water and wastewater.

C3N4/reduced graphene oxide photocatalysts loaded with Ag or Ag/Pt for H2 evolution from aqueous solution of triethanolamine

Composites of C3N4/reduced graphene oxide have been used as photocatalysts for triethanolamine photo-reforming with H2 generation in aqueous solution. The rate of H2 production over the Ag loaded best performing photocatalyst reached 525 μmol·h−1·g−1 which increases to ca. 88,000 μmol·h−1·g−1 in the presence also of 1% of Pt. The apparent quantum efficiency (AQE) of the optimal material was ca. 9% by using both visible LED or natural sunlight irradiation.

Colloidal nanomaterials for water quality improvement and monitoring.

Water is the most important resource for all kind forms of live. It is a vital resource distributed unequally across different regions of the globe, with populations already living with water scarcity, a situation that is spreading due to the impact of climate change. The reversal of this tendency and the mitigation of its disastrous consequences is a global challenge posed to Humanity, with the scientific community assuming a major obligation for providing solutions based on scientific knowledge. This article reviews literature concerning the development of nanomaterials for water purification technologies, including collaborative scientific research carried out in our laboratory (nanoLAB@UA) framed by the general activities carried out at the CICECO-Aveiro Institute of Materials. Our research carried out in this specific context has been mainly focused on the synthesis and surface chemical modification of nanomaterials, typically of a colloidal nature, as well as on the evaluation of the relevant properties that arise from the envisaged applications of the materials. As such, the research reviewed here has been guided along three thematic lines: 1) magnetic nanosorbents for water treatment technologies, namely by using biocomposites and graphite-like nanoplatelets; 2) nanocomposites for photocatalysis (e.g., TiO2/Fe3O4 and POM supported graphene oxide photocatalysts; photoactive membranes) and 3) nanostructured substrates for contaminant detection using surface enhanced Raman scattering (SERS), namely polymers loaded with Ag/Au colloids and magneto-plasmonic nanostructures. This research is motivated by the firm believe that these nanomaterials have potential for contributing to the solution of environmental problems and, conversely, will not be part of the problem. Therefore, assessment of the impact of nanoengineered materials on eco-systems is important and research in this area has also been developed by collaborative projects involving experts in nanotoxicity. The above topics are reviewed here by presenting a brief conceptual framework together with illustrative case studies, in some cases with original research results, mainly focusing on the chemistry of the nanomaterials investigated for target applications. Finally, near-future developments in this research area are put in perspective, forecasting realistic solutions for the application of colloidal nanoparticles in water cleaning technologies.

Graphitic carbon nitride engineered α-Fe2O3/rGO heterostructure for visible-light-driven photochemical oxidation of sulfamethoxazole

Rational design of semiconductor photocatalysts is an effective way to achieve efficient visible-light-driven environmental remediation. Herein, a series of graphitic carbon nitride (g-C3N4) engineered hematite (Fe2O3)/reduced graphene oxide (rGO) photocatalysts were synthesised and employed in visible-light-driven photo-Fenton-like degradation of sulfamethoxazole (SMX). The exceptional performance of the optimal photocatalyst (0.4-FerGCN-3) was achieved because of the successful structural integration of g-C3N4/Fe2O3/rGO for efficient separation and migration of photoinduced charge carriers (e−/h+). Photochemical decomposition efficiency was also optimised by analysing the important reaction parameters such as initial catalyst loading, initial H2O2 dosage, pH, and reaction temperature. Detailed studies on the generation of reactive species and degradation intermediates were performed to propose a possible mechanism for SMX degradation. The findings may provide not only a strategy for nanostructure engineering of semiconductor photocatalysts but also insights into the effective remediation of emerging contaminants such as SMX.

A novel Bi2WO6/BiOBr/RGO photocatalyst for enhanced degradation of ciprofloxacin under visible light irradiation: Performance, mechanism and toxicity evaluation

The residual antibiotics in pharmaceutical wastewater have a great impact on the efficiency and stability of wastewater biological treatment process, and prefer to be treated by advanced oxidation process beforehand. In this study, we synthesized a novel Bi2WO6/BiOBr/reduced graphene oxide (RGO) photocatalyst by one-step hydrothermal method and applied it to the photocatalytic oxidation of ciprofloxacin. The characterization results showed that the photocatalyst had a heterojunction structure and a broadening light absorption range. RGO in the composite effectively reduced the band gap of Bi2WO6/BiOBr and promoted the separation of photogenerated charge carriers. Neutral pH condition was favor of the adsorption and degradation of ciprofloxacin by Bi2WO6/BiOBr/RGO, and the ciprofloxacin removal efficiency could be up to 90.7 % with the optimal molar ratio of Bi2WO6 to BiOBr (1:1) and RGO content (5 wt%). In the free radical quenching experiment, superoxide radicals and photogenerated holes were determined to be major contributors for the photocatalytic degradation of ciprofloxacin. Furthermore, 71.3 % of ciprofloxacin could be removed through mineralization during the photocatalysis process, and the residual pollutants did not significantly affect the biological nitrogen removal process.

Highly Active Semi-Ionic C-F Bonds from Fluorine Doped Photoreduced Graphene Oxide Photocatalyst for Removal of Volatile Organic Compounds

Highly Active Semi-Ionic C-F Bonds from Fluorine Doped Photoreduced Graphene Oxide Photocatalyst for Removal of Volatile Organic Compounds

EDTA-2Na assisted facile synthesis of monoclinic bismuth vanadate (m-BiVO4) and m-BiVO4/rGO as a highly efficient visible-light-driven photocatalyst

An efficient facile synthesis method for BiVO4/reduced graphene oxide (BiVO4/rGO) photocatalyst by a one-pot hydrothermal process was first developed. Ethylene diamine tetraacetic acid disodium salt (EDTA-2Na) rather than nitrate was used to provide an acidic environment to prevent the hydrolysis of Bi3+, which could improve the safety of the process. The photocatalytic activities could be remarkably enhanced by loading BiVO4 on rGO. The degradation efficiency for Rhodamine B (rhB) could reach 98.3% in 180 min. This work offered an ideal method for stable, efficient, and recyclable photocatalysts suitable for the visible light range.

Fabrication of Fe/BiOCl/RGO with enhanced photocatalytic degradation of ciprofloxacin under visible light irradiation

The Fe-doped BiOCl/reduced graphene oxide (Fe/BiOCl/RGO) photocatalyst was synthesized for ciprofloxacin (CIP) degradation under visible light irradiation via a facile and controllable solvothermal approach. Fe-doping and RGO incorporated greatly inhibit the agglomeration of BiOCl and significantly enhance the photodegradation activity by facilitating the separation of photogenerated electron-hole pairs, which could almost completely degrade CIP solution in 180 min. Moreover, Fe/BiOCl/RGO reaches the highest rate constant of 0.021 min−1, which is 2.1 and 4.4 times larger than those of Fe/BiOCl and BiOCl, respectively. Besides, Fe/BiOCl/RGO exhibits excellent stability, which can remain ∼90% after five cycling degradation. Photogenerated ·OH and h+ for CIP degradation are confirmed as the main active species through free radical capture experiments. The improved photocatalytic activity of Fe/BiOCl/RGO is attributed to the strong synergistic effect of Fe-doping and RGO addition, which efficiently extends the visible light absorption extent, along with accelerating the separation and conversion of photogenerated electrons and holes, thus promoting the utilization of photocatalysts under visible light irradiation.

Fabrication of BiVO4/ reduced graphene oxide photocatlyst for hexavalent chromium reduction under visible region

Bismuth vanadate (BiVO4) is widely used as a visible light photocatalyst for elimination of organic and inorganic pollutants in aqueous solution. An integration with few layer graphene oxide into BiVO4, significantly enhance the photocatalytic activity in the visible region due to it’s high charge transport and separation. Herein, we have designed BiVO4 on reduced graphene oxide (rGO) photocatalyst synthesised via simple solution phase method. BiVO4 nanocrystals nanoplates were fabricated using bismuth (III) nitrate, ammonium metavanadate with ammonium hydroxide, and polyethylene glycol as a stabilising agent. The resulting photocatalytic catalyst showed an excellent activity towards Cr(VI) removal (as a model inorganic pollutant) under visible light, which is evidenced with photoelectrochemical studies. The photocatalytic performance for Cr(VI) removal rates over BiVO4/rGO showed much higher activity than BiVO4 in visible light. Furthermore, the catalyst efficiency was confirmed through photoelectrochemical, and optoelectronic properties.

Insight into a novel microwave-assisted W doped BiVO4 self-assembled sphere with rich oxygen vacancies oriented on rGO (W-BiVO4-x/rGO) photocatalyst for efficient contaminants removal

A novel W doped BiVO4 with rich oxygen vacancies (OVs) oriented on reduced graphene oxide (rGO) photocatalyst (W-BiVO4-x/rGO) was developed by a simple one-step microwave hydrothermal method for efficient removal of ciprofloxacin (CIP) and chlortetracycline (CTC) under visible light. The synergistic effect of W doping, BiVO4 with OVs, and rGO on the enhancement of photocatalytic activity was clarified from experimental and Density Functional Theory (DFT) calculations results. W doping significantly improved the density of photo-generated charge carriers. The introduction of rGO enlarged the specific surface area, expanded the light absorption range, and promoted the charge transfer of BiVO4. OVs both narrowed the band gap and enhanced the generation of O2−. W doping and OVs both enhanced the interactions between BiVO4 and rGO. The CIP degradation rate constant of W-BiVO4-x/rGO photocatalyst was 1.73, 5.32, 6.43, and 10.70 times higher than those of W-BiVO4/rGO, BiVO4/rGO, W-BiVO4, and BiVO4, respectively. Besides, W-BiVO4-x/rGO photocatalyst prepared by microwave hydrothermal method exhibited higher photocatalytic activity and better combination between materials. This study offers a new strategy to address the problem of antibiotic residues in wastewater.