Control of Manganese Oxide Hybrid Structure through Electrodeposition and SILAR Techniques for Supercapacitor Electrode Applications

Round 1

Reviewer 1 Report

The works seems to be interesting. However, teh results and discussion should be improved. I would like to provide the following suggestion to improve the quality of this manuscript.

1.      The authors claimed that the Mn3O4 formation is achieved and even in the stoichiometric balance equation, the authors have derived the balance equation for Mn3O4. But throughout the manuscript, in many places, the sample is mentioned as MnOx. It will be good if the author use Mn3O4 formula everywhere. Otherwise it may confuse the authors.

2.      FESEM micrographs for EPD-A, and EPD-S are given with 1 um scale bar, whereas other samples are given in 2 or 20 um scale bar which makes the readers to find difficulties in resolution. The author may provide high resolution images with same level of magnification or same level of scale bar to compare the morphology variation with the variation in the experimental process.

3.      Subscript, superscript and acronyms should be carefully checked throughout this manuscript.

4.      Did the authors tried to check the CV performances at higher scan rate? The authors mentioned that the cyclic voltammetry was measured at a scan rate range from 5 to 100 mV s-1. However the results are not included. The authors may include CVs for other scan rates also.

5.      Did the authors evaluate the GCD performances at other current densities?. The authors have written as Galvanostatic charge–discharge (GCD) was measured at various current densities from 141 0.1 mA cm-2 to 1 mA cm-2. However the results are not included. The authors may include those GCD curves.

6.      In the text, including abstract, introduction, discussion and conclusion sections the authors have written as they have done the GCD measurement at 0.1mA/cm2. But in figure 5, it is mentioned as 0.5 mA/cm2. The authors should correct that.

 

7.      The authors have done the stability test upto 500 number of cycles, which is very less. The cycle stability/capacity retention of HYB-A and EPD-S samples are very less compared to the available literatures. In which way the developed samples are comparable with the presently available materials. 

8. References should be improved by refereing recent research artilces.

 

Author Response

Response to Reviewer 1 Comments

 

Point 1: The authors claimed that the Mn₃O₄ formation is achieved and even in the stoichiometric balance equation, the authors have derived the balance equation for Mn₃O₄. But throughout the manuscript, in many places, the sample is mentioned as MnOx. It will be good if the author use Mn₃O₄ formula everywhere. Otherwise it may confuse the authors.

 

Response 1: We have revised the manuscript to mention manganese oxide and Mn₃O₄ instead of MnO_x in the appropriate places.

 

 

Point 2: FESEM micrographs for EPD-A, and EPD-S are given with 1 um scale bar, whereas other samples are given in 2 or 20 um scale bar which makes the readers to find difficulties in resolution. The author may provide high resolution images with same level of magnification or same level of scale bar to compare the morphology variation with the variation in the experimental process.

 

Response 2: We have revised the FE-SEM images to be at the same magnification with the same scale bar of 1 um for easy comparison. Low magnification SEM images of all samples are shown in Figure S1.

 

Point 3: Subscript, superscript and acronyms should be carefully checked throughout this manuscript.

Response 3: Thank you for bringing this to our attention. We have thoroughly reviewed the manuscript for subscript, superscript, and acronyms, and made necessary corrections to ensure consistency and accuracy throughout the document.

 

Point 4: Did the authors tried to check the CV performances at higher scan rate? The authors mentioned that the cyclic voltammetry was measured at a scan rate range from 5 to 100 mV s-1. However the results are not included. The authors may include CVs for other scan rates also.

 

Response 4: We have included all of the CV results in the supplementary information (Figure S2) and revised Figure 4 to include the CV curves of EPD-S and HYB-A electrodes at various scan rates ranging from 5 to 100 mV/s (Figure 4(c,d). The explanation of Figure 4(c,d) is also added to the revised manuscript.

“Figure 4(c, d) displays the CV curves of the EPD-S and HYB-A electrodes at various scan rates. Even at the higher scan rate of up to 100 mV s^-1, both electrodes maintained their semi-rectangular CV curves, indicating the stability of the electrodes. The redox peaks were observed to be more shifted in the EPD-S electrode than in the HYB-A electrode, sug-gesting that the redox reaction on the surface of the EPD-S required longer time for ion diffusion to facilitate the redox reaction [31]. The CV curves of each electrode studied in this work are shown in Figure S2.”

 

Point 5: Did the authors evaluate the GCD performances at other current densities?. The authors have written as Galvanostatic charge–discharge (GCD) was measured at various current densities from 141 0.1 mA cm-2 to 1 mA cm-2. However the results are not included. The authors may include those GCD curves.

 

Response 5: We have included the GCD results of each electrode studied in this work in the supplementary information (Figure S3) and revised Figure 5 to include the GCD curves of EPD-S and HYB-A electrodes at various current densities from 0.1 to 1 mA/cm² (Figure 5(c,d)). The explanation of Figure 5(c,d) is also added to the revised manuscript.

“Figure 5(c, d) displayed the GCD curves of the EPD-S and HYB-A electrodes at current densities ranging from 0.1 mA cm^-2 to 1.0 mA cm^-2. An obvious redox peak was observed in both electrodes at the low current density. The semi-symmetrical triangular shape of the GCD curves was still retained even at the higher current density of 1 mA cm^-2, indicating the good stability of the electrode performance. The GCD curves of each electrodes studied in this work at various current densities are shown in Figure S3.”

 

 

Point 6 : In the text, including abstract, introduction, discussion and conclusion sections the authors have written as they have done the GCD measurement at 0.1mA/cm². But in figure 5, it is mentioned as 0.5 mA/cm². The authors should correct that.

 

Response 6: We have revised Figure 5 to ensure that the GCD measurement is listed at 0.1 mA/cm².

 

Point 7 :  The authors have done the stability test upto 500 number of cycles, which is very less. The cycle stability/capacity retention of HYB-A and EPD-S samples are very less compared to the available literatures. In which way the developed samples are comparable with the presently available materials.

 

Response 7: We have extended the cycling stability test to 1500 cycles for the EPD-S and HYB-A electrodes. They retained their specific capacitance almost at the same value as at 500 cycles (approximately 65% and 56%, respectively).

 

Point 8 :  References should be improved by refereing recent research artilces.

 

Response 8: We have added the recently published works you suggested to the manuscript as shown in the list of additional references below. Accordingly, the introduction section has been revised slightly.

 

List of additional references.

1. Qiao, Y.; Sun, Q.; Xi, J.; Cui, H.; Tang, Y.; Wang, X. A modified solvothermal synthesis of porous Mn3O4 for supercapacitor with excellent rate capability and long cycle life. Journal of alloys and compounds 2016, 660, 416-422.
2. Yang, M.; Ning, H.; Xiao, L.; Cui, F.; Zhang, F. Mn3O4/MnS heterostructure for electrode and asymmetric supercapacitor under high charge/discharge current. Electrochimica Acta 2022, 424, 140630.
3. Xiong, C.; Zhang, Y.; Xu, J.; Dang, W.; Sun, X.; An, M.; Ni, Y.; Mao, J. Kinetics process for structure-engineered integrated gradient porous paper-Based supercapacitors with boosted electrochemical performance. Nano Research 2023, 1-9.
4. Luo, L.; Lan, Y.; Zhang, Q.; Deng, J.; Luo, L.; Zeng, Q.; Gao, H.; Zhao, W. A review on biomass-derived activated carbon as electrode materials for energy storage supercapacitors. Journal of Energy Storage 2022, 55, 105839.
5. Peçenek, H.; Dokan, F.K.; Onses, M.S.; Yılmaz, E.; Sahmetlioglu, E. Outstanding supercapacitor performance with intertwined flower-like NiO/MnO2/CNT electrodes. Materials Research Bulletin 2022, 149, 111745.
6. Athanasiou, M.; Yannopoulos, S.N.; Ioannides, T. Biomass-derived graphene-like materials as active electrodes for supercapacitor applications: a critical review. Chemical Engineering Journal 2022, 446, 137191.
7. Karatum, O.; Yildiz, E.; Kaleli, H.N.; Sahin, A.; Ulgut, B.; Nizamoglu, S. RuO2 Supercapacitor Enables Flexible, Safe, and Efficient Optoelectronic Neural Interface. Advanced Functional Materials 2022, 32, 2109365.
8. Ramasubramanian, B.; Chinglenthoiba, C.; Huiqing, X.; Xiping, N.; Hui, H.K.; Valiyaveettil, S.; Ramakrishna, S.; Chellappan, V. Sustainable Fe-MOF@ carbon nanocomposite electrode for supercapacitor. Surfaces and Interfaces 2022, 34, 102397.
9. Peng, Y.; Yuan, W.; Liu, X.; Xie, P.; Yang, F.; Zhao, H.; Lu, D.; Yin, Y.; Wu, Z. All-in-one integration of polyaniline-polyvinyl alcohol electrode/electrolyte interface for tailorable solid-state supercapacitors. Journal of Energy Storage 2023, 61, 106701.
10. Chi, H.Z.; Wu, Y.Q.; Shen, Y.K.; Zhang, C.; Xiong, Q.; Qin, H. Electrodepositing manganese oxide into a graphene hydrogel to fabricate an asymmetric supercapacitor. Electrochimica Acta 2018, 289, 158-167, doi:10.1016/j.electacta.2018.09.025.
11. Beknalkar, S.; Teli, A.; Bhat, T.; Pawar, K.; Patil, S.; Harale, N.; Shin, J.; Patil, P. Mn3O4 based materials for electrochemical supercapacitors: Basic principles, charge storage mechanism, progress, and perspectives. Journal of Materials Science & Technology 2022, 130, 227-248.
12. Wang, K.; Zhang, Z.; Cheng, S.; Han, X.; Fu, J.; Sui, M.; Yan, P. Precipitate-stabilized surface enabling high-performance Na0. 67Ni0. 33-xMn0. 67ZnxO2 for sodium-ion battery. eScience 2022, 2, 529-536.
13. Lee, H.-J.; Noor, N.; Gumeci, C.; Dale, N.; Parrondo, J.; Higgins, D.C. Understanding the Impact of the Morphology, Phase Structure, and Mass Fraction of MnO2 within MnO2/Reduced Graphene Oxide Composites for Supercapacitor Applications. The Journal of Physical Chemistry C 2022, 126, 13004-13014..
14. Zhang, M.; Chen, Y.; Yang, D.; Li, J. High performance MnO2 supercapacitor material prepared by modified electrodeposition method with different electrodeposition voltages. Journal of Energy Storage 2020, 29, 101363.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments: In a whole, This work is meaningful and the representation is comprehensive. However, there are still some minor issues need to be addressed before possible publication.

1. There is an issue with the format of the scanning electron microscope image.

2. The scanning electron microscopy of different samples should be compared at the same magnification.

3. Electrochemical testing is too simple, lacking cyclic voltammetry curves at different scanning rates and constant current charge discharge curves at different current densities.

4. For supercapacitors, a long cycle life is an important indicator. 500 cycles are not sufficient to reflect the cycling stability of the electrode material of the supercapacitor, and it is necessary to test the cycling stability under longer cycles.

5. Some recent work in the field should be cited to draw more readers’ attention. Such as Nano Research, 2023, https://doi.org/10.1007/s12274-023-5694-y; eScience 2 (2022) 529-536; 

 Minor editing of English language required

Author Response

Response to Reviewer 2 Comments

Point 1: There is an issue with the format of the scanning electron microscope image.

 

Response 1: The FE-SEM images have been revised so that the inset image has its own scale bar and is not confused with the scale bar of the main images.

 

Point 2: The scanning electron microscopy of different samples should be compared at the same magnification.

 

Response 2: The FE-SEM images have been revised to be at the same magnification and have the same scale bar at 1 um. Low magnification SEM images of all samples are shown in Figure S1.

 

Point 3: Electrochemical testing is too simple, lacking cyclic voltammetry curves at different scanning rates and constant current charge discharge curves at different current densities.

 

Response 3: The CV and GCD curves of all samples measured at various scan rates and current densities were included in the supplementary information (Figures S2, S3), while we also revised Figures 4 and 5 to include the CV and GCD curves of EPD-S and HYB-A electrodes at various scan rates and current densities as shown in Figures 4(c,d) and 5(c,d).

 

Point 4: For supercapacitors, a long cycle life is an important indicator. 500 cycles are not sufficient to reflect the cycling stability of the electrode material of the supercapacitor, and it is necessary to test the cycling stability under longer cycles.

 

Response 4: We have extended the cycling stability test to 1500 cycles for the EPD-S and HYB-A samples. They retained their specific capacitance almost at the same value as at 500 cycles (approximately 65% and 56%, respectively).

 

Point 5: Some recent work in the field should be cited to draw more readers’ attention. Such as Nano Research, 2023, https://doi.org/10.1007/s12274-023-5694-y; eScience 2 (2022) 529-536;

 

Response 5: We have added the recently published works you suggested to the manuscript..

9. Xiong, C.; Zhang, Y.; Xu, J.; Dang, W.; Sun, X.; An, M.; Ni, Y.; Mao, J. Kinetics process for structure-engineered integrated gradient porous paper-Based supercapacitors with boosted electrochemical performance. Nano Research 2023, 1-9.

19. Wang, K.; Zhang, Z.; Cheng, S.; Han, X.; Fu, J.; Sui, M.; Yan, P. Precipitate-stabilized surface enabling high-performance Na0. 67Ni0. 33-xMn0. 67ZnxO2 for sodium-ion battery. eScience 2022, 2, 529-536.

 

 

Author Response File: Author Response.pdf