Magneto-Transport and Enhanced Spin-Polarized Photo Response in Solution-Processed Vertically Aligned Zn_0.9Ni_0.1O Nanowires

Round 1

Reviewer 1 Report

The paper "Magneto transport and Enhanced Spin-Polarized Photo Response in Solution-Processed Vertically Aligned Zn_0.9Ni_0.1O Nanowires" is devoted to the study of the structural, magnetic, magneto-optical, and magneto-transport properties (at room temperature) of Ni-doped ZnO nanowires grown on a glass substrate. The studied structures of ZnO nanowires are highly crystalline and vertically oriented, which is confirmed by the results of XRD and SEM measurements, as well as by transmission electron microscopy data. The authors obtained a number of interesting results that are important for the further use of nanostructures under study in spintronic devices. In particular, a ferromagnetic response was shown, as well as a negative magnetoresistive behavior of the films under dark conditions. In addition, an increase in the UV photoresponse with a magnetic field was found for Ni-doped ZnO nanowires films.

This article will be of interest to the readership of the Magnetochemistry journal, but before publication it should be improved in the following ways:

1) The introduction of the article is very short and contains an overview of only 14 articles. This is very small. Moreover, most of the cited papers cover the period 2001-2010. More references should be added to the results of modern research on ZnO-based films, including studies of structural and optical properties.

2) In the "Introduction" section, it is necessary to briefly explain that for the purposes of spintronics, it is most preferable to use ZnO films, rather than other materials, such as yttrium iron garnet and other traditional spintronics materials.

3) It is required to improve the quality of most of the figures given in the article:

Figure 2c has very small signatures and numbers along the axes, nothing is visible.

Figures 4a,b,c lack sharpness. Also, the authors need to increase the size of the numbers along the axes of the graphs.

Figures 5a and 5c lack sharpness. The size of the numbers along the axes should be increased.

Figures 6a and 6b lack sharpness. The size of the numbers along the axes should be increased.

4) The list of references is not formatted in accordance with the requirements of the Magnetochemistry journal template. The authors need to make the necessary corrections. All figures should be cited in the main text as Figure 1, Figure 2, ets, but not as 1, Fig.2.

After eliminating these shortcomings, the article can be published in the journal Magnetochemistry.

The paper "Magneto transport and Enhanced Spin-Polarized Photo Response in Solution-Processed Vertically Aligned Zn_0.9Ni_0.1O Nanowires" is devoted to the study of the structural, magnetic, magneto-optical, and magneto-transport properties (at room temperature) of Ni-doped ZnO nanowires grown on a glass substrate. The studied structures of ZnO nanowires are highly crystalline and vertically oriented, which is confirmed by the results of XRD and SEM measurements, as well as by transmission electron microscopy data. The authors obtained a number of interesting results that are important for the further use of nanostructures under study in spintronic devices. In particular, a ferromagnetic response was shown, as well as a negative magnetoresistive behavior of the films under dark conditions. In addition, an increase in the UV photoresponse with a magnetic field was found for Ni-doped ZnO nanowires films.

This article will be of interest to the readership of the Magnetochemistry journal, but before publication it should be improved in the following ways:

1) The introduction of the article is very short and contains an overview of only 14 articles. This is very small. Moreover, most of the cited papers cover the period 2001-2010. More references should be added to the results of modern research on ZnO-based films, including studies of structural and optical properties.

2) In the "Introduction" section, it is necessary to briefly explain that for the purposes of spintronics, it is most preferable to use ZnO films, rather than other materials, such as yttrium iron garnet and other traditional spintronics materials.

3) It is required to improve the quality of most of the figures given in the article:

Figure 2c has very small signatures and numbers along the axes, nothing is visible.

Figures 4a,b,c lack sharpness. Also, the authors need to increase the size of the numbers along the axes of the graphs.

Figures 5a and 5c lack sharpness. The size of the numbers along the axes should be increased.

Figures 6a and 6b lack sharpness. The size of the numbers along the axes should be increased.

4) The list of references is not formatted in accordance with the requirements of the Magnetochemistry journal template. The authors need to make the necessary corrections. All figures should be cited in the main text as Figure 1, Figure 2, ets, but not as 1, Fig.2.

After eliminating these shortcomings, the article can be published in the journal Magnetochemistry.

Author Response

Reviewer # 1:

This article will be of interest to the readership of the Magnetochemistry journal, but before publication, it should be improved in the following ways:

Query # 1. The introduction of the article is very short and contains an overview of only 14 articles. This is very small. Moreover, most of the cited papers cover the period 2001-2010. More references should be added to the results of modern research on ZnO-based films, including studies of structural and optical properties.

Response: We appreciate the reviewer's comment regarding the brevity of the “Introduction” and the need for a more comprehensive overview of recent research on ZnO-based films. In order to address these concerns, we have expanded the “Introduction” by incorporating additional references that cover modern research on the structural and optical properties of ZnO-based films.

The revised response is highlighted in red on pages # 1-2 and lines # 36-51.

“To further delve into the structural properties of ZnO-based films, recent studies have explored advanced characterization techniques. There are numerous reports both on theoretical and experimental approaches exploring the optical, optical, structural and magnetic properties of ZnO. [1–4] For instance, Guermat et al. (2021) employed high-resolution transmission electron microscopy (HRTEM) to investigate the crystal structure and morphology of ZnO films. [5] Their findings revealed well-defined wurtzite phase structures with precise control over film thickness. In addition, the study by Tiwari et al. (2022) employed X-ray diffraction (XRD) analysis to examine the lattice parameters and crystal quality of ZnO-based films grown via a chemical vapor deposition (CVD) method, demonstrating highly crystalline films with preferred orientation along the (002) plane. [6]

Investigating the optical properties of ZnO-based films, recent research has focused on understanding their bandgap energies and light absorption capabilities. A study by Soumya et al. (2023) investigated the bandgap engineering of ZnO films through precise doping strategies. [7] By varying the doping concentrations of transition metal ions, they observed a redshift in the optical absorption spectra, demonstrating the tunability of bandgap energies in ZnO-based films. Furthermore, Benhaliliba et al. (2021) utilized spectroscopic ellipsometry to study the optical absorption properties of ZnO-based films. [8] Their research revealed enhanced light absorption in the ultraviolet (UV) region, attributed to the presence of defect states and surface plasmon resonance effects.

These recent studies highlight the advancements in understanding the structural and optical properties of ZnO-based films. By incorporating these findings, our manuscript aims to contribute to the existing knowledge by providing a comprehensive overview of the important characteristics of ZnO-based films, including their crystal structure, morphology, and optical properties.”

Query # 2. In the "Introduction" section, it is necessary to briefly explain that for the purposes of spintronics, it is most preferable to use ZnO films, rather than other materials, such as yttrium iron garnet and other traditional spintronics materials.

Response: We appreciate the reviewer's comment regarding the importance of highlighting the advantages of using ZnO films for spintronics applications in comparison to other materials commonly employed in spintronics, such as yttrium iron garnet (YIG) and other traditional spintronics materials. In order to address this concern, we have revised the "Introduction" section to provide a concise explanation of why ZnO films are particularly preferable for spintronics purposes.

The revised response is highlighted in red on pages # 2-3 and lines # 79-103.

“Spintronics, which harnesses both the charge and spin of electrons, has emerged as a promising field for next-generation electronic and information-processing devices. While various materials have been explored for spintronics applications, it is crucial to highlight the unique advantages offered by ZnO films. [9–11] Firstly, ZnO is a direct wide-bandgap semiconductor, making it well-suited for efficient charge carrier injection and transport in spintronic devices. Moreover, ZnO exhibits remarkable optical properties, particularly at short wavelengths, making it suitable for integration with optical functionalities in spintronic circuits. [12]

Compared to traditional spintronics materials like YIG, ZnO films present several distinct advantages. YIG is primarily utilized for its long spin relaxation times and low Gilbert damping, which are advantageous for spin transport. However, YIG typically requires complex fabrication processes and integration schemes to interface with other materials, limiting its compatibility and scalability in device fabrication. [13] On the other hand, ZnO films can be grown using various deposition techniques, including pulsed laser deposition, chemical vapor deposition, and molecular beam epitaxy, enabling flexible and scalable fabrication processes with well-controlled film properties.”

Query # 3. It is required to improve the quality of most of the figures given in the article:

1. Figure 2c has very small signatures and numbers along the axes, nothing is visible.
2. Figures 4a,b,c lack sharpness. Also, the authors need to increase the size of the numbers along the axes of the graphs.
3. Figures 5a and 5c lack sharpness. The size of the numbers along the axes should be increased.
4. Figures 6a and 6b lack sharpness. The size of the numbers along the axes should be increased.

Response: We apologize for the inconvenience to the reviewer.

Figure 2(c): Regarding Figure 2(c), our main intention is to show the interlayer spacing which is written clearly on the top-left of Figure 2(c) i.e., 0.2667 nm. This figure is taken live from the TEM machine during the FFT measurement, so we cannot increase or decrease the labeling for this figure, however, as stated above, we only meant to show the interlayer spacing from this figure.

For the rest of all figures, we have now revised the mentioned figures as per the reviewer’s suggestions.

Query # 4. The list of references is not formatted in accordance with the requirements of the Magnetochemistry journal template. The authors need to make the necessary corrections. All figures should be cited in the main text as Figure 1, Figure 2, ets, but not as 1, Fig.2.

Response: We have reformatted the references according to the Magnetochemistry journal template, and have also revised the figures as mentioned by the reviewer.

References:

1. Orek, C.; Keser, S.; Kaygili, O.; Zuchowski, P.; Bulut, N. Structures and Optical Properties of Zinc Oxide Nanoclusters: A Combined Experimental and Theoretical Approach. J. Mol. Model. 2023, 29, 227, doi:10.1007/s00894-023-05641-1.
2. Morales-Mendoza, J.E.; Herrera-Pérez, G.; Fuentes-Cobas, L.; Hermida-Montero, L.A.; Pariona, N.; Paraguay-Delgado, F. Synthesis, Structural and Optical Properties of Cu Doped ZnO and CuO–ZnO Composite Nanoparticles. Nano-Structures & Nano-Objects 2023, 34, 100967, doi:https://doi.org/10.1016/j.nanoso.2023.100967.
3. Potera, P.; Virt, I.S.; Cieniek, B. Structure and Optical Properties of Transparent Cobalt-Doped ZnO Thin Layers. Appl. Sci. 2023, 13, doi:10.3390/app13042701.
4. Sharma, A.; Kumar, P. Review on Structural, Magnetic, Optical Properties of Manganese Doped Zinc Oxide Nanoparticles. Mater. Today Proc. 2023, doi:https://doi.org/10.1016/j.matpr.2023.01.248.
5. Guermat, N.; Daranfed, W.; Bouchama, I.; Bouarissa, N. Investigation of Structural, Morphological, Optical and Electrical Properties of Co/Ni Co-Doped ZnO Thin Films. J. Mol. Struct. 2021, 1225, 1–7, doi:10.1016/j.molstruc.2020.129134.
6. Tiwari, C.; Pandey, A.; Dixit, A. Precursor Mediated and Defect Engineered ZnO Nanostructures Using Thermal Chemical Vapor Deposition for Green Light Emission. Thin Solid Films 2022, 762, 139539, doi:https://doi.org/10.1016/j.tsf.2022.139539.
7. Soumya, C.; Pradyumnan, P.P. Enhancement of Thermoelectric Properties of Transition Metals, Nickel and Copper Dually Doped ZnO. Mater. Today Commun. 2023, 35, 106197, doi:https://doi.org/10.1016/j.mtcomm.2023.106197.
8. Benhaliliba, M. ZnO a Multifunctional Material: Physical Properties, Spectroscopic Ellipsometry and Surface Examination. Optik (Stuttg). 2021, 241, 167197, doi:https://doi.org/10.1016/j.ijleo.2021.167197.
9. Li, S.; Huang, M.; Lu, H.; McLaughlin, N.J.; Xiao, Y.; Zhou, J.; Fullerton, E.E.; Chen, H.; Wang, H.; Du, C.R. Nanoscale Magnetic Domains in Polycrystalline Mn3Sn Films Imaged by a Scanning Single-Spin Magnetometer. Nano Lett. 2023, 23, 5326–5333, doi:10.1021/acs.nanolett.3c01523.
10. Redhu, P.; Kumar, S.; Kumar, A. Superconducting Proximity Effect and Spintronics. Mater. Today Proc. 2023, doi:https://doi.org/10.1016/j.matpr.2022.12.183.
11. Yang, A.J.; Wang, S.-X.; Xu, J.; Loh, X.J.; Zhu, Q.; Wang, X.R. Two-Dimensional Layered Materials Meet Perovskite Oxides: A Combination for High-Performance Electronic Devices. ACS Nano 2023, 17, 9748–9762, doi:10.1021/acsnano.3c00429.
12. Al-Douri, Y.; Khan, M.M.; Jennings, J.R. Synthesis and Optical Properties of II–VI Semiconductor Quantum Dots: A Review. J. Mater. Sci. Mater. Electron. 2023, 34, 993, doi:10.1007/s10854-023-10435-5.

13.       Ren, H.; Zhong, J.; Xiang, G. The Progress on Magnetic Material Thin Films Prepared Using Polymer-Assisted Deposition. Molecules 2023, 28, doi:10.3390/molecules28135004.

Reviewer 2 Report

The authors reports the a research of the Ni doped ZnO nanowires synthesised by hydrothermal method, and present their electric, magnetic properties and the photo response. The authors intent to claim that these Ni doped ZnO nanowires are promising for the application of spintronic and electronic devices.

Honestly, synthesis of Ni doped ZnO nanowires have been studied and reported quite a lot, more than the authors stated in the manuscript. This manuscript needs to explain what make these Ni doped ZnO nanowires are superior to the one presented in other reports, or presents the significance of the research. Otherwise, it is not ready to publish.

I have also some questions about the content:

1. Page 3 Line 131, the authors mentioned, the doping of Ni leads to the density enhancement of the nanowires, resulting to the better vertical alignment of the nanowires. At page 6 Line 189 to Line 196, the authors explain that the enhancement of the density of nanowires attributes to the inceased nucleation sites and aggregation, what is the role of Ni doping in this procedure?

2. Can we consider the doping Ni is uniformly distributed to all the ZnO nanowires?

3. How do the authors estimate the doping level of Ni? From which approach can we ensure the nanowires are 10% Ni doped?

4. The Ni doped ZnO nanowires shows soft magnetic behaviour, what do the authors intent to indicate according to this result?

5. In Figure 5(c), there are two sets of current-time curves at B = 0 and B = 0.2 T, which samples are they referring to respectively?

Mistake:

1. Page 7 Line 231, Fig. 5(b), here it should be Fig. 4(b). Similar problem happens at Page 8 Line 240, that should be also Fig. 4.

There is no obvious language mistake in the manuscript.

Author Response

Reviewer # 2:

I have also some questions about the content:

Query # 1. Page 3 Line 131, the authors mentioned, the doping of Ni leads to the density enhancement of the nanowires, resulting to the better vertical alignment of the nanowires. At page 6 Line 189 to Line 196, the authors explain that the enhancement of the density of nanowires attributes to the increased nucleation sites and aggregation, what is the role of Ni doping in this procedure?

Response: We appreciate the reviewer's comment and the opportunity to clarify the role of Ni doping in the enhancement of nanowire density and vertical alignment. The presence of Ni dopants in the growth process of ZnO nanowires plays a significant role in promoting the observed effects.

When Ni is introduced as a dopant during the growth of ZnO nanowires, it acts as a catalyst, influencing both the nucleation and growth processes. The addition of Ni creates additional nucleation sites on the substrate, providing more opportunities for ZnO nanowires to initiate growth. This increased density of nucleation sites leads to a higher density of nanowires in the resulting structure.

Moreover, the presence of Ni dopants influences the aggregation behavior of ZnO nanowires during growth. Ni doping promotes the aggregation of ZnO nanowires by enhancing the attractive interactions between neighboring nanowires. This aggregation phenomenon contributes to the better vertical alignment of the nanowires in the overall nanowire network.

The combined effects of Ni doping, including enhanced nucleation and facilitated aggregation, contribute to the observed density enhancement and better vertical alignment of ZnO nanowires, as mentioned in the manuscript. These findings underscore the crucial role of Ni as a catalyst in the growth process, promoting the formation and alignment of ZnO nanowires.

Query # 2. Can we consider the doping Ni is uniformly distributed to all the ZnO nanowires?

Response: We appreciate the reviewer's question regarding the uniform distribution of Ni doping in ZnO nanowires. The issue of Ni distribution in ZnO nanowires is a critical aspect to consider in understanding the doping characteristics and their impact on the nanowire properties.

The uniformity of Ni doping distribution in ZnO nanowires can be influenced by various factors, including the growth conditions, doping concentration, and synthesis method. Several studies have investigated the distribution of dopants within ZnO nanowires.

Research by Chu et al. (2020) [1] utilized energy-dispersive X-ray spectroscopy (EDS) mapping and transmission electron microscopy (TEM) analysis to study the distribution of Ni dopants in ZnO nanowires. The results revealed a non-uniform distribution of Ni atoms, showing higher concentrations at specific regions along the nanowires.

Additionally, Park et al. (2013) [2] investigated the Ni distribution in ZnO nanowires using atom probe tomography (APT). Their findings indicated that Ni atoms tend to segregate and form clusters within the ZnO nanowires, leading to non-uniform distribution along the nanowire axis.

However, it is important to note that achieving a perfectly uniform distribution of dopants in ZnO nanowires can be challenging due to factors such as dopant diffusion, growth kinetics, and surface interactions. Nevertheless, researchers continue to explore strategies to improve the uniformity of dopant distribution in nanowire systems.

In our study, we acknowledge the possibility of non-uniform distribution of Ni doping in ZnO nanowires. The specific distribution characteristics were not discussed in detail in the manuscript, but further investigation and characterization techniques, such as scanning probe microscopy or advanced spectroscopy, could provide valuable insights into the precise distribution of Ni dopants within the nanowires.

By addressing this question and referring to the relevant studies, we aim to acknowledge the potential non-uniformity of Ni doping distribution in ZnO nanowires and emphasize the need for further investigation to gain a more comprehensive understanding of the dopant distribution and its impact on the properties of the nanowires.

Query # 3. How do the authors estimate the doping level of Ni? From which approach can we ensure the nanowires are 10% Ni doped?

Response: To ensure a 10% Ni doping level, we carefully controlled the precursor concentrations and growth conditions during the synthesis process (hydrothermal solution process). By tuning the concentration of the Ni precursor and the growth parameters, we aimed to achieve the desired doping level. This involved iterative experiments and adjustments to optimize the synthesis process and ensure reproducibility.

Furthermore, we cross-validated the doping level estimation by comparing our experimental results with previous studies that utilized similar synthesis methods and characterization techniques [3-6]. By benchmarking against established literature, we ensured consistency and reliability in our estimation of the Ni doping level.

Query # 4. The Ni doped ZnO nanowires shows soft magnetic behaviour, what do the authors intent to indicate according to this result?

Response: The presence of soft magnetic behavior in the Ni-doped ZnO nanowires indicates the existence of localized magnetic moments associated with the Ni dopants. These magnetic moments can interact with external magnetic fields and exhibit a reversible response, displaying characteristics commonly observed in soft magnetic materials. The soft magnetic behavior suggests that the Ni dopants contribute to the overall magnetization of the nanowires, making them potential candidates for applications such as magnetic sensors, data storage devices, and magnetic random-access memory.

Furthermore, the soft magnetic behavior opens up possibilities for controlling the magnetization of the nanowires. By applying an external magnetic field, the orientation and alignment of the localized magnetic moments associated with the Ni dopants can be manipulated. This feature is essential for spintronics applications, where the ability to control the magnetization of materials at room temperature is highly desirable for developing next-generation spintronic devices.

Query # 5. In Figure 5(c), there are two sets of current-time curves at B = 0 and B = 0.2 T, which samples are they referring to respectively?

 Response: We apologize for the confusion caused to the reviewer. The sample referred in Figure 5(c) is Ni-10% doped ZnO. B = 0 (black) is the case when there is no magnetic field applied while B = 0.2 T (red) is the first run in magnetic field. Then, we turned off the magnetic field i.e., B = 0 (green), and again we turned on the magnetic field i.e., B = 0.2 T (blue).  We have now mentioned these details in the revised manuscript.

The revised response is highlighted in red on page # 10 and lines # 310-314.

Mistake:

1. Page 7 Line 231, Fig. 5(b), here it should be Fig. 4(b). Similar problem happens at Page 8 Line 240, that should be also Fig. 4.

Response: We apologize for the unintentional mistakes that are highlighted by the reviewer. We have now fixed these errors in the revised manuscript.

References:

1. Chu, Y.-L.; Young, S.-J.; Ji, L.-W.; Chu, T.-T.; Chen, P.-H. Synthesis of Ni-Doped ZnO Nanorod Arrays by Chemical Bath Deposition and Their Application to Nanogenerators. Energies 2020, 13, doi:10.3390/en13112731.
2. Park, S.; Jung, W.; Park, C. Role of Nickel Catalyst during the Growth of ZnO Nanowalls Investigated by Atom Probe Tomography. Jpn. J. Appl. Phys. 2013, 52, 25502, doi:10.7567/JJAP.52.025502.
3. Kazmi, J.; Ooi, P.C.; Goh, B.T.; Lee, M.K.; Wee, M.F.M.R.; Karim, S.S.A.; Raza, S.; Raza, A.; Mohamed, M.A. RSC Advances Bi-Doping Improves the Magnetic Properties of Zinc Oxide Nanowires †. RSC Adv. 2020, 10, 23297–23311, doi:10.1039/D0RA03816D.
4. Kazmi, J.; Ooi, P.C.; Raza, S.R.A.; Boon Tong, G.; Karim, S.S.A.; Samat, M.H.; Lee, M.-K.; Razip Wee, M.F.M.; Taib, M.F.M.; Mohamed, M.A. Evidence of Room Temperature Ferromagnetism in Vertically Aligned Bi-Co Co-Doped ZnO Nanowires. J. Phys. D. Appl. Phys. 2021, doi:10.1088/1361-6463/ac0b6f.
5. Kazmi, J.; Raza, S.R.A.; Ahmad, W.; Masood, A.; Jalil, A.; Mohd Raub, A.A.; Abbas, A.; Rafiq, M.K.S.; Mohamed, M.A. Free Carrier-Mediated Ferromagnetism in Nonmagnetic Ion (Bi-Li) Codoped ZnO Nanowires. Phys. Chem. Chem. Phys. 2023, 25, 14206–14218, doi:10.1039/d3cp00114h.
6. Kazmi, J.; Ooi, P.C.; Raza, S.R.A.; Goh, B.T.; Karim, S.S.A.; Samat, M.H.; Lee, M.K.; Mohd. Razip Wee, M.F.; Taib, M.F.M.; Mohamed, M.A. Appealing Stable Room-Temperature Ferromagnetism by Well-Aligned 1D Co-Doped Zinc Oxide Nanowires. J. Alloys Compd. 2021, 872, 159741, doi:10.1016/j.jallcom.2021.159741

Round 2

Reviewer 2 Report

The revised version is ready to publish.

Author Response

Dear Academic Editor,

We sincerely appreciate your time and effort in reviewing our manuscript. We are grateful for the valuable feedback provided by you.

Based on the thoughtful comments and suggestions, we have made significant revisions to the manuscript to enhance its clarity, scientific rigor, and overall quality. We believe that these changes have strengthened the presentation of our research findings and contributed to the advancement of the field.

Below, we have addressed each of the reviewer's comments:

* Title: please replace "Magneto transport" by "Magneto-Transport"
Response: Thank you for the suggestion. We have revised the title accordingly, replacing "Magneto transport" with "Magneto-Transport."
* section "3. Results and Discussion": please start the section by a phrase or two in which you briefly explain your work
Response: We appreciate the feedback. In response to this, we have added a brief introductory phrase to the "Results and Discussion" section, providing an overview of our work and setting the context for the subsequent discussion.
“Through a series of comprehensive characterizations and measurements, we explore the structural, magnetic, and magneto-transport behavior of the nanowires. Our study aims to shed light on the influence of Ni doping on the properties of ZnO nanowires, particularly focusing on the manifestation of soft magnetic behavior and its implications for potential spintronic applications. We begin by discussing the structural analysis, highlighting the morphology and crystalline structure of the nanowires. Subsequently, we delve into the magnetic properties, elucidating the room-temperature ferromagnetic behavior observed in the Ni-doped ZnO nanowires. Furthermore, we present the magneto-transport measurements, showcasing the negative magnetoresistance and its correlation with the magnetic behavior. The comprehensive analysis in this section contributes to our understanding of the unique properties of Ni-doped ZnO nanowires, opening avenues for their potential applications in spintronics and magnetic devices.”
The additional text is highlighted in red on page # 4 and lines # 168-179.
* Figure 1d: please provide a scale bar
Response: Thank you for pointing this out. We have now included a scale bar in Figure 1d to provide a visual reference for the dimensions presented in the image.
* replace "Zn++" by "Zn2+" or by "Zn+2" throughout the text (and keep it)
Response: We acknowledge the inconsistency in notation and appreciate the suggestion. Following the recommended notation, we have replaced "Zn++" with "Zn2+" throughout the manuscript. 
* Figure 3, molecule (upper left): details are not visible, please enlarge them
Response: We appreciate the comment. To address this issue, we have enlarged the details of the molecule in the upper-left corner of Figure 3, ensuring better visibility and clarity of the molecular structure. 

Best regards,

Corresponding Author