The pH Controlled Excellent Photocatalytic Activity of a Composite

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The pH Controlled Excellent Photocatalytic Activity of a Composite Designed from CuBi-based Metal Organic Oxide and Graphene Fa-Nian Shi, Miao Lu, Yi-Wen Bai, Fang Liang, Xiao-Yi Song, Ge Xu, Xiao-Qiang Fan, Xue-Hua Yu, Hong-Peng You, and Zhen Zhao Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/acs.cgd.8b00490 • Publication Date (Web): 07 Aug 2018 Downloaded from http://pubs.acs.org on August 13, 2018

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Crystal Growth & Design

The pH Controlled Excellent Photocatalytic Activity of a Composite Designed from CuBi-based Metal Organic Oxide and Graphene Fa-Nian Shi,*,† Miao Lu,† Yi-Wen Bai,† Fang Liang,† Xiao-Yi Song,† Ge Xu,*,† Xiao-Qiang Fan,‡ Xue-Hua Yu,‡ Hong-Peng You,*,§ and Zhen Zhao*,‡ †

School of Science, Shenyang University of Technology, No. 111, Shenliao West Road,

Economic & Technological Development Zone, 110870, Shenyang, P. R.China ‡

Institute of Catalysis for Energy and Environment,Shenyang Normal University, 110034,

Shenyang, P. R.China §

State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied

Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China

KEYWORDS: Composite photocatalyst, Metal organic oxide/graphene, Copper, Bismuth, Rhodamine B

ACS Paragon Plus Environment

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ABSTRACT: A CuBi-bearing mixed metal organic oxide (MOO) combined with graphene as a heterogeneous composite photocatalyst (CuBi-MOO/Gr) has been synthesized via one pot hydrothermal method. Raman spectroscopydata and TEM images confirm the presence of graphene on the surfaces of the crystalline particles of the as-prepared CuBi-MOO/Gr sample. The energy gap of CuBi-MOO/Gr is about 2.67 eV which means that the composite can absorb light both in visible and UV regions. The photocatalytic study of Rhodamine B (RhB) with varied pH values (from 1.82 to 11.50) using CuBi-MOO/Gr and CuBi-MOO as photocatalyst,respectively, is performed and compared indicating the high structural stability of the as-prepared CuBi-MOO/Gr composite. The unique photocatalytic results show that within 10 minutes almost 100% of degradation of RhBin aqueous solution is achieved at pH = 1.82 under visible light irradiation and the composite is reusable with high stability. One very interesting phenomenon is, at pH of 1.82, RhB is observed significantly to be adsorbed by simply adding CuBi-MOO/Gr without any light irradiation indicating CuBi-MOO/Gr is a better adsorbent for RhB than CuBi-MOO under dark acidic conditions.

1. INTRODUCTION Photocatalysis is now regarded as one of the best ways to treat problems of environmental pollution, especially some organic pollutants in water because it is an environment-friendly technology which has attracted much attention all over the world. TiO2 is always the most promising photocatalyst since A. Fujishima and K. Honda found water splitting on titanium dioxide photoanodes in 1972.1 TiO2 is a rare material with merits such as low cost, chemical stability and high efficiency.2-4 However, TiO2 has some defects which limit its applications in


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photocatalysis.5-7 For instance, its band gap energy is about 3.2eV, which means that TiO2 could only be inspired under ultraviolet light, thus it has a low efficiency in utilization of the solar energy. Besides TiO2, various bismuth oxides are welcomed as excellent photocatalysts too.8-11 As unique semiconductors, among the merits of bismuth oxides, the most compelling one should be its effective activity under visible light. For example, Bi2O3 has the band gap of 2.3eV which can effectively take advantage of both ultraviolet and visible sunlight for photocatalysis.12In addition, researcheson other composite materials have expanded to applications in fields such as photoelectrochemical sensors and biosensors etc.13-17 Recently, chemists reported that some coordination polymers (CPs) could be used as photocatalysts and most of which performed effectively photocatalytic activities.18CPs are composed of metal centres as nodes and organic ligands as rods to build infinite one dimensional chain, two dimensional network or three dimensional framework (MOF), respectively, connected via coordination bonds of moderate strength.18 MOFs (or porous CPs) have many merits such as large surface areas, homogeneous active sites and tunable functionality, which make them useful in numerous areas, including gas storage, separation, sensing and catalysis, as well as several other interesting applications.19-21 Till now, CPs used as photocatalysts are still fresh.22-24 Design of various CPs composites is an effective strategy to improve the photocatalytic properties of CPsmaterials.25 Though many CPs (including MOFs) have been investigated for their photocatalytic activities, Bi-based CPs are still relatively new members in this field, in particular, those called metal organic oxides (MOO) which are more similar to inorganic metal oxides from the point-view of infinite metal-oxygen (M-O-M-O) connectivity.26-28


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Herein, we report a CuBi-MOO with the molecular formula of Bi3O2Cu(OH)(pdc)2) which was synthesized already but with no investigation in photocatalysis.21 In order to reach a better level of the property we purposely modified it with graphene to obtain a composite (CuBiMOO/Gr) which showed the degradation of RhB almost completely (>98%) within 10 minutes and excellent stability itself at the pH value of 1.82 under the simulated solar light. To our best knowledge, such an efficient photocatalyst for visible light driven degradation of RhB has not been reported to date.29-35

2. RESULTS AND DISCUSSION 2.1. Preparation of CuBi-MOO and CuBi-MOO/Gr. The preparation method of CuBiMOO (Bi3O2Cu(OH)(pdc)2) is similar to the literature,26 while the composite CuBi-MOO/Gr was prepared via one step hydrothermal method by directly mixing quantified copper(II) hydroxide carbonate, bismuth (III) nitrate pentahydrates, 4,4’-bipyridine, 3,5-pyrazoledicarboxylic acid monohydrate and graphene in a molar ratio of 1:2:1:2:0.1, and then heated at 200oC for 3 days (see the details in the experimental section). The ultrasonic were used to remove extra black graphene powders which retained the tiny grains having some interfacial interaction with CuBiMOO particles. 2.2. Optical Microscope Data of CuBi-MOO and CuBi-MOO/Gr. The crystal particles of the two samples show light blue for CuBi-MOO and dark blue for CuBi-MOO/Gr (Figure 1). The darker colour of CuBi-MOO/Gr is attributed to the existence of graphene on the particles (Figure 1a,b). It is clearly observed that CuBi-MOO have the uniformed morphology of rectangular blocks with a very smooth surface and a sharp fringe, in spite of some aggregated.Although some particle shapes of the CuBi-MOO/Gr composite look different


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besides rectangle (Figure 1b), the single crystal diffraction data illustrate the same structure with the similar unit cell parameters (Table 1) which roughly confirm the phase purity. The area and point EDS analyses (Figure S1) on different particles suggest the coexistence of Bi and Cu in the frameworks. Carbon is qualitatively confirmed to be presence in the particles but it cannot be distinguished from both organic ligand and graphene via EDS data.

Figure 1. Comparison of the data between the two samples to show the presence of Gr in CuBi-MOO/Gr composite.(a): Optical microscope image of CuBi-MOO and (b): CuBiMOO/Gr; (c): Raman spectra of commercial Gr (black), as-synthesized CuBi-MOO (red) and as-synthesized CuBi-MOO/Gr (blue); (d): TEM image illustrates the ultrathin Gr layers folded on the surfaces of the composite particles.


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Table 1. Unit cell parameters for CuBi-MOO and CuBi-MOO/Gr (Figure 1b) CuBi-MOO/Gr

CuBi-MOO/Gr

CuBi-MOO/Gr

(a, rectangle)

(b, parallelogram)

(c, hexagon)

CuBi-MOO a (Å)

7.09

7.06

7.05

7.06

b (Å)

9.86

9.88

9.86

9.80

c (Å)

12.13

12.09

12.07

12.10

α (°)

71.13

71.04

71.13

70.90

β (°)

83.79

83.41

83.18

83.24

γ (°)

86.87

86.81

86.55

86.9

2.3. TEM and Raman Spectra Analyses of CuBi-MOO/Gr. In order to confirm the formation of the composite, Raman spectra were measured for the commercial graphene, CuBiMOO and CuBi-MOO/Gr samples (Figure 1c), respectively, which truly displayed the feature peaks of graphene in the composite (1567cm-1 and 1334cm-1).36-37 The disappearance of the typical peak at 2686cm-1 may be due to certain interfacial interactions among graphene and CuBi-MOO particles in the composite. The similar Raman spectra between the two samples imply that both have the identical structure, which is consistent to the single crystal X-ray diffraction data (Table 1). TEM image (Figure 1d) of the CuBi-MOO/Gr sample demonstrates clearly the thin folded layers of graphene on the surfaces of the particles that rationally suggest the presence of graphene in the composite. Powder XRD patterns (Figure2a) illustrate the identical phase between the as-synthesized CuBi-MOO and the as-synthesized CuBi-MOO/Gr when compared with the simulated one from the single crystal structure. The structure is 3-dimensional (Figure 2b) and very dense (d = 4.359 gcm-3) as well as with inorganic connectivity,26 which is why we called the compound metal


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organic oxide (MOO). The XRD pattern of CuBi-MOO/Gr was also compared with graphene (not shown), while less content of graphene in the composite might be the reason why no peak appeared around 26.4o(the characteristic peak of graphene) in the XRD pattern of CuBiMOO/Gr. The FT-IR spectra (Figure S2) show there are almost no difference between them suggesting the similar chemical environments around chemical functional groups, which also imply that the CuBi-MOO/Gr composite has the same structure as the as-synthesized CuBiMOO consistent to the single crystal X-ray diffraction data.

Figure 2. The structural data of the two samples.(a): Powder XRD patterns of CuBiMOO (blue), CuBi-MOO/Gr (red) and the simulated one from the single crystal


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diffraction data (black, CuBi-MOO); (b): The super cell (2x2x2) framework of CuBiMOO displaying very dense structure with extended inorganic connectivity.

Figure 3. (a): The UV-Visible absorption spectra of CuBi-MOO and (b): Tauc plot for CuBi-MOO; (c): The UV-Visible absorption spectra of CuBi-MOO/Gr and (d): Tauc plot for CuBi-MOO/Gr. 2.4. UV-Visible Absorption Spectra Analyses. UV-Visible absorption spectra of the two materials were performed under ambient conditions. We analyzed the light absorption performance of CuBi-MOO and CuBi-MOO/Gr (Figure 3a,c) and found that both as photocatalysts obviously absorb ultraviolet light, part of visible light with wavelength ranging from 500 to 700nm and part of near infrared in the region of 700-850nm, respectively. The


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differences exist only in absorption intensity: CuBi-MOO/Gr shows higher absorption than CuBi-MOO in visible and near infrared region and similar intensity in ultraviolet region. The band gaps(Figure 3b,d) of the two materials calculated from the Tauc plot suggest that CuBiMOO/Gr(2.67eV) may perform better in photocatalysis than CuBi-MOO (2.77eV). The enhancement in photo-response may lead to a better photocatalytic activity that attracts us to study their photocatalytic behaviours.


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Figure 4. UV-Visible absorption spectra of a RhB solution degraded by (a): CuBi-MOO and (b): CuBi-MOO/Gr; (c): the degradation of RhB aqueous solution in different pH values with CuBi-MOO as photocatalyst; (d):the degradation of RhB aqueous solution in different pH with CuBi-MOO/Gr as photocatalyst; (e): the degradation of RhB aqueous solution (pH1.82) with CuBi-MOO and CuBi-MOO/Gr as photocatalysts and a blank experiment. The photocatalytic activities of the samples were studied by the degradation of RhB in aqueous solution under visible light irradiation. About 8.11% and 18.43% of RhB were decomposed in 5.5 hours, respectively(Figure 4a,b), both of which did not show interesting photocatalytic performance. Then we inspected in different pH (Figure 4c) with CuBi-MOO as photocatalyst the degradation of RhB aqueous solution since pH is a very important factor.Indeed it was found the following very attractive decomposition result. When the pH value is about 1.82, the degradation effects of both CuBi-MOO and CuBi-MOO/Gr behave amazingly excellent (Figure 4c,d,e) and the latter composite (about 10 minutes used under irradiation to completely decompose RhB) is much better than the former CuBi-MOO (more than 50 minutes used under irradiation to reach the same level for decomposition of RhB). As a comparison, the degradation of RhB by the composite have been measured at different pH values (Figure 4d), which showed much higher adsorption (>50% in pH 3.18 and ~70% in pH 2.21 for 30min.) and higher photocatalysis (>85% in pH 3.18 and ~95% in pH 2.21 for the subsequent 90min.) of RhBthan CuBi-MOO at the similar pH values suggesting that at slightly higher pH (~3), the composite shows effective removal of RhB from water. Powder XRD patterns (Figure 5) show that at the different pH from 1.82 to 11.50 the structures are maintained the same as the one before photocatalysis suggesting the high stability of the composite photocatalyst in the wide pH


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range.This composite can survive from such high acidic condition due to the good structural stability resulted from many strong metal-oxygen coordination bonds (see reference 26 and its supporting information) which will take large energy and long time to break them. Although we do not know what really happened to accelerate the removal of RhB in acidic solution, here a sound reasonable explanation would be given as follows: Under highly acidic condition (pH = 1.82), RhB molecules were activated but still stable (Figure 4e, the blank experiment). When the external stimulus (Figures 4c,4d,4e visible light irradiation and/or addition of a photocatalyst) occurred to the RhB molecules which was resulted in becoming unstable and the decomposition of RhB might take place. During the 30 minutes period of the dark reaction at pH 1.82 it is supposed that both photocatalyst and RhB become more active than those at neutral conditions (ca. pH 6.5). The particle surfaces of CuBi-MOO/Gr composite were effectively modified with H+ to absorb more quantity of RhB and photocatalytically removed more amount of RhB under visible light. CuBi-MOO and its composite were rationally deduced to act as a catalyst to provide a convenient way for the effective decomposition of RhB leading to the rapid removal of large quantity of RhB occurred in dark conditions. In our experimental conditions, the best decomposition factors are the addition of CuBi-MOO/Gr composite as a photocatalyst plus visible light irradiation, which was convinced by the following experimental data in Figure 6.


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Figure 5. The comparison of powder XRD patterns of CuBi-MOO before and after photocatalytic degradation of RhB in different pH values.


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Figure 6. (a): UV-Visible absorption spectra of a RhB solution with pH=1.82 degraded by CuBi-MOO/Gr; (b): 2 cycles of degradation of RhB under visible light without dark reaction and (c): XRD patterns of CuBi-MOO/Gr before and after photocatalyses.


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The composite CuBi-MOO/Gr as photocatalyst was used to decompose RhB (Figure 6a) under the pH of 1.82 and the degradation rate of CuBi-MOO/Gr could reach almost 100% in 35 minutes (30 minutes of dark reaction and 5 minutes of light reaction). This great improvement can be partly attributed to the slightly bigger surface area of CuBi-MOO/Gr (1.32m2/g) than CuBi-MOO (0.73m2/g). Whereas the higher photoresponse range of CuBi-MOO/Gr should be the major reason. It is important to note that 83.04% of degradation rate reached in 30 minutes of dark reaction should be resulted by the excellent adsorption performance of graphene and also somewhat catalysis of graphene in this case although the catalytic mechanism is unknown. In order to just study the composite’s photocatalytic activity and effects, the dark reaction was omitted and the system was directly irradiated under visible light. Within only 10 minutes of the photocatalytic process, the degradation rate of RhB aqueous solution could reach 98.81% in the first cycle and 97.48% in the second cycle (Figure 6b). All the results indicate that CuBiMOO/Gr performed well as an excellent photocatalyst. No conspicuous differences observed in the xrd patterns of CuBi-MOO/Gr (Figure 6c) indicate that there are no changes in structure and the composite material shows high stability and high activity. As a semiconductor, CuBi-MOO/Gr has a similar mechanism for its photocatalysis (Figure 7) to others.38-39 When it is irradiated by solar energy, the electrons on valence band (VB) will be excited and jump to conduction band (CB), leaving holes on valence band. Photo-induced electrons and holes can move freely on CB and VB, respectively and then make conducting to come true. O2 reacts with e- to form ·O2-, while H2O/OH- react with holes to form ·OH. Both

·O2- and ·OH are very active and strong oxidizers, which could degrade organic chemicals to harmless small molecules. It is worth noting that recombination of electron-hole pairs is an


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important factor hindering the photocatalytic activity for most photocatalysts and many methods have been employed to try to overcome this problem such as doping, combination and so on. In this communication, the existence of graphene in CuBi-MOO/Gr composite is rationally considered to promote the separation of electron-hole pairs because of its strong electrical conductivity.40-41 A series of experiments (see the details of the experiment) have been conducted to further understand the mechanism of the degradation of RhB. To our knowledge,·OH, ·O2and holes are all active species during the photocatalytic degradation of RhB, but we do not know which one plays a main role. Herein, we introduce TBA,42 BZQ43 and EDTA44 as trapping agents of ·OH, ·O2- and holes respectively, then we find all the agents make the degradation rate of RhB decreased obviously, which indicates that ·OH, ·O2- and holes are all active species and the effect of degradation in turns is ·O2-> holes >·OH (Figure 8). The excellent result may be caused by the strong electrical conductivity of graphene.

Figure 7. Possible mechanism for the degradation of RhB by CuBi-MOO/Gr.


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Figure 8. Carriers capture experiment during the CuBi-MOO/Gr photocatalytic degradation of RhB which demonstrate that the degradation rate of RhB are obviously decreased which indicate that ·OH，·O2- and holes are all active species and they are in order: ·O2->holes >·OH.

3. CONCLUSIONS In summary, both CuBi-MOO and the composite CuBi-MOO/Gr are hydrothermally prepared for new photocatalysts with the excellent performance in degradation of RhB aqueous solution under visible light irradiation. In particularly, within 10 minutes, at the pH value of 1.82, the degradation rates of RhB reach almost 100% using CuBi-MOO/Gr composite as photocatalyst due to the addition of graphene resulting in the enhancement of absorption of visible light by the composite CuBi-MOO/Gr. The structure of CuBi-MOO/Gr remains after 2 cycles of the photodegradation reactions, which shows high stability of the composite material. This excellent


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composite photocatalyst is with great potential for being used to the degradation of RhBfrom waste water under the visible light. In addition, CuBi-MOO is stable in a wide pH range from 1.82 to 11.50 suggesting that as photocatalysts CuBi-MOO and its composite CuBi-MOO/Gr could be qualified under different acidic and basic conditions. In comparison with TiO2-based photocatalysts, the following two advantages of our photocatalystsis worth to be noted: 1st, most TiO2-based photocatalysts used only UV light, however, here we used visible light and achieved very good results; 2nd, In the high acidic conditions (pH 1.82), CuBi-MOO/Gr photocatalyst can fast remove RhB almost 100% within 10 min under irradiation of visible light and the composite photocatalyst is reusable. One interesting phenomenon is at low pH range from 3.18 to 1.82, RhB was observed to be adsorbed in a good quantity by simply adding CuBi-MOO/Gr composite without light irradiation indicating CuBi-MOO/Gr under acidic conditionmight catalyze RhB to be decomposed even without light illumination although currently the catalytic mechanism is still unknown. The use of this composite as a photocatalyst to perform the photo-degradation of other organic dye waste water is underway.

4. EXPERIMENTAL SECTION 4.1. Materials. All reagents are commercially available and were used without further purification. Copper(II) hydroxide carbonate (CuCO3·Cu(OH)2,AR, Damao chemical reagent factory in Tianjin); bismuth (III) nitrate pentahydrates (Bi(NO3)3·5H2O, AR, Damao chemical reagent factory in Tianjin); 4,4’-bipyridine (4,4’-bpy, C10H8N2, AR, Damao chemical reagent factory in Tianjin); 3,5-pyrazoledicarboxylic acid monohydrate (H3pdc, C5H5N2O4·H2O, ≥ 98%, Alfa Aesar); and graphene (nanoplatelets aggregates, submicron particles, S.A. 500 m2/g, Alfa


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Aesar); Rhodamine B (AR, Damaochemical reagent factory in Tianjin);HCl (AR, Damaochemical reagent factory in Tianjin);NaOH (AR, Damaochemical reagent factory in Tianjin). 4.2. Preparation of CuBi-MOO. 0.0317g of CuCO3·Cu(OH)2, 0.1272g of Bi(NO3)3·5H2O, 0.0413g of 4,4’-bpy and 0.0622g of H3pdc were added into 10g of distilled H2O under magnetic stirring until getting good homogeneity. The mixture was transferred into a 25mL Teflon-lined autoclave and heated at 200oC in an oven for 3 days. After natural cooling to room temperature, a large amount of blue crystals were harvested and washed with distilled water (3 x 50mL), filtered and dried under ambient conditions (yield: 0.0442g, ~48.3% based on Bi(NO3)3·5H2O). 4.3. Preparation of CuBi-MOO/Gr. The composite was prepared with graphene (0.0200g) and other reagents in the similar masses to the preparation forCuBi-MOO. All reagents were added into 10g of distilled H2O with 30 minutes of ultrasonic processing and then transferred the mixture into a 25mL Teflon-lined autoclave and kept at 200oC in an oven for 3 days. After natural cooling to room temperature, a large amount of dark-blue crystals were harvested and washed with distilled water, filtered and dried under ambient conditions. 4.4. General Instruments.The unit cell parameters indexation of single-crystal particles were performed at room temperature on a Rigaku Supernova diffractometer (50 kV, 0.8mA, Mo-Kα graphite monochromated radiation, λ = 0.71073Å).The phases of the 2 products were identified by using powder X-ray diffraction (PXRD) on a MiniFlex600 diffractometer (40 kV, 15 mA) with Cu Kα (λ = 0.15405 Å) in a 2theta range from 5 to 50 degree. The morphologies, contents and elemental distribution of the samples were observed using a scanning electronic microscope (SEM) and an energy dispersive spectrometer (EDS) of Phenom proX with CeB6 filament and


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working at 10 kV. the SEM samples were coated by gold on a SBC-12 ion sputtering instrument.The TEM images were performed on a FEI Tecnai G2F30 transmission electronic microscope. The colour, morphology and purity of the samples were qualitatively observed under a Nikon C-PSN optical microscope. Laser Raman spectrometer (LabRAM HR Evolution, the laser wavelength: 532nm; the power: 5%; the scan time: 3 times per 20 seconds) and infrared spectrometer (SHIMADZU, IRPrestige-21/FTIR-8400S, KBr pellets) were also used in this study.The UV-Visible diffuse reflection spectra were taken on a TU-1950UV-Vis spectrometer equipped with an integrating sphere. The UV-Visible diffuse reflection data was conversed to the following Kubelka-Munk function (F(R)). Tauc plots take hν as abscissa and (F(R)·hν)1/2as ordinate.

hν =

F ( R) =

1240

λ (1 − R) 2 2R

4.5. Photocatalytic Experiments.The photocatalytic activities of the samples were studied by the degradation of RhB in aqueous solution. 100mL of the RhB aqueous solution with a concentration of 5mg/L was mixed with 100mg of the samples and was then exposed to illumination of visible light. Before turning on the lamp, the suspension containing RhB and the photocatalyst was magnetically stirred in dark for 30 minutes to reach an adsorption-desorption equilibrium. 3mL of suspension were removed from the reactor and centrifuged immediately to separate any suspended solid. Then turning on the lamp and repeating the steps above every 60 minutes until the absorbance close to zero or the color of the solution doesn’t change any more.


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The absorbance of the transparent solution was analyzed with a UV-Vis spectrometer (PERSEE, TU-1950).

ACKNOWLEDGMENTS Authors acknowledge the project 21571132 supported by the NSFC. This work was also supported by the Open Fund (RERU2017005) of National Key Laboratory of Rare Earth Resources Utilization, the key project (LZGD2017002) of Department of Education of Liaoning Province and scientific research project (LGD2016014) of Liaoning Province Education Department.

SUPPORTING INFORMATION The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.cgd.xxxxx. SEM images and EDS spectra of CuBi-MOO/Gr composite as well as FTIR spectra of CuBi-MOO and CuBi-MOO/Gr.

REFERENCES (1) Fujishima, A.; Honda, K., Electrochemical photolysis of water at a semiconductor electrode.Nature1972,238,37-38. (2) Kou, J.; Lu, C.; Wang, J.; Chen, Y.; Xu, Z.; Varma, R.S.,Selectivityenhancement in heterogeneous photocatalytic transformations.Chem. Rev2017,117, 1445−1514. (3) Guo, Q.; Zhou, C.; Ma, Z.; Ren, Z.; Fan, H.; Yang, X., Elementary photocatalytic chemistry on TiO2 surfaces.Chem. Soc. Rev2016, 45, 3701-3730.


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(4) Varshney, G.;Kanel, S.R.;Kempisty, D.; Varshney, V.; Agrawal, A.;Sahle-Demessie, E.; Varma, R.S.;Nadagouda, M.N.,Nanoscale TiO2 films and their application in remediation of organic pollutants.Coordin. Chem. Rev2016, 306, 43-64. (5) Hou, H.L.; Wang, L.; Gao, F.M.; Wei, G.D.; Zheng, J.J.;Tang, B.; Yang, W.Y.,Hierarchically porous TiO2/SiO2 fibers with enhanced photocatalytic activity.RSC Adv2014, 4, 1993919944. (6) Wei, N.; Cui, H.; Song, Q.; Zhang, L.; Song, X.; Wang, K.; Zhang, Y.; Li, J.; Wen, J.; Tian, J.,Ag2O nanoparticle/TiO2 nanobelt heterostructures with remarkable photo-response and photocatalytic properties under UV, visible and near-infrared irradiation. Appl. Catal. BEnviron2016, 198, 83-90. (7) Tian, J.; Hao, P.; Wei, N.; Cui, H.; Liu, H., 3D Bi2MoO6 Nanosheet/TiO2 Nanobelt Heterostructure:

Enhanced

Photocatalytic

Activities

and

Photoelectochemistry

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TOC-Synopsis page For Table of Contents Use Only

The pH Controlled Excellent Photocatalytic Activity of a Composite Designed from CuBi-based Metal Organic Oxide and Graphene

Fa-Nian Shi, Miao Lu, Yi-Wen Bai, Fang Liang, Xiao-Yi Song, Ge Xu, Xiao-Qiang Fan, XueHua Yu, Hong-Peng You, and Zhen Zhao

TOC graphic:


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Synopsis: A CuBi-bearing mixed metal organic oxide (MOO) combined with graphene as a heterogeneous composite photocatalyst (CuBi-MOO/Gr) has been synthesized via one pot hydrothermal method. The photocatalytic study of Rhodamine B (RhB) with varied pH values (from 1.82 to 11.50) were carried out using CuBi-MOO/Gr and CuBi-MOO as photocatalyst, respectively. At pH 1.82, CuBi-MOO/Gr shows excellent removal of RhB within 10 min under visible light irradiation, which is promising for future use to clean off organic pollutants from water.


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The pH Controlled Excellent Photocatalytic Activity of a Composite

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