Broadband Spectrum Light-Driven PANI/Au/Beta-Cyclodextrin Nanocomposite and Its Light-Triggered Interfacial Carrier Transfer

Round 1

Reviewer 1 Report

Dear Authors,

Q1- Abstract: Why the interaction mechanism between beta-cyclodextrin and aniline is important, what will be the contribution of the study in this field, briefly specify.

Q2-Page 3, line 126-127:   In the experiment, 50 mL, 50 mL, 100 mL aniline solution containing hydroxypropyl-126 β-cyclodextrin (about 10mg/L) were added in 300 or 500 mL glass vessel respectively. Rewrite the statements clearly.

2.2. Loading of aniline in the hydrophobic cavities of beta-cyclodextrin

2.3. Synthesis of Au/polyaniline nanocomposite functionalized with beta-cyclodextrin

The rates given in these sections regarding the loading of aniline monomers into the hydrophobic spaces of beta-cyclodextrin are not clear, the reader has no idea about the composition of the prepared nanocomposites, please specify again or indicate in a table. 1 mL of aniline was added to 2-5 g of hydroxypropyl-p-cyclodextrin, incubated at room temperature for 24-121 72 hours. A range of 2-5 g is not meaningful to the reader.

Q3-Page 4, line 172-173: In experiments, it is noted that aniline monomers are loaded into the hydrophobic spaces of beta-cyclodextrin, but the loading speed is very slow due to the small space of beta-cyclodextrin, about 1-3 days. Support this result with literature.

Q4-Page 5: SEM images of PANi functionalized with beta-cyclodextrin by novel interface polymerization are shown in Figure 1-B and Figure 1-C.

Please indicate what the compositions are in Figure 1 B and C. It is not clear how the difference is achieved. The same question should be answered for the material whose sem images are given in Figure 2, the composition must be clearly stated.

Q5-Page 6-line 193: It is stated that “In comparison with Fig.1, as shown from Fig.2, it is found that the PANi morphology are obviously different” What kind of difference is mentioned, the reader has no clear difference even about the composition.1 mL of aniline is added to 2-5 g of hydroxypropyl-p-cyclodextrin and diluted, in this case it is necessary to explain how the dilution process changes the morphology, it is not possible to understand from the sm images presented.

Q6-Page 6, line 218-219: Why the presence of beta-cyclodextrin acts as a stabilizing agent to the Au/PANi nanocomposite. What is the extent of the interaction with the hydroxy group of cyclodextrin, can you support your result with the literature? Explain how similar effect is observed with poly(sodium-p-styrenesulfonate)

Q7-Page 7: Figure 4. FTIR of series of Au/PANi nanocomposites functionalized with beta-cyclodextrin.

Figure 4 is not clear, give the graph a little larger and with clear regions. What kind of difference was observed between the FTIR spectra of PANi/cyclodextrin and PANi/cyclodextrin/Au(50). Likewise, explain the key difference between the FTIR spectra of PANi/cyclodextrin/Au (50) and PANi/cyclodextrin/Au (100)

Q8-Page 9: XRD results: Au nanoparticles had some strong peaks of 2θ in 38.04 (111), 44.22 (200), 64.69 (220), 77.50 (311). These peaks belong to face-centered cubic of Au. Spectrum for Au nanoparticle should be added to Figure 6.Support this result with lietature.

Q9-Page After the nanocomposite samples have been stored 333 over 5 years at room temperature, to examine their activities of Au/PANi nanocomposites 334 to weak visible light, we examined their photoconductivity to visible light again. Is there a wording mistake here?

Q10-Page 11, line 379-380: Figure 9: Why is the response rate of thick film of PANi/beta-cyclodextrin/Au(50) nanomaterials faster than PANi/beta-cyclodextrin/Au(100), by what mechanism? How the coupling between PANi and Au nanoparticles promoted charge separation and reduced the required excitation power when exposed to incoming light. Explain and support this results.

Author Response

Q1- Abstract: Why the interaction mechanism between beta-cyclodextrin and aniline is important, what will be the contribution of the study in this field, briefly specify.

Thank you for this question. In the abstract, the interaction mechanism between beta-cyclodextrin and aniline was not exhibited. Beta-cyclodextrin acted as dispersing agent and reactive vessel for growth of nanomaterials. Metal nanostructure is one kind of free-electron like materials, polyaniline is conjugated polymer, beta-cyclodextrin is non-conjugated small molecule. For the transfer of carriers photo-generated, the interface between polyaniline and beta-cyclodextrin is unfavorable.

Q2-Page 3, line 126-127:   In the experiment, 50 mL, 50 mL, 100 mL aniline solution containing hydroxypropyl-126 β-cyclodextrin (about 10mg/mL) were added in 300 or 500 mL glass vessel respectively. Rewrite the statements clearly.

Thank you for this question. Table was added in the revision for clearly.

2.2. Loading of aniline in the hydrophobic cavities of beta-cyclodextrin

2.3. Synthesis of Au/polyaniline nanocomposite functionalized with beta-cyclodextrin

The rates given in these sections regarding the loading of aniline monomers into the hydrophobic spaces of beta-cyclodextrin are not clear, the reader has no idea about the composition of the prepared nanocomposites, please specify again or indicate in a table. 1 mL of aniline was added to 2-5 g of hydroxypropyl-p-cyclodextrin, incubated at room temperature for 24-121 72 hours. A range of 2-5 g is not meaningful to the reader.

Thank you for this question. Table was added in the revision for clearly. Wide range is not meaningful to the reader, we have revised it in the revision.

Q3-Page 4, line 172-173: In experiments, it is noted that aniline monomers are loaded into the hydrophobic spaces of beta-cyclodextrin, but the loading speed is very slow due to the small space of beta-cyclodextrin, about 1-3 days. Support this result with literature.

Thank you for this question. Due to beta-cyclodextrin holding hydrophobic cavities, at first, we intended loading C60 using cyclodextrin, calix[x]arene, cucurbituril for preventing aggregation of C60. The results were failed. We tried loading aniline monomers, standing about 1-3 days, satisfaction effect was obtained. The author has foundation for synthesis and properties of polyaniline. The polymerization of aniline is exothermic reaction, dilute aniline aqueous solution polymerization is favorable for low-dimensional polyaniline in previous studies. In large number of literatures, beta-cyclodextrin is used for loading and releasing drugs in biomedical fields. We focused on functional nanocomposite and its property. The purpose of using beta-cyclodextrin is different.

Q4-Page 5: SEM images of PANi functionalized with beta-cyclodextrin by novel interface polymerization are shown in Figure 1-B and Figure 1-C.

Please indicate what the compositions are in Figure 1 B and C. It is not clear how the difference is achieved. The same question should be answered for the material whose sem images are given in Figure 2, the composition must be clearly stated.

Thank you for this question. We have revised in the revision.

Q5-Page 6-line 193: It is stated that “In comparison with Fig.1, as shown from Fig.2, it is found that the PANi morphology are obviously different” What kind of difference is mentioned, the reader has no clear difference even about the composition.1 mL of aniline is added to 2-5 g of hydroxypropyl-p-cyclodextrin and diluted, in this case it is necessary to explain how the dilution process changes the morphology, it is not possible to understand from the sm images presented.

Thank you for this question. The difference of A, B, and C is clearly. A and B showed nanowire of polyaniline, but the background of B exhibited a layer of polymer-like film, which is the results of presence of hydroxypropyl-p-cyclodextrin. Compared with Fig. 1-A, B shows that the PANi functionalized with beta-cyclodextrin are embedded in polymer-like film, C showed the surface of PANi nanowires are not smooth, containing a large number of porous structure and small particles, the space between particles is relatively more bigger, though they are still exhibited morphology of nanowires-like structure. This is results of gravity of liquid drop and slow releasing rate. Regarding the dilution process changes the morphology, it needs introducing some progress of synthesis of conductive polymer. Ar first, synthesis of low-dimensional conductive polymer needs adding some hard templates and soft templates, afterwards, two papers from Angew. Chem. Int. Ed. and Advanced Materials introduced dilution polymerization could synthesized low-dimensional conductive polymers [Richard Kaner and co-workers, Nanofiber Formation in the Chemical Polymerization of Aniline: A Mechanistic Study, Angewandte Chemie International Edition, 2004, 43, 5817-5821. N.-R. Chiou, A. J. Epstein, Polyaniline Nanofibers Prepared by Dilute Polymerization, Advanced Materials, 2005, 17(13):1679 - 1683]. According this reference, we prepared low-dimensional conductive polymers without any hard templates and soft templates.

Q6-Page 6, line 218-219: Why the presence of beta-cyclodextrin acts as a stabilizing agent to the Au/PANi nanocomposite. What is the extent of the interaction with the hydroxy group of cyclodextrin, can you support your result with the literature? Explain how similar effect is observed with poly(sodium-p-styrenesulfonate)

Thank you for this question. Hydroxypropyl-β-cyclodextrin is a water soluble molecule, endow with hydrophobic cavities and hydrophilic surface, and its functionality is similar to that of surfactant, which has hydrophobic group and hydrophilic group. The results indicated that the dispersion solution of Au/PANi nanoparticles containing hydroxypropyl-β-cyclodextrin has excellent stability in water, precipitation is difficult to occur for a long time. The dispersion effects are very similar to that of our previous report adding a small amount of poly(sodium-p-styrenesulfonate) (PSS). Poly(sodium-p-styrenesulfonate) (PSS) is one of the typical polymer surfactants, which is widely used in layer by layer assembly, organic solar cells, and so on. In our many experiments, we also used poly(sodium-p-styrenesulfonate) (PSS). Of course, other properties are different. We only focused on the dispersion effect and stability for Au/PANi nanocomposite. Hydroxypropyl-β-cyclodextrin molecule acted as interlayer role between water phase and Au/PANi nanocomposite in our study.

Q7-Page 7: Figure 4. FTIR of series of Au/PANi nanocomposites functionalized with beta-cyclodextrin.

Figure 4 is not clear, give the graph a little larger and with clear regions. What kind of difference was observed between the FTIR spectra of PANi/cyclodextrin and PANi/cyclodextrin/Au(50). Likewise, explain the key difference between the FTIR spectra of PANi/cyclodextrin/Au (50) and PANi/cyclodextrin/Au (100)

Thank you for this question. There is no difference between the FTIR spectra of PANi/cyclodextrin and PANi/cyclodextrin/Au(50). Likewise, no difference between the FTIR spectra of PANi/cyclodextrin/Au (50) and PANi/cyclodextrin/Au (100). Difference is presented between PANi and PANi/cyclodextrin, i.e. sample with or without cyclodextrin. The expression of this section is not very clearly due to my English. We have revised it in the revision. Simple qualitative characterization was carried out with FTIR. The emphasis is put on property of nanocomposite.

Q8-Page 9: XRD results: Au nanoparticles had some strong peaks of 2θ in 38.04 (111), 44.22 (200), 64.69 (220), 77.50 (311). These peaks belong to face-centered cubic of Au. Spectrum for Au nanoparticle should be added to Figure 6.Support this result with lietature.

Thank you for this question. We added XRD PDF No. of Au nanoparticle in the revision.

Q9-Page After the nanocomposite samples have been stored 333 over 5 years at room temperature, to examine their activities of Au/PANi nanocomposites 334 to weak visible light, we examined their photoconductivity to visible light again. Is there a wording mistake here?

Thank you for this question. In the near 20 years of X. Ma for organic/inorganic nanocomposite and its properties study, many nanocomposite samples were stored at room temperature for a long time, and some of them were determined at interval time. The dispersion solution of Au/PANi nanoparticles containing hydroxypropyl-β-cyclodextrin has excellent stability in water, precipitation is difficult to occur for a long time. After the nanocomposite samples have been stored over 5 years at room temperature, to examine their activities of Au/PANi nanocomposites to weak visible light, we examined their photoconductivity to visible light again. The sample still exhibited good photoconductivity. This is indirectly indicated avoiding aggregation of Au nanoparticle due to good dispersion effect by the way. The photoconductivity in the paper is determined with the nanocomposite samples being stored over 3 years at room temperature.

Q10-Page 11, line 379-380: Figure 9: Why is the response rate of thick film of PANi/beta-cyclodextrin/Au(50) nanomaterials faster than PANi/beta-cyclodextrin/Au(100), by what mechanism? How the coupling between PANi and Au nanoparticles promoted charge separation and reduced the required excitation power when exposed to incoming light. Explain and support this results.

Thank you for this question. Au nanoparticles generally have plasmon resonance properties in the region of visible light. The gap distance between Au nanoparticle also affected plasmon resonance properties heavily. Compared with PANi/beta-cyclodextrin/Au(50) nanomaterials , the content of Au nanoparticle in PANi/beta-cyclodextrin/Au(100) sample is higher. However, the content of organic component is similar, this illustrated that the gap distance between Au nanoparticle in nanocomposite would affect the photoresponse. This is a reasonable explanation based on experimental results. Otherwise, plasmon resonance properties of Au nanoparticle located in visible light region. However, the photocurrent response of nanocomposite covered the visible light and NIR. This illustrated that the band gap of nanocomposite narrowed down. Based on band gap engineering, band gap narrowing of nanocomposite showed strong charge transfer between Au nanoparticle and PANi since Au nanoparticles are free-electrons-like materials. The coupling between PANi and Au nanoparticles resulted in strong charge transfer, finally led to narrowing the band gap of nanocomposite.

Reviewer 2 Report

This paper shows the light driven capabilities of  PANi/Au/Beta-Cyclodextrin Nanocomposites. This work is interesting and important. However, it needs some changes as suggested below:

1- The introduction requires more comparison with similar composites in the recent literature. In addition, clear and detailed applications should be discussed in a better way.

2- The references are quite old with almost no citations from 2018-2022!

3- The photodetector schematic is missing figure caption number. Therefore, all consequent figures will be shifted.

4- In Table 1, what is et al within Cl element?

5- Why did the 100 mW make shift in photocurrent in Fig 11?

6- The physical explanation of LUMO carriers need a reference.

7- Comparison between response of device between recently fabricated and 5-years old device should be clarified by figures.

8- SEM images should be captioned in a, b, c...within the same figure.

9- Please revise grammar and different typos.

Author Response

1- The introduction requires more comparison with similar composites in the recent literature. In addition, clear and detailed applications should be discussed in a better way.

Thank you for this question. We have revised it appropriately. Otherwise, Au, polyaniline and beta-cyclodextrin belong to three kinds of different research fields. The representative progress and applications were summarized in the introduction. Afterwards, some key cross issues would be appeared from interdiscipline viewpoint, and then different focus of this study would be showed. We focused on complementary and cross fields.

2- The references are quite old with almost no citations from 2018-2022!

Thank you for this question. We have added several 2018-2022 references appropriately. A paragraph was added to introduce the progress of 2018-2022.

3- The photodetector schematic is missing figure caption number. Therefore, all consequent figures will be shifted.

Thank you for this question. We have added figure caption number in the revision.

4- In Table 1, what is et al within Cl element?

Thank you for this question. Cl element derived from Au precursor (chloroauric acid).

5- Why did the 100 mW make shift in photocurrent in Fig 11?

Thank you for this question. The starting time of exposure light is different. This did not affect the comparison for Y-axis value.

6- The physical explanation of LUMO carriers need a reference.

Thank you for this question. In the fields of inorganic semiconductor, we are used to describing band gap using VB and CB, and in organic semiconductor, we ordinary utilizing HOMO and LUMO energy level, HOMO and LUMO are highest occupied and lowest unoccupied molecular orbital, that is bonding orbital and unbonding orbital. It is very similar to that of VB and CB. In the study of photodynamic process, several photophysics issues are involved in, such as, excitation generation, recombination, free electrons and holes generated from excitation, electron/electron scattering, electron/phonon scattering, photoluminescence, impurity energy level, and so on. There is large number of references on photophysics process. Regarding to the physical explanation of LUMO carriers, we had ever observed a reference on LUMO carriers in AIP journals, however, it is not found recently. My background is not physics, is polymer and materials physics and chemistry. The explanatory depth is not sufficient compared with physics background. LUMO carriers are different for N-typical and P-typical semiconductor. Thank you again for this question. Some references on HOMO and LUMO energy level and physical explanation of mechanism of charge transfer by light inducement were added in the revision.

7- Comparison between response of device between recently fabricated and 5-years old device should be clarified by figures.

Thank you for this question. In the near 20 years of X. Ma for organic/inorganic nanocomposite and its properties study, many nanocomposite samples were stored at room temperature for a long time, and some of them were determined at interval time. The dispersion solution of Au/PANi nanoparticles containing hydroxypropyl-β-cyclodextrin has excellent stability in water, precipitation is difficult to occur for a long time. After the nanocomposite samples have been stored over 5 years at room temperature, to examine their activities of Au/PANi nanocomposites to weak visible light, we examined their photoconductivity to visible light again. The sample still exhibited good photoconductivity, however, system examination was not carried out. The photoconductivity in the paper is determined with the nanocomposite samples being stored over 3 years at room temperature. This is indirectly indicated avoiding aggregation of Au nanoparticle due to good dispersion effect by the way. Since photophysics process of organic/inorganic interface is more complex, many photophysics issues were involved in during the period of sample storing. We intended to discuss these issues in other inorganic/organic nanocomposite system due to our collecting many nanocomposites system studies. Thank you again for this question.

8- SEM images should be captioned in a, b, c...within the same figure.

 Thank you for this question. We revised it in the revision.

9- Please revise grammar and different typos.

 Thank you for this question. We have checked the grammar in the revision.

Reviewer 3 Report

Manuscript is interesting with significant work for the scientific community. I would recommend minor revision to improve the quality of the paper:

1. A schematic should be included with the manuscript showing the synthesis, functioning of the nanomaterials...

2. Introduction part is too long ...should be shorten with only important content..

3. Last para of section 2: "In this study, the structure schematic diagram of photo-detector prototype device 164 consisting of a organic/inorganic nanocomposite thick film on PET substrate and Au as 165 electrodes, similar to that of some references [118] reported that quartz acting substrate 166 and Au as electrodes." Need to improve...not very clear.....

3. Scale bar in SEM images are not very clear...

4. Same in TEM images...can be put manually with respect to the original scale bar...

5. What means weight % in Table 1..?

6. Last para of Section 3 must include the important references.

7. Result and discussion part should be modified and justified with literature with proper referencing.

Author Response

1. A schematic should be included with the manuscript showing the synthesis, functioning of the nanomaterials...

Thank you for this question. We added a schematic showing the synthesis and multi-functionality of the nanomaterials in the revision.

2. Introduction part is too long ...should be shorten with only important content..

Thank you for this question. We also feel a little long for introduction. However, Au, polyaniline and beta-cyclodextrin belong to three kinds of different research fields. The representative progress and applications were summarized. Afterwards, some key cross issues would be appeared from interdiscipline viewpoint, and then different focus of this study would be showed. The introduction would be shorten as soon as possible in the revision.

3. Last para of section 2: "In this study, the structure schematic diagram of photo-detector prototype device 164 consisting of a organic/inorganic nanocomposite thick film on PET substrate and Au as 165 electrodes, similar to that of some references [118] reported that quartz acting substrate 166 and Au as electrodes." Need to improve...not very clear.....

Thank you for this question. We have revised it in the revision. We used Au gap electrodes on PET substrate, and reference was reported using Au gap electrodes on quartz substrate. Its structure is very similar.

4. Scale bar in SEM images are not very clear...

Thank you for this question. Scale bar in SEM images is original Figure from SEM instrument. We checked it again. It can be seen in printing revision. Subsequently, it can be improved with blod font by manual approach.

5. Same in TEM images...can be put manually with respect to the original scale bar...

Thank you for this question. Scale bar in TEM images is original Figure from TEM instrument. We checked it again. It can be seen in printing revision. Subsequently, it can be improved with blod font by manual approach.

6. What means weight % in Table 1..?

Thank you for this question. We added weight % in the revision.

7. Last para of Section 3 must include the important references.

Thank you for this question. We added some references in the revision.

8. Result and discussion part should be modified and justified with literature with proper referencing.

 Thank you for this question. We have revised it appropriately. Some references on HOMO and LUMO energy level and mechanism of charge transfer were added in the revision.