Synthesis of Copper, Silver, and Copper–Silver Powders by Hydrogen-Assisted Ultrasonic Spray Pyrolysis

Round 1

Reviewer 1 Report (New Reviewer)

Comments and Suggestions for Authors

1. The English version of the manuscript needs to be revised.

2. Makale, SEM ve EDS sonuçlarına dayanarak Cu-Ag çekirdek-kabuk yapılarının oluşumunu öne sürmektedir. bunun için TEM ve XRD sağlanmalıdır.
   Bu tür iddialar yumuşatılmalıdır.

   3. Application performansına ilişkin some referanslar, bu çalışmada deneysel verilerle desteklenmemektedir. Bu ifadeler, geleceğe yönelik önemle sınırlı olmalı ve kesinlikle literatürle desteklenmelidir.

   4.Section 3.4.2 is incorrectly titled 1:1 instead of 1:3 Cu–Ag ratio. 5. Some references are weakly related to the topic and should be reviewed. Authors are encouraged to consider citing additional USP-related studies focusing on similar synthesis pathways and parameter effects. 

Author Response

Dear Reviewer,

Thank you for your thorough and insightful comments. We have carefully addressed each of your concerns and made the necessary revisions to improve the manuscript. Please find our responses below:

1. The English language of the manuscript needs to be revised.

The manuscript has been thoroughly revised for English language, clarity, and academic style. Redundant explanations were removed, grammatical errors corrected, and several sections were rephrased to improve readability and coherence.

2. The manuscript proposes the formation of Cu–Ag core–shell structures based on SEM and EDS results. For such claims, TEM and XRD analyses must be provided. These types of claims should be softened.

All definitive claims regarding Cu–Ag core–shell structures have been softened. Structural interpretations are now explicitly limited to morphological and compositional trends inferred from SEM and semi-quantitative EDS, and the need for TEM and XRD for definitive confirmation is clearly stated in the Results, Discussion, and Conclusions.

3. Some statements regarding application performance are not supported by experimental data in this study. These statements should be limited to future relevance and must be supported by appropriate literature.

Statements related to application performance have been revised to emphasize literature-supported potential relevance rather than experimentally demonstrated performance. Appropriate references have been added, and such discussions are now clearly framed as prospective and future-oriented.

4. Section 3.4.2 is incorrectly titled as 1:1 instead of 1:3 Cu–Ag ratio.

The title of Section 3.4.2 has been corrected to accurately reflect the 1:3 Cu–Ag precursor ratio.

5. Some references are weakly related to the topic and should be reviewed. The authors are encouraged to cite additional USP-related studies focusing on similar synthesis pathways and parameter effects.

The reference list has been reviewed and strengthened by adding relevant ultrasonic spray pyrolysis (USP) studies addressing similar synthesis routes and parameter effects, while ensuring closer alignment between cited literature and the scope of the present work.

We appreciate your valuable feedback, which has helped us improve the clarity and structure of the manuscript. We hope that the revised version meets your expectations and can be published as soon as possible.

Best regards

Authors

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

This study explores the synthesis of Cu, Ag, and Cu-Ag powders using a combined ultrasonic spray pyrolysis (USP) and hydrogen reduction (HR) method. The work presents some interesting experimental results, several significant concerns regarding originality and methodology, however some mechanistic understanding and presentation need to be addressed before acception.

1. The introduction is insufficient, the number of references is inadequate, and some references are falsely cited. The introduction fails to clearly articulate the advantages of the existing ultrasonic spray pyrolysis (USP) technology over other synthesis methods, nor does it present the current state of research related to this method or material. It does not address the current status of relevant studies. The full texts of cited references [1], [6], [7], [8], [9], and [10] could not be located.

2. The nucleation-shell formation mechanism of the Cu-Ag bimetallic system has been extensively studied in wet chemical and electrodeposition fields. This research offers no novel mechanistic explanations or performance breakthroughs, merely reiterating known phenomena such as “particle refinement with increasing temperature.”

3. The paper lacks thermogravimetric analysis (TGA-DSC). While it mentions selecting copper nitrate trihydrate and silver nitrate based on their high solubility, well-defined thermal decomposition behavior, and widespread application, TGA-DSC is necessary to precisely determine the thermal decomposition temperature ranges of these precursors during the USP-HR process.

4. In Section 2.2, among the three synthesized particles, Cu was synthesized at four distinct temperatures to investigate the effect of synthesis temperature on particle size. Ag was synthesized at only two temperatures, but a control group was set up with H₂ addition to study the role of hydrogen reduction. This experiment did not include a control group without Cu in the absence of H₂, and the necessity of testing the three particles at these specific temperatures was not explained. Cu-Ag bimetallic powder was synthesized at a single temperature of 650°C without investigating temperature effects on bimetallic structure and properties, resulting in insufficient parameter variation.

5. TEM testing is absent. Section 3.4.1 mentions a “possible continuous silver shell layer.” Provide high-resolution TEM (HRTEM) images and selected area electron diffraction (SAED) patterns to directly demonstrate core-shell structure and crystallographic information.

6. XRD testing is absent. Without XRD data, how can the crystal structures and phase compositions of Cu, Ag, and Cu-Ag powders be confirmed solely based on EDS? For instance, how is the presence of oxides or other impurities ruled out? For Cu-Ag bimetallic powder, how is it determined whether it exhibits a solid solution, mechanical mixture, or core-shell structure?

7. Particle size analysis provides only the average particle size without key statistical parameters such as standard deviation or polydispersity index. Figures were generated using Excel's graphing function. EDS analysis reports only elemental mass fractions without error assessment for quantitative analysis, lacking data rigor, and figures are insufficiently clear.

8. The paper states that “hydrogen atmospheres typically yield high-purity but larger particles, while argon produces finer, more uniform particles.” Do the authors have detailed explanations regarding the particle growth mechanisms under different atmospheres?

9. Table 2 shows the 550°C sample contains 0.6 wt% Si, but its origin is not discussed.

10. Formatting errors:Line 68: Missing period at paragraph end. Line 117(a): [、] character appears before image. Lines 158 and 159: Image overlaps with heading section. Lines 179 and 159: Third-level headings 3.4.1 and 3.4.2 share identical text. Line 236: Citation format error. Line 279: Incorrect CO₂ notation.

Author Response

Dear Reviewer,

Thank you for your thorough and insightful comments. We have carefully addressed each of your concerns and made the necessary revisions to improve the manuscript. Please find our responses below:

This study explores the synthesis of Cu, Ag, and Cu-Ag powders using a combined ultrasonic spray pyrolysis (USP) and hydrogen reduction (HR) method. The work presents some interesting experimental results, several significant concerns regarding originality and methodology, however some mechanistic understanding and presentation need to be addressed before acception.

1. The introduction is insufficient, the number of references is inadequate, and some references are falsely cited. The introduction fails to clearly articulate the advantages of the existing ultrasonic spray pyrolysis (USP) technology over other synthesis methods, nor does it present the current state of research related to this method or material. It does not address the current status of relevant studies. The full texts of cited references [1], [6], [7], [8], [9], and [10] could not be located.

We agree with the reviewer. The introduction has been substantially rewritten.

All problematic references ([1], [6]–[10]) that were either inaccessible, incorrectly cited, or not directly relevant have been removed or replaced with peer-reviewed journal articles that explicitly address USP, spray pyrolysis, and Cu–Ag bimetallic systems. The reference list has been expanded accordingly.

2. The nucleation-shell formation mechanism of the Cu-Ag bimetallic system has been extensively studied in wet chemical and electrodeposition fields. This research offers no novel mechanistic explanations or performance breakthroughs, merely reiterating known phenomena such as “particle refinement with increasing temperature.”

We agree with the reviewer that nucleation and core–shell formation in Cu–Ag systems have been extensively studied in wet chemical and electrochemical synthesis routes. The present work does not aim to introduce new mechanistic explanations for these phenomena. Instead, the manuscript has been revised to clarify that the contribution of this study lies in demonstrating how known compositional tendencies of Cu–Ag systems manifest under gas-phase ultrasonic spray pyrolysis combined with hydrogen reduction. Overinterpretation of mechanistic novelty has been removed, and the discussion has been reframed to emphasize process-level insights rather than fundamental nucleation mechanisms.

3. The paper lacks thermogravimetric analysis (TGA-DSC). While it mentions selecting copper nitrate trihydrate and silver nitrate based on their high solubility, well-defined thermal decomposition behavior, and widespread application, TGA-DSC is necessary to precisely determine the thermal decomposition temperature ranges of these precursors during the USP-HR process.

We agree with the reviewer that thermogravimetric and calorimetric analyses are valuable tools for precisely determining precursor decomposition behavior. In the present study, TGA-DSC measurements were not performed. The selection of copper nitrate trihydrate and silver nitrate, as well as the applied temperature range, was based on well-established decomposition characteristics reported in the literature. The manuscript has been revised to clarify that thermal decomposition behavior was inferred from prior studies rather than experimentally determined. A statement has also been added to the Conclusions to indicate that future work will incorporate TGA-DSC analysis to further refine the correlation between precursor decomposition and particle formation during USP–HR processing.

4. In Section 2.2, among the three synthesized particles, Cu was synthesized at four distinct temperatures to investigate the effect of synthesis temperature on particle size. Ag was synthesized at only two temperatures, but a control group was set up with H₂ addition to study the role of hydrogen reduction. This experiment did not include a control group without Cu in the absence of H₂, and the necessity of testing the three particles at these specific temperatures was not explained. Cu-Ag bimetallic powder was synthesized at a single temperature of 650°C without investigating temperature effects on bimetallic structure and properties, resulting in insufficient parameter variation.

The experimental design was structured to address different process-related questions for each material system while maintaining stable operating conditions in the continuous USP–HR reactor. For copper powders, multiple synthesis temperatures (550–700 °C) were selected to systematically evaluate the influence of temperature on particle size evolution and reduction efficiency. For silver powders, a reduced temperature range was chosen, and the primary variable was the gas atmosphere, in order to isolate the role of hydrogen-assisted reduction compared to thermally driven decomposition under argon.

In the case of Cu–Ag bimetallic powders, synthesis was conducted at a fixed temperature of 650 °C, which was identified as a stable intermediate condition based on the monometallic Cu and Ag experiments. This approach allowed the influence of precursor molar ratio on particle morphology and oxidation behavior to be examined without introducing additional temperature-related effects.

5. TEM testing is absent. Section 3.4.1 mentions a “possible continuous silver shell layer.” Provide high-resolution TEM (HRTEM) images and selected area electron diffraction (SAED) patterns to directly demonstrate core-shell structure and crystallographic information.

Unfortunately, no funding  for this work!

5. XRD testing is absent. Without XRD data, how can the crystal structures and phase compositions of Cu, Ag, and Cu-Ag powders be confirmed solely based on EDS? For instance, how is the presence of oxides or other impurities ruled out? For Cu-Ag bimetallic powder, how is it determined whether it exhibits a solid solution, mechanical mixture, or core-shell structure?

Answer 5. and 6.: We agree with the reviewer that transmission electron microscopy (TEM/HRTEM/SAED) and X-ray diffraction (XRD) are essential techniques for confirming internal particle structure, crystallographic information, and phase composition. In the present study, TEM and XRD analyses were not performed. The manuscript has therefore been revised to remove any definitive claims regarding core–shell formation, solid-solution behavior, or phase purity.

Structural interpretations are now explicitly limited to morphological observations from SEM and elemental distribution trends obtained by EDS, which are treated as semi-quantitative. The possibility of oxide phases or alternative structural configurations cannot be conclusively excluded based on EDS alone, and this limitation is now clearly stated in the revised manuscript. Future work will incorporate XRD and TEM-based analyses to resolve crystallographic structure, phase composition, and internal particle architecture of USP-derived Cu, Ag, and Cu–Ag powders.

7. Particle size analysis provides only the average particle size without key statistical parameters such as standard deviation or polydispersity index. Figures were generated using Excel's graphing function. EDS analysis reports only elemental mass fractions without error assessment for quantitative analysis, lacking data rigor, and figures are insufficiently clear.

We thank the reviewer for highlighting the importance of statistical rigor in particle size and compositional analysis. The manuscript has been revised to improve the transparency and presentation of the data. Particle size distributions were obtained from SEM images by measuring a minimum of 100 particles per sample using ImageJ software, and average particle diameters are now reported together with standard deviation to reflect size dispersion. Figure captions and related text have been updated accordingly.

With respect to compositional analysis, EDS data are now explicitly described as semi-quantitative, and the inherent limitations of EDS for precise quantitative analysis and error estimation are clarified in the manuscript. The interpretation of elemental mass fractions has been revised to avoid overstatement, and figures have been improved for clarity and readability. These revisions enhance data rigor while remaining consistent with the scope of the experimental techniques employed.

8. The paper states that “hydrogen atmospheres typically yield high-purity but larger particles, while argon produces finer, more uniform particles.” Do the authors have detailed explanations regarding the particle growth mechanisms under different atmospheres?

We thank the reviewer for this comment. A detailed explanation of the observed particle size differences under hydrogen-containing and argon atmospheres has been included and clarified in the Discussion section. The interpretation is provided at a process and phenomenological level, based on differences in reduction kinetics, nucleation rates, and particle growth behavior.

9. Table 2 shows the 550°C sample contains 0.6 wt% Si, but its origin is not discussed.

We thank the reviewer for pointing this out. The trace silicon content (0.6 wt%) detected in the copper sample synthesized at 550 °C has now been addressed in the manuscript. This minor contribution is attributed to incidental contamination from the quartz reactor tube or sample handling during high-temperature processing, which is commonly observed in spray pyrolysis systems.

10. Formatting errors:Line 68: Missing period at paragraph end. Line 117(a): [、] character appears before image. Lines 158 and 159: Image overlaps with heading section. Lines 179 and 159: Third-level headings 3.4.1 and 3.4.2 share identical text. Line 236: Citation format error. Line 279: Incorrect CO₂ notation.

Thank you for noting this errors. It has been corrected.

We appreciate your valuable feedback, which has helped us improve the clarity and structure of the manuscript. We hope that the revised version meets your expectations and can be published as soon as possible.

Best regards

Authors

 

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

In this paper, the synthesis of copper, silver and copper-silver powder by hydrogen-assisted ultrasonic spray pyrolysis is studied. The experimental design is systematic and the data support is relatively sufficient, but there is still room for optimization and perfection.

1. The application of copper, silver and copper-silver bimetallic systems in the fields of electronics and catalysis is mentioned in this paper, but the pain points of current research are not elaborated.
2. Although the existing references cover the fields of metal powder synthesis, bimetallic properties and so on, there is a lack of direct related research summary on the application of USP-HR method in copper-silver powder synthesis.
3. The experiment was only characterized by SEM and EDS, which could not fully reflect the crystal structure, phase composition and other key properties of the powder. XRD analysis can be supplemented to confirm the crystal structure of the metal, or XPS analysis can be used to detect the surface oxidation state.
4. Deepen the analysis of the results, explain the experimental phenomena with the help of thermodynamic theory, and enhance the persuasiveness.

Author Response

Dear Reviewer,

Thank you for your thorough and insightful comments. We have carefully addressed each of your concerns and made the necessary revisions to improve the manuscript. Please find our responses below:

In this paper, the synthesis of copper, silver and copper-silver powder by hydrogen-assisted ultrasonic spray pyrolysis is studied. The experimental design is systematic and the data support is relatively sufficient, but there is still room for optimization and perfection.

1. The application of copper, silver and copper-silver bimetallic systems in the fields of electronics and catalysis is mentioned in this paper, but the pain points of current research are not elaborated.

We expanded the Introduction to explicitly describe key limitations in current Cu/Ag/Cu–Ag powder applications (e.g., oxidation susceptibility, agglomeration/sintering, surface contamination in wet routes, and scalability/reproducibility challenges) and clarified how USP–HR addresses these bottlenecks.

1. Although the existing references cover the fields of metal powder synthesis, bimetallic properties and so on, there is a lack of direct related research summary on the application of USP-HR method in copper-silver powder synthesis.

We strengthened the literature review by adding a focused summary of prior USP/spray-based Cu, Ag, and Ag–Cu reports and explicitly stating the remaining gap in systematic parameter–morphology–stability relationships under hydrogen-assisted conditions.

1. The experiment was only characterized by SEM and EDS, which could not fully reflect the crystal structure, phase composition and other key properties of the powder. XRD analysis can be supplemented to confirm the crystal structure of the metal, or XPS analysis can be used to detect the surface oxidation state.

We revised the manuscript to clearly limit structural claims to SEM/EDS-based trends and explicitly state that definitive phase/crystallographic identification requires complementary techniques; XRD and TEM/HRTEM are included as planned future work, and XPS has been added as an option to assess surface oxidation states.

1. Deepen the analysis of the results, explain the experimental phenomena with the help of thermodynamic theory, and enhance the persuasiveness.

We expanded the Discussion with a concise thermodynamic rationale describing why reducing (H₂-containing) vs. inert (Ar) atmospheres shift reaction pathways and influence nucleation/growth tendencies, while keeping interpretations at a qualitative process level consistent with the available characterization.

 

We appreciate your valuable feedback, which has helped us improve the clarity and structure of the manuscript. We hope that the revised version meets your expectations and can be published as soon as possible.

Best regards

Authors

Round 2

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

The revised version is satisfied with well addressing issues raised by referee.   

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors Cu, Ag, and Cu–Ag powders were synthesized using ultrasonic spray pyrolysis (USP) combined with hydrogen reduction. The study examined the effects of reduction temperature, gas atmosphere, and precursor ratio on the resulting powders. While the article demonstrates practical relevance, I find the dataset limited and the theoretical contribution insufficient. Therefore, I cannot recommend acceptance at this time. 1) Why were only the 1:1 and 1:3 ratios of CuAg powder prepared? 2) The study relies solely on energy-dispersive X-ray spectroscopy (EDS) to assess powder purity. Given EDS's limited accuracy, a 100% result does not conclusively confirm purity. Furthermore, all four EDS images display uncalibrated peaks; clarification is needed regarding the elements or compounds these peaks represent. 3) The use of ImageJ on just over 100 particles provides too small a sample to characterize particle size distribution. Additional testing methods are suggested to strengthen the analysis.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors present an interesting study on the synthesis of Cu, Ag, and Cu-Ag composite powders using ultrasonic spray pyrolysis. The work is promising and aligns well with the scope of this journal. However, the manuscript in its current form requires significant revisions to meet the journal's high standards for clarity, data presentation. The following specific points should be addressed to strengthen the manuscript before it can be considered for publication.

The precursor information is currently not provided in the main text other than the methods. Figure 1 is not adequately integrated into the main text and lacks proper labeling.

To substantiate the claim of successful Cu-Ag composite formation and to evaluate the homogeneity of the mixture, SEM-EDS elemental mapping for both Cu and Ag should be provided. This is critical evidence for the core premise of the work.

The current SEM images contain instrument, ecific text and markings (e.g., scale bars with manufacturer details). To maintain a professional and consistent presentation, these should be processed and removed, following the visual standard of other publications in this journal.

The inclusion of TEM analysis is highly recommended. HRTEM images would provide evidence of crystallinity, lattice fringes, and potential core-shell or alloyed structures. Also provide XRD of these NCs.

To demonstrate the practical utility and enhanced properties of the synthesized bimetallic powders, an application study is strongly advised. Given the known plasmonic properties of Cu and Ag, evaluating their performance as substrates for Surface-Enhanced Raman Spectroscopy (SERS) would be a highly relevant and convincing demonstration of their applicability.

The quality of the figures requires significant improvement.

In Figure 2, text appears to be merged with the image, making it difficult to read. This must be corrected.

Figures 2 and 3 are not properly labeled on the images themselves (e.g., parts a, b, c). Every sub-figure must be clearly labeled.

All figure captions need to be self-explanatory. For example, the caption for Figure 3 should be expanded to something like: "Figure 3: Visual observation of the precursor solution color change during copper nanoparticle synthesis, indicating the reduction from blue Cu²⁺ ions to reddish-brown metallic Cu nanoparticles." Similar detail should be applied to all captions.

The title is descriptive but could be more concise and impactful. It should more directly capture the key synthesis method and the unique aspect of the materials produced. For example: "One-Pot Synthesis of Cu, Ag, and Bimetallic Cu-Ag Powders by Hydrogen-Assisted Ultrasonic Spray Pyrolysis." he phrase "through Hydrogen Reduction" is slightly ambiguous and could be misinterpreted. Rephrasing it to "via Hydrogen-Assisted Reduction" or "using Hydrogen as a Reducing Agent" would improve clarity.

Please ensure consistency in formatting throughout the manuscript (e.g., "600 °C" vs. "700°C".

Reviewer 3 Report

Comments and Suggestions for Authors

Unfortunately, the manuscript is poorly written and difficult to understand. Furthermore, the novelty and scientific soundness of this research are quite limited. Numerous studies in the literature have already reported on the use of the USP-HR method to synthesize various nanoparticles, including those based on noble metals and their nanocomposites. Furthermore, how does this work differ from the authors' earlier and more in-depth study DOI: 10.1016/j.cep.2014.06.002?
1.    The introduction does not fully address the research topic; it contains many sentences that are irrelevant to the aim of this manuscript. It should be significantly expanded to include a thorough review of the available literature on the topic. Additionally, the authors should demonstrate the novelty of their work.
2.    The Materials and Methods section is weakened by the inclusion of unnecessary figures 1 и 3. 
3.    The statement in lines 73–75 is misleading as it suggests that other commercially available Cu(II) and Ag(I) salts cannot be used solely because of their poor water solubility and thermal decomposition. Supporting data demonstrating the effect of solubility and thermal decomposition on the synthesis outcome is required for this claim (or at least references to works where this has been demonstrated). 
4.    The text lacks references to Figure 2 and Table 1.
5.    Line 79: What do the authors mean by 'copper and silver solutions'? 
6.    Figure 2: the stock solutions are neither labeled nor integrated into the overall reactor schematic.
7.    For better readability, the experimental procedure (lines 86-91) should be described in a consistent and sequential manner, integrating all relevant equipment parameters at each corresponding step, rather than separating the general description from the technical details.
8.    The model and type of atomizer and furnace used in this work should be specified.
9.    The preparation and composition for solutions S1-S4 are not provided in the text.
10.    The results section lacks many important analyses that would prove the composition and structure of the obtained materials. The vast majority of figures are unclear due to either the presence of a metadata bar or an inappropriate choice of measurement units. So,  to enhance the clarity of the images, the SEM images should be presented without the metadata bar and the scale bars should be made more prominent.
11.    Paragraph 3.1.2: As this statement is temperature-dependent, it is unnecessary to emphasise particle size variation in a separate clause. The paragraphs 3.1.1 and 3.1.2 can be consolidated.
12.    Fig5: For clear data representation, the particle size data should be presented as a histogram (percentage vs. diameter). The plot name should be removed to reduce clutter. Furthermore, for the complex, potentially non-normal distributions observed, the median particle size is a more robust metric than the average particle size and should be reported. All particle size distribution plots should be revised according to the same criteria.
13.    Please verify the correctness of mathematical operations in the table 2. It doesn’t get 100% when all the columns are combined. Additionally, the sources of all detected elements should be identified.
14.    paragraph 3.2 (line 138): Mismatched heading. This section discusses SEM.
15.    Figures 7, 9-11 – All peaks should be labeled.
16.    The discussion section has many major issues. First, literature references should be verified, as the referred information is presented incorrectly, while the literature survey should be conducted more comprehensively. Second, this section struggles with a large number of unsupported statements. References or experimental data are not provided to do such strong claims as, for instance, increasing of a particle size at higher temperature of synthesis. On the contrary, some important aspects of the manuscript (e.g., faster nucleation when synthesize Ag-rich samples) have not been discussed. However, this manuscript needs improvement in many areas, as discussed below.
17.    Lines 213-215: For the characterization of SPR, it would be prudent to provide uv-vis absorption spectra. The reddish hue of the solution is not definitive evidence of SPR and requires spectroscopic validation.
18.    Lines 215-216: The SEM images and the corresponding size distributions indicate that the vast majority of the particles are sub-micron or micron in scale. The term "Nanoparticles" appears to be inaccurate for describing this material. Although the distributions show a minor fraction of nanoscale particles, the system is highly polydisperse and is predominantly composed of larger particles.
19.    Are there XRD data to study the structure and crystallinity of the samples?
20.    Lines 220-221: This statement requires an additional analysis or citation of relevant literature. Moreover, analysis of the SEM images reveals noticeable particle coalescence.
21.    Lines 222-223: This statement should be supported by some strong evidences.
22.    Lines 223-224: This interpretation should be re-evaluated through a more careful analysis of the provided SEM data.
23.    Line 224: Please explain why the presence of hydrogen leads to formation of 'the smaller and more uniform nanoparticles' if according to the SEM data particles with the same size were obtained? Additionally, claims that H2 accelerates reduction kinetics and promotes burst nucleation (lines 224-225) should be supported by some strong evidence or citation of relevant literature.
24.    Lines 225-226: As is well known, slower kinetics lead to the formation of particles with a more uniform size. Consequently, should one expect the particle size distributions in this manuscript to be more uniform?
25.    Please check the accuracy of reference 11, as it does not seem to confirm the previous statement.
26.    Line 230-231: This statement should be supported by some strong evidence like XRD data. Furthermore, does this statement imply that the poly-disperse, mixed Cu-CuO particles were obtained in this manuscript?
27.    Please verify the accuracy of reference 12. The cited work describes the synthesis of CuO nanoparticles but lacks information supporting this specific statement.
28.    Sentence at lines 231-232 is redundant, as it repeats the meaning of the previous one (lines 221-223).
29.    Lines 233-234: The discussion in this paragraph needs improvement and broader literature citation.
30.    Check the number of the paragraph 3.2 (lines 235 and 260)
31.    Line 239: As is well-known, silver can be easily reduced to Ag NPs using hydrogen, resulting in stable particles. Thus, is this statement a specific feature of the chosen synthesis method or chosen material?
32.    Lines 239-241: This statement requires a supporting reference.
33.    Lines 241-243: Please explain the mechanism of this phenomenon.
34.    Lines 243-245: For better readability, this sentence should be placed after the discussion on the necessity of a hydrogen-assisted atmosphere.
35.    Lines 249-252: Are there any experimental data or references to support these statements?
36.    Does the autocatalytic deposition occur in the gas phase? What is the evidence that this mechanism accurately describes the experimental data?
37.    Lines 258-259: what is the potential reason for this observation?
38.    Figure 11 shows that one type of particle is deposited on another, indicating that the structure is not core-shell. Furthermore, Figure 10 reveals that the sharp-edged particles are localized in specific regions rather than forming a uniform coating, which is uncharacteristic of core-shell structures. If this manuscript claims the successful synthesis of core-shell particles, this claim requires more substantial evidence.
39.    The claim that Ag-rich shell surrounding a Cu core requires supporting experimental data or, at least, references.
40.    Line 268: It is well established that a noble metal shell will only protect a copper core from oxidation if the shell is uniform and robust. Is there experimental leaching data to support this claim?
41.    Lines 271-272: The structural aspects are scarcely addressed in this manuscript, and the presented data indicate that the obtained particles were not of high purity. This statement overestimates the advantages of the work.
42.    Lines 276-277: What is the potential reason for increasing the tendency for surface oxidation?
43.    Line 278: How was structural stability observed?
44.    Line 279: Potential catalytic performance hasn't been addressed in this manuscript.
45.    The manuscript lacks a discussion about of the challenges associated with synthesizing Cu-Ag powders.

So, the article has serious flaws and additional experiments needed. Thus, I cannot recommend this paper for publication.