Graphitic carbon nitride nanosheets decorated with CuCr2O4 nanoparticles: Novel photocatalysts with high performances in visible light degradation of water pollutants
Authors: Aziz Habibi-Yangjeh
Anise Akhundi
Journal: Journal of Colloid and Interface Science (2017)
Discipline: CHEMISTRY
Keywords: Nanocomposite; Visible-light-driven photocatalyst; g-C(3)N(4) nanosheets; g-C(3)N(4)-NS/CuCr(2)O(4).
Affiliations: Department of Chemistry, Faculty of Science, University of Mohaghegh Ardabili, P.O. Box 179, Ardabil, Iran., Department of Chemistry, Faculty of Science, University of Mohaghegh Ardabili, P.O. Box 179, Ardabil, Iran. Electronic address: .

Abstract:  In this paper, CuCr2O4 nanoparticles were decorated on the surface of g-C3N4 nanosheets (g-C3N4-NS) by a facile refluxing process. The structure, composition, morphology, optical, textural, and thermal properties were characterized by XRD, EDX, SEM, TEM, UV-vis DRS, FT-IR, XPS, PL, BET, and TGA techniques. The photocatalytic performance of g-C3N4-NS/CuCr2O4 nanocomposites was assessed by degrading RhB and MB dyes and phenol under visible-light illumination. When the loading amount of CuCr2O4 was 10 wt%, the nanocomposite exhibited the highest activity. Activity of the g-C3N4-NS/CuCr2O4 (10%) nanocomposite refluxed for 3h and calcined at 520°C for 4h was almost 11.8 and 4.8 times greater than those of the bulk g-C3N4 and g-C3N4-NS photocatalysts in degradation of RhB, respectively. In the prepared nanocomposites, nanosheets of g-C3N4 act not only as CuCr2O4 support, but also as co-catalyst. The novel visible-light-active photocatalyst has considerable stability and it can be reused for five times without obvious loss of its photocatalytic activity. 

Retracted: No

PubPeer comments:
 ![file] How to cut a TEM image of a sample (g-C3N4-NS CuCr2O4 (10%) turns it into a TEM image of another sample (g-C3N4 Ag3VO4 AgBr). The interesting thing is that they turned the same TEM image and cut it again and reported as TEM graph of another sample (g-C3N4-NS CuCr2O4 (20%) in another paper. , 
 ![file] As shown in the figures above, for the elemental analysis of two different materials (in two different journals), the same EDS analysis results were used. First, the EDS MAP results for carbon and nitrogen are EXACTLY the same for both samples. Second, there is no correlation between the EDS MAP results and the distribution of these elements in the SEM images of the two samples. , 
 Thanks for your valuable comments. In the paper on the right, g-C3N4 nanosheets (g-C3N4-NS) were synthesized by thermal exfoliation of the bulk g-C3N4. Then, CuCr2O4 nanoparticles were decorated on the surface of g-C3N4-NS via refluxing process and the prepared samples were characterized by XRD, EDX, SEM, TEM, UVu2013vis DRS, FT-IR, XPS, PL, BET, and TGA techniques. According to XRD patterns, presence of peaks at 27.3u02da and 13.1u02da for bulk g-C3N4 and a slight shift in peak at 27.3u02da and decrease of intensity of this peak for g-C3N4-NS, indicated that bulk g-C3N4 and g-C3N4-NS have been correctly synthesized. For the g-C3N4-NS CuCr2O4 nanocomposites, the diffraction peaks of g-C3N4 and tetragonal phase of spinel CuCr2O4 were also observed. The survey XPS spectrum as well as high-resolution XPS spectra for the g-C3N4-NS CuCr2O4 (10%) nanocomposite confirmed the formation of nanocomposite. Regarding g-C3N4 Ag3VO4 AgBr nanocomposites, the photocatalysts were synthesized by refluxing method and characterized by XRD, EDX, SEM, TEM, FT-IR, UV-vis DRS, BET, TGA, and PL instruments. The XRD patterns, EDX and FT-IR spectra of the samples confirmed their formation. For instance, the XRD pattern of the g-C3N4 Ag3VO4 AgBr (10%) nanocomposite, as an optimum photocatalyst with the best performance, exhibited the diffraction peaks for g-C3N4, cubic phase of AgBr, and monoclinic Ag3VO4 and indicated co-existence of g-C3N4, AgBr, and Ag3VO4 counterparts. The EDX spectra exhibited coexistence of corresponding elements too. Furthermore, FT-IR spectrum for the g-C3N4 Ag3VO4 AgBr (10%) nanocomposite showed the characteristic peaks of 806 cm-1 attributed to stretching mode of s-triazine unit of g-C3N4, 788 and 842 cm-1 related to Ag-V and V-O bonds, respectively, and the peaks at 1200-1650 and 3200 cm-1 attributed to the C-N, C=N and NH stretching vibration modes of g-C3N4, respectively. Concerning g-C3N4 Fe3O4 Ag2SO3 nanocomposites, they have been prepared by refluxing procedure and fully characterized by different techniques to prove the preparation of the photocatalysts and investigate their properties. Unfortunately, the wrong images were used unintentionally, although, original images of the photocatalysts were taken at the time and are available. We will immediately contact the journal to inform about the mistake and provide the corrections. We hope that with the help of the editors we can manage the faults, as soon as possible. I, on behalf of authors, apologize for the obvious and careless mistake. Thanks again for your kind comment and precise review. ,