Excellent Performance and Feasible Mechanism of ErOx-Boosted MnOx-Modified Biochars Derived from Sewage Sludge and Rice Straw for Formaldehyde Elimination: In Situ DRIFTS and DFT
Round 1
Reviewer 1 Report
In this work, Wang and coworkers reported the synthesis of ErOx and MnOx composites supported by biochars derived from sewage sluge and rice straw, the mechanism and performance of HCHO elimination over them combining experimental and theoretical efforts. By carefully reading, I found the manuscript not well written and the following should be addressed before the manuscript can be considered further.
l The language of the manuscript should be polished. For example, several terms were used to express the “formaldehyde elimination”, these should be unified throughout the manuscript. Furthermore, there are many grammar mistakes, typos and format mistakes, these should be corrected before resubmission.
l There are many recent publications concerning HCHO elimination, relevant results should be cited and compared together when convenient, such as DOI: 10.1039/c7cy00307b, 10.1039/d1cp00814e, especially when discuss about the reaction mechanism and performance.
l DOM, VOC were not defined in the manuscript but used several times. BAC was used before definition in the abstract. The term “carrier” should be replaced with “support”.
l Lines 39-41 should be reformatted.
l On lines starting 60, the authors mentioned “However, the applications of these common metal oxide carriers were limited by certain 60 disadvantages, such as irregular shapes, unsuitable sizes, uneven structures, and high 61 prices [12, 13]…….”. This should be revised to avoid misleading. Biochar was not born as a replacement of common oxides as catalyst support. It also has its own problems.
l Table 1 and Figure 2 should be reorganized.
l On lines starting from 196, the authors mentioned “Combined with sub-196 sequent SEM analysis and experimental results, the specific surface area was not the ex-197 clusive determinant of the activity of samples.” But the experimental results were not mentioned yet.
l There are several peaks at small angles on XRD of primordial BAC, but was not assigned and disappear after modification in Figure 5. Please address in the context.
l The authors mentioned “the peaks with lower binding energy values at 528.2eV-528.7eV corresponded to 325 lattice oxygen (Oα),” What is the lattice containing this lattice oxygen?
l It’s claimed “Throughout 409 the entire heating process, 15%Er0.5Mn0.5/BAC exhibited better EHCHO than 410 15%Er0.5Mn0.5/SAC and 15%Er0.5Mn0.5/SAW, which could be ascribed to possibly the fact 411 that 15%Er0.5Mn0.5/BAC was the neutralization of 15%Er0.5Mn0.5/SAW and 412 15%Er0.5Mn0.5/SAC theoretically”. What is this EHCHO ?
l On lines starting 569, the authors mentioned “Meanwhile, the Krevelen (MVK) mechanism expounded by Mars-Van could confirm the 569 catalytic oxidation of HCHO by supported metal oxide catalysts on carbon materials [60].” This should be rewrite to avoid misleading.
l Figures 14 and 15 is too small to read. As Figure 14 is a proposed mechanism, it should be a scheme rather than a Figure.
l Caption of Section 4.2 is confusing and should be revised.
l According to Figure 16, the adsorption energy of HCHO is ~-2 eV, this implies HCHO adsorption is too strong. Why?.
There are many grammar mistakes, typos and confusing terms.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors represent DRIFTS and DFT approaches to investigate the reactivity of ErOx boosted MnOx v/s MnOx biochars derived from sewage sludge and rice straw for formaldehyde elimination. The insights derived from this study could have a significant impact on the development of the next generation of catalyst for HCHO removal. The authors have mostly offered a rigorous characteristic analysis to support their claims and further confirmed with DFT optimized structures. I would recommend publication after minor revision. See comments below.
1. Figure 16 energy profile is confusing. For Figure 16, please add the same Figure label shown in Figure 15. It seems that the rate determining step (RDS) of MnO2 structure should be CH2O2* to CO2* rather than HCOO* to CO2* and for Er-MnO2 should be HCOO* to CO2* rather than CO2* to CO2.
2. Figures 14 and 15 are not fully clear. Increase the font size of Figure 14. In Figure 15, for better visualization keep only those atoms which are involved in the reaction profile rather whole support system. One full model system can be added in SI as a representative example.
3. In line 623: change formul to formula.
4. In line 636: add “rate” before determination step.
Comments for author File: Comments.pdf
NA
Author Response
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Author Response File: Author Response.pdf
