Polyethylene glycol-doped BiZn2VO6 as a high-efficiency solar-light-activated photocatalyst with substantial durability toward photodegradation of organic contaminations
Authors: Omer Nur
Aziz Habibi-Yangjeh
Mahsa Pirhashemi
Galia Pozina
Sami Elhag
Magnus Willander
Journal: RSC Advances (2018)
Discipline: CHEMISTRY
Keywords: BiZn2VO6; nanocompounds; photocatalyst; solar light absorption; polyethylene glycol (PEG)
Affiliations: Department of Science and Technology (ITN), Link√∂ping University, Campus Norrk√∂ping, Sweden, Department of Chemistry, Faculty of Science, University of Mohaghegh Ardabili, Ardabil, Iran, Department of Physics, Chemistry and Biology (IFM), Link√∂ping

Abstract:  In this study, we focus on a simple, low-priced, and mild condition hydrothermal route to construct BiZn2VO6 nanocompounds (NCs) as a novel photocatalyst with strong solar light absorption ability for environmental purification using solar energy. NCs were further doped with polyethylene glycol (PEG) to improve their photocatalytic efficiency for photodegradation processes through inhibition of fast charge carrier recombination rates and higher charge separation efficiency. Surface morphology, phase structure, optical characteristics, and band structure of the as-prepared samples were analyzed using XRD, EDX, XPS, SEM, UV-vis spectroscopy, CL, and BET techniques. PEG-doped BiZn2VO6 NCs were applied as effective materials to degrade various kinds of organic pollutants including cationic and anionic types, and these NCs exhibited excellent photocatalytic efficiency as compared to traditional photocatalysts. In particular, the PEG-doped BiZn2VO6 (0.10% w/v) photocatalyst exhibited highly enhanced photocatalytic performance with improvements of about 46.4, 28.3, and 7.23 folds compared with PEG-doped ZnO nanorods (NRs), pristine BiVO4, and BiZn2VO6 samples, respectively, for the decomposition of congo red (CR) dye. After 40 minutes of sunlight irradiation, 97.4% of CR was decomposed. In this study, scavenging experiments indicated that both hydroxyl radicals and holes play dominant roles in CR photodegradation under simulated solar light irradiation. Meanwhile, the optimal photocatalyst demonstrated good reproducibility and stability for successive cycles of photocatalysis. 

Retracted: No

PubPeer comments:
 Fig 13b appears to contain a duplicated XRD pattern with the only difference being vertical rescaling. Original figure:  I then drew rectangles over parts of the background and vertical lines matched up to major peaks on the upper XRD pattern (black). I then grouped those rectangles and lines and vertically rescaled them as a group (yellow). All of the identically rescaled rectangles and lines match up identically with the lower XRD pattern.:  , 
 Fig.2 XRD patterns for ZnO NRs, PEG-doped ZnO NRs, BiVO4, BiZn2VO6, and PEG-doped BiZn2VO6 with different (w v) percentages of PEG. Five XRD patterns on the top of figure are identical, two on the bottom are also very similar   . , 
 Thallarcha Lechrioleuca clearly has no experience of x-ray powder diffraction. Small peaks are not noise. They should be there. Look up  Rietveld analysis . The accusations are baseless. , 
 #3 You clearly have no experience with Photoshop. Noise or genuine signal, no legitimate measurement method will produce scalable identical results. Allow me to clarify.  , 
 Dr Kuiper, the bottom part of noise was mostly removed in these patterns, but not very carefully. It can be found in some parts of patterns and it is surprisingly similar. Do you believe in diffraction peaks with negative intensity?  , 
 #5 Surprising only to you, because you don t have a clue. It is the same batch of the same stuff, the diffractions peaks will be at the same positions with approximately the same intensity ratios. These accusations are made without any knowledge. It is pretty useless to argue with an anonymous stubborn person who does not have any knowledge whatsoever, who is cocksure with their  discovery , who is unwilling to learn, and who really does not give a damn about ethics at all. , 
 Related article with common co-authors: https: pubpeer.com publications 39F7A3E772552294D3AC69E147D447 , 
 #4 that s what i was trying to show. this is case where doing an image cancellation overlay would be useful. the result would be a blank field. , 
 Yep. The additional effort expended to scale one of the two patterns makes it all the more suspect. , 
 #6 I posted one more similar case specially searching something closer to Dr.Kuiper own publications. It took only 10 minutes to find similar case for doped NiO. https: pubpeer.com publications 7C7AE174E2649C04C43C5C1543F28C What is your opinion Dr.Kuiper? Also diffraction peaks? , 
 #10 Ha! You have been checking my spectra too. If one runs similar samples on the same machine one may see structures that reproduce. I have seen features in spectra that were completely due to small glitches in the mechanics of the monochromator. , 
 #11  Ha! You have been checking my spectra too. No. I have not looked at any of your papers. I checked your google scholar for subjects you might know and searched for  doped NiO  and XRD. You can try it by yourself . My message is that every research field with any random combination of material + XRD or spectra provides examples with figures of that kind. Most often in less than 10 minutes of time. Identical spectra for different samples or in worst case copy- paste of fragments. For any popular materials.  I have seen features in spectra that were completely due to small glitches in the mechanics of the monochromator. Any diffraction or spectra must include some nose by definition and it is random. I see no point to continue this discussion. More examples you can find in my past and next posts. You can find more examples by spending maximum 10-20 minutes of your time. See for yourself if you are true scientist. Don t trust me. Make experiment. Do some search. , 
 Hi Pieter, As for your comment #3, Rietveld analysis doesn t have anything to do with the topic at hand, you re just throwing random XRD-related terms around in the hopes people will shut up. regarding #11, they are diffractograms, not  spectra . You should have learned this in your first lesson on XRD. Also, you do know the monochromator sits before the collimator, and does not have any mechanics that move during the scan, so any structure or spurious peaks produced by the monochromator are cut away by the collimator before it hits the sample, let alone the detector which in these cases isn t even in line with the beam. TL;DR: you re talking nonsense. , 
 My purpose with mentioning  Rietveld was to show that diffractograms can have dense forests of small peaks that should be there according to calculations, reproducible signal, not noise. See for example figures in  And I was referring to _my_ experience from spectroscopy. This method of lay people looking for similarities in traces that was advocated on Leonid Schneider s blog is a kind of witch hunt which inevitably leads to many false positives. , 
 #14 Pieter, it is more relevant to check glycol-doped BiZn2VO6 discussed in this paper. It was first reported in DOI: 10.1039 c6ta10180a XRD figure shows two patterns which are similar but not identical as it is expected. The random noise is clearly different for two patterns.  Next I propose to look on theoretically predicted XRD pattern of BiZn2VO6. Pieter, you cited this paper and why not to compare? http: dro.dur.ac.uk 16568 1 16568.pdf  XRD theory predicts positions of all diffraction peaks. The rest is noise. The angle region 10-20 degrees shows 6 diffraction peaks for theoretical pattern. Only two strongest peaks can be found in 2016 paper and nearly nothing in 2018 paper. Now question to authors. How was BiZn2VO6 identified using XRD? Citation:  With respect to the BiZn2VO6 sample, the diffraction peaks at 23.5 u00b0, 28.9 u00b0, 31.6 u00b0, 34.2 u00b0, 36.9 u00b0, 39.1 u00b0, 46.6 u00b0, and 48.5 u00b0 were indexed to (101), (103), (110), (006), (105), (114), (200), and (116) planes, respectively, of orthorhombic BiZn2VO6 (JCPDS no. 01-075-9214).ref 50 . Reference 50 cites triclinic structure, not orthorhombic. What were the unit cell parameters used for indexing? Old paper from 2016 cites orthorhombic a =11.5 u00b0A, b= 5.5 u00b0A and c =8.5 u00b0A with reference to another paper (Nunes et al). But that paper reports triclinic structure for BiZn2VO6. If authors used orthorhombic structure the indexing is not correct. Fpr example the first peak they index as (101) but according to these unit cell parameters it is expected to be at 12.9 degrees, not at 23.5, The same is for other peaks, no match. The earlier paper from 2016 also do not provide information about experimental unit cell parameters, type of structure or indexing. It is only cited that the structure is orthorhombic. Next images compare Nunes et al data to data from discussed papers. Not sure there was BiZn2VO6 in the studied samples.  , 
 I must admit took some time on this thread and double checked my own understanding of this. It is frankly unbelievable that Dr Pieter Kuiper would defend something which is clearly erroneous and also that anonymous support would be lodged for this. I will be reaching out to Dr Kuiper to ensure this is in fact a legitimate communication. I suspect it is not. There are a number of threads which have emerged over the last week in relation to Aziz Habibi-Yangjeh s team. These all follow a similar format. One might suggest there is a pattern emerging. , 
 Colleagues are also referred to this link for more information; https: twitter.com MicrobiomDigest status 1197623885836931072 , 
 #16 I had wanted to write here that I am convinced by the report of the external reviewer, but my previous comment did not get passed moderation. Yet comments by anonymous accounts about me get published here. And I received a mail message from anonymous account. I do not like this PubPeer thing. , 
 #18 Dear Pieter, moderation is about content, not who is posting them (anonymous or not). You may not  like this PubPeer thing , but it serves as a place for discussion of published papers, and in this case it brought to light serious concerns about two papers. Bad science and misconduct should not remain hidden, and sunlight is the best disinfectant. The authors were found guilty of research misconduct by the Swedish National Board for Assessment of Research Misconduct: https: forbetterscience.com 2020 12 23 omer-nour-and-magnus-willander-guilty-of-research-misconduct This is strongly different from your assertions that  Thallarcha Lechrioleuca clearly has no experience of x-ray powder diffraction and  Look up Rietveld analysis. The accusations are baseless. , 
 #19 Then why did you not publish the message that I wrote months ago? The external expert had those data for his second report and did a meticulous analysis that convincingly shows that the diffraction traces of supposedly different runs are identical. I still maintain that raw data are necessary to conclude that there was duplication. And I am not going to answer mail messages from anonymous accounts. I am surprised that you published the message by this  Atopobium Rimae . ,