Synthesis of ZnO Flakes on Flexible Substrate and Its Application on Ethylene Sensing at Room Temperature
Round 1
Reviewer 1 Report
Dear Editor,
Please, find in attach my review about this paper.
cordially
reviewer
Comments for author File: 
Comments.pdf
Author Response
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Author Response File: Author Response.pdf
Reviewer 2 Report
This paper reports the synthesis and ethylene sensing performance of ZnO flakes. The experimental data are abundant. I think this paper can be published after revision.
The sensitivity can be compared with previous reported results. The stability can be demonstrated. The selectivity can be investigated. The sensing mechanism illustration can be polished. Some relevant paper can be cited, such as Nano Energy 2017, 31, 37-48; Sensors and Actuators B: Chemical 2016, 222, 78-86; ACS Applied Materials & Interfaces 2015, 7, 10482-10490.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The author carefully presented the steps procedure of how the sensor was fabricated. He has also put a lot of effort into its morphological and chemical identification utilizing many specialized equipments like X-ray, FTIR, SEM-EDS, etc. Nevertheless, there are a few minor aspects related to the measurement part that should be clarified:
At lines, 77-78 is written: "The ethylene gas was injected into the chamber and ..."
Which chamber: Gas Chamber of Sample Chamber?
At line 78-79 is written:" .. was measured by Picotest M3500A digital multimeter."
What was the measurement current value for each sample?
At line 81 is written:" response (S) to ethylene gas was defined as [7] "
Shall it be " response (S) to ethylene gas was defined as in equation (1) "
At line 191 is written: " ... of ethylene gas at 29 and 50 ppm concentration,.."
Should be said more precisely: "... of ethylene gas at 29 and 50 ppm concentration for 15 minutes exposure time,.."
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
I recommend that this manuscript will be accepted after text editing.
Title: 'Synthesis of ZnO Flakes on Flexible Substrate and Its Application on Ethylene Sensor': To be rewritten
Abstract:
'ethylene concentration monitoring plays an important role in agricultural field': To be rewritten
'One of the techniques that can be used to 15 detect ethylene concentration is sensing method': To be rewritten
Author Response
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Author Response File: Author Response.pdf
Reviewer 5 Report
Comments to the Author
Sholehah et al. present a ZnO-based flexible sensor. ZnO nanostructures have already been used as sensors multiple times in the literature, for many applications. In this work, the authors used the nanomaterial to identify the presence of ethylene gas. One of the key advantages of this sensor is that it can be applied at room temperature. Though the work is comprehensively performed, I do recommend its publication in Chemosensors only after some corrections have been made.
My main concerns are as follows:
Consequent additions and rephrasing should be made to the Introduction, which is too short in the present form. More basics on sensing devices should be added, and a basic overview of similar works in the literature should be given. A comparison with other sensors based on ZnO nanostructures should be added as well (Weber et al, Journal of Materials Chemistry A 7, 14, 8107, 2019 ; Barecca et al, Sensors and Actuators B: Chemical, 149, 1, 1, 2010).
Is there a real benefit of having a flexible substrate for this application? Seems unnecessary for the application given.
One of the main advantages of this sensor is that it can be efficiently used at room temperature. This fact should be more highlighted in the manuscript.
The authors prepared the active ZnO layers on PET substrates. It is known from the literature that consequent fractures and mechanical strain can result when such inorganic materials are prepared on flexible polymers. Please comment on that using recent literature (Chawla et al, Nanomaterials 9 (1), 88, 2019)
The authors used a 2 hours long electrodeposition process for the preparation of the ZnO layer. Why did they use this technique in particular? A PVD or low temperature CVD/ALD methods seem more appropriate. Please justify the use of the route.
The authors show the efficient detection of ethylene by measuring the resistance of the sample in the presence of ethylene gas. What about the selectivity of the device? Could it be used the sensor in a mixture of species as well?
Although it is true that EDS allows detecting the present of elements, using this method to measure the amount of Ag on the surface of ZnO is not precise. X-ray Photoelectron Spectroscopy is much more appropriate for nanomaterials and should be used instead if possible.
Could the author comment on the Ag nanomaterial structure? The SEM images given in Figure 7 are rather low in terms of resolution. Is the Ag in the form of nanoclusters? Layers? Crystalline? The addition of TEM data would give additional value to the paper.
Could the author comment on the stability and durability of the sensing device?
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Dear Editor
After careful reading of the revised paper, I consider that all suggestions for changes were considered and the questions answered.
Therefore, I consider that the paper can be accepted in the present form.
cordially
Reviewer 1
Reviewer 2 Report
This paper can be published.
