NOx Abatement by a TiO2-Based Coating under Real-Life Conditions and Laboratory-Scale Durability Assessment
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe purpose of this study was to present a new field experiment on the application of a photocatalytic coating to out door walls. Air quality monitoring stations were used to evaluate the NOx concentration reduction. The manuscript contains a lot of useful information. The study contributes to the reduction of nitric oxide. It is suitable for publication but some extra information, additional literature could increase the level of manuscript.
1. From a historical point of view it would be advisable to involve other rutile type, reducible type oxides which are active in NO reduction. Chromium oxide, nickel oxide ( Otto, K, and Shelef, M., Journal of Catalysis. 12, 361 (1968)) and SnO2 and SnO2 doped with chromium oxide (Journal of Catalysis 41 (1976) 202-211.; and Journal of Catalysis 54 (1978) 42-51.) were found to be excellent catalysts in the past.
2. I suggest referring to a review which deals with the investigation of TiO2 which is well-studied in many photochemical processes (Surface Science Reports, 6-7, (2011) 185-297).
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for AuthorsThis is a well written paper. The authors reported a new field test to evaluate the performance of a photocatalytic coating to reduce NOx concentration under real conditions, and to assess the durability of this process in a laboratory-scale test. Their results showed that canyon street whose walls were coated with TiO2 containing catalyst had lower NO and NO2 concentrations compared to the control canyon street (without catalyst coating walls), this effect being more pronounced in the vicinity of the pollution source. Laboratory test showed that the catalyst coating had good mechanical durability. Since majority research related to this topic focused on laboratory results, the field test results reported in this paper provided practical information under real conditions. From my opinion, this manuscript can be accepted for publication after address the following questions:
1. In Figure 3, labels of a), b), and c) are missing.
2. Lines 289-290 mentioned that “The local average wind speed in the canyon streets was less than 1 m/s: 0.75 m/s for the TC and 0.34 m/s for the UTC.”. But in Table 2, the wind speed is 8.0m/s for both TC and UTC. Please clarify.
3. Line 450, “this effect being more pronounced in the vicinity of the pollution source”. please explain why.
4. Minor typo in line 316, add space between “UTC streets. ”and “Figure 5”.
Comments on the Quality of English LanguageEnglish language is fine.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
