A Comprehensive DFT Investigation of the Adsorption of Polycyclic Aromatic Hydrocarbons onto Graphene
Round 1
Reviewer 1 Report
The manuscript entitled “A comprehensive DFT investigation of the adsorption of Poly-cyclic Aromatic Hydrocarbons onto Graphene” describes the DFT results reveal that the distance between the PAH molecules adsorbed onto the G ranges between 2.47 and 3.98 Å depending on the 13 structure of PAH molecule. The results support this method for employing reliable method employing a Quantitative structure-activity relationship (QSAR) empirical model developed and validated for estimating the adsorption energies of PAH molecules onto graphene.
- The below mentioned article should be cited in the manuscript in the introduction part. a) DFT Study on Interstellar PAH Molecules with Aliphatic Side Groups
The Astrophysical Journal, Volume 892, Number 1
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Author Response
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Reviewer 2 Report
The article "A comprehensive DFT investigation of the adsorption of Poly- 2
cyclic Aromatic Hydrocarbons onto Graphene" considers a very interesting and perspective topic, especially because of its relation with the environment protection. However, in my opinion, the article needs some important improvements, as listed below.
1) Through the text, the same writing of "non-covalent" should be used.
2) Lines 25-28: references should be provided for each of three sentences about PAH.
3) Lines 38-39: "thermal conduction" treatment technique sounds somewhat unclear.
4) Lines 39-40: what are exactly "bioaugmentation, biostimulation"?
5) Line 40: references should be provided regarding the soil treatment techniques.
6) Lines 40-43: references should be provided for both sentences.
7) Line 46: more references should be provided.
8) Lines 49-51: references should be provided.
9) Lines 53-55: references should be provided.
10) Line 60: why exactly the M-11L functional was chosed, and not any dispersion-corrected functionals?
11) Line 69: "The interaction energy, both, in vacuum" - apparently, there is a mistake here?
12) Line 71: comma should be put after "G".
13) Line 72: "one of PAH molecules" - it is unclear: which molecule of PAH?
14) Line 75: is the optimized structure completely flat or slightly distorted?
15) Line 77: the sentence should be corrected as "The geometry was optimized using the M-11L/DNP level of theory."
16) Line 77: "single-point" notation should be used.
17) Lines 79-80: why exactly the Orca approach was used here?
18) Lines 82-83: "The adsorption energy, is evaluated using the well-known method [27–30]. " - what method?
19) Line 97: the caption should be modified.
20) Line 98: "in Figure 3 are".
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Polycyclic aromatic hydrocarbons (PAHs) are persistent pollutants with a wide spectrum of biological toxicity due to their intrinsic features. PAH pollutants are found in both aquatic and terrestrial ecosystems, as well as in the atmosphere and Removal of PAHs from the environment has been a global challenging problem. Now Mehmeti and Sadiku used density functional theory (DFT) computations to understand the interactions with PAHs. They found that the distance between the PAH molecules adsorbed onto the G ranges between 2.47 and 3.98 Å depending on the structure of PAH molecule. Based on the DFT-calculated adsorption energy data, the authors proposed a rapid and reliable method employing a quantitative structure-activity relationship (QSAR) empirical model to predict adsorption energy. The authors’ finding is of good significance, of wide interest and of new physical insight. The proposed adsorption energy prediction method is promising to modify and apply to more polycyclic compounds adsorbed on two-dimensional materials such graphene allotropes and BN. Nevertheless, there are some technical issues should be clarified and some comparisons with literature data of similar systems should be supplemented before the manuscript could be accepted.
The following points are very important to increase the significance and readability of the manuscript and therefore should be addressed and included in the revised manuscript.
(1) In Section 2 (Lines 62-63), the authors wrote: “A lower than 1e-5 kcal/mol convergence standard for the self-consistent-field (SCF) was used for the SCF”. The “SCF” is repeatedly used in the sentence and in addition, I found the “fine” convergence standard is 1X10-5 Ha, here the energy unit is “Ha” but not “kcal/mol” (Please check it). I suggest the authors change this sentence to “A lower than 1X10-5 Ha convergence standard for the self-consistent-field (SCF) was used”.
(2) Please label the equations using numbers (1), (2), etc. For instance, the definition of adsorption energy is (Line 69)
Eadsorption= EG/PAH − (EG+ EPAH) (1)
In addition, I found that the definition equations in Lines 69 and 92 are the same. Why to definite it twice? Therefore, please delete the equation in Line 92 and its explanation and label the equation in Line 126 using “(2)”. It should be pointed out that the letter such as “E” used to represent energy should be printed in italic type in the equation.
(3) Please add the explanation for which atom the grey and white balls stand in Figure 2 or figure caption of Figure 2.
(4) For clarity, please revise the figure caption of Figure 3 to “Equilibrium adsorption distance of the selected PAH molecules on G”. It is very interesting to add in the main text the comparisons of the equilibrium adsorption distances in Figure 3 with other similar adsorption systems such as benzene [distance is 3.05-3.42 Å from Rapacioli, M.; Tarrat, N. Periodic DFTB for supported clusters: Implementation and application on benzene dimers deposited on graphene. Computation 2022, 10, 39. doi: 10.3390/computation10030039], 9,10-Anthraquinone (AQ) [adsorption distance is 3.19 Å from Yu, Y-X., A dispersion-corrected DFT study on adsorption of battery active materials anthraquinone and its derivatives on monolayer graphene and h-BN, J. Mater. Chem. A, 2014, 2, 8910–8917. DOI: 10.1039/c4ta00103f] and phenanthraquinone (PQ) [adsorption distance is 3.14 Å from Yu, Y.-X., Binding energy and work Function of organic electrode materials phenanthraquinone, pyromellitic dianhydride and their derivatives adsorbed on graphene, ACS Appl. Mater. Interfaces 2014, 6, 16267−16275. DOI: 10.1021/am504452a] on graphene. These adsorption distances are comparable, showing the reliability of the reported results by the authors. Therefore addition of the above discussions and comparisons with other similar substances would increase the significance of the manuscript.
(5) The authors reported the values of several Fast and Spatial Descriptor, but their explanations are absent in the main text. Please give full explanation of these Fast and Spatial Descriptors in the main text for easily and better understanding.
(6) The fast estimation of the Eads is very good for PAHs onto G. In order to show the significance of QSAR equation proposed by the authors, it should be discussed that the method is promising to be modified to more complicated systems of organic compounds on graphene analogues such flavonoids on BN [see: Yu, B.; Ren, H.; Piao, X. Towards adsorptive enrichment of flavonoids from honey using h-BN monolayer, ChemPhysChem 2022, 23, e202100828. Doi: 10.1002/cphc.202100828]. In this way, the wide interest of readers can be aroused.
(7) There are some minor errors and/or typos. <i> Please write the data in scientific notation with one figure to the left of the decimal point. For instances, Line 62: “1e−5” should be corrected to “1X10−5”. <ii> Lines 55 and 90, “Graphene” should be corrected to “G” or “graphene”. <iii> Line 72: “Non Covalent Interactions” should be corrected to “non-covalent interactions”. <iv> Line 130: “predictions” should be corrected to “predictions.”.
(8) The format of the article titles in the Reference List should be identical. For instances, <i> In Ref. [1], article title “Polycyclic Aromatic Hydrocarbons: Sources, Toxicity, and Remediation Approaches” should be corrected to “Polycyclic aromatic hydrocarbons: Sources, toxicity, and remediation approaches”. <ii> In Ref. [6], article title “Adsorption of Polycyclic Aromatic Hydrocarbons by Natural, Synthetic and Modified Clays” should be corrected to “Adsorption of polycyclic aromatic hydrocarbons by natural, synthetic and modified clays”. <iii> In Ref. [8], article title “Polycyclic Aromatic Hydrocarbons Adsorption onto Graphene: A DFT and AIMD Study” should be corrected to “Polycyclic aromatic hydrocarbons adsorption onto graphene: A DFT and AIMD study”. <iv> The same issue was also found in Ref. [10], [11], [18] and [19].
Author Response
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Round 2
Reviewer 3 Report
The authors gave revised their manuscript carefully by fully considering the comments and suggestions from all Reviewers. Now the revised version of the manuscript is good enough (although there are several typos that can be handled by the Editors) for being accepted and I would like to recommend it for publication.
