Peer review of: Transition metal-like carbocatalyst (2020)

Reviewers' comments: 

Reviewer #1 (Remarks to the Author): 


The work presented in this manuscript discusses results on catalytic cleavage of strong bonds including 
hydrogen-hydrogen, carbon-oxygen, and carbon-hydrogen over nitrogen-doped graphenes. The main 
goal for these reactions is the selectivity, but except for the hydrogenation of 2, all others reactions 
provided either small selectivities (see C-O) or selectivity to less interesting products (N-O) or (C=C). 
Then, the manuscript provides justifications only for the activation of hydrogen based on H2/D2 
exchange experiments. The authors assumed the priority of these experiments mentioning that such an 
exchange “has only been demonstrated by catalysts based on transition metals like Ni and Pt”. However, 
literature already reported such an exchange for graphene-based materials (G. Sastre, A. Forneli, V. 
Almasan, V.I Parvulescu, H. Garcia, Isotopic H/D Exchange on Graphenes. A Combined Experimental and 
Theoretical Study, Appl. Catal. A: General 547 (2017) 52-59. ). 
The investigated reactions also require an interaction of substrate with the catalysts that is not 
documented. Spectral evidences for such interactions are missing. Calculations’ suggesting that “the α-
carbon of styrene is selectively chemisorbed to the graphitic N, forming a surface-bound intermediate 
with a D transferred to the styrene β-carbon” is important to be experimentally proved. Also important, 
comparative TOFs should be calculated for the present nitrogen-doped graphene and reference metal 
catalysts. 
Based on these the reviewer considers the manuscript is not enough mature to be published in Nature 
Communications. 



Reviewer #2 (Remarks to the Author): 

This manuscript describes development of carbon-based catalyst for hydrogenolysis of C-O linkages in 
aromatic oxygenates using molecular hydrogen, catalytic dehydrogenation of ethylbenzene and 
tetrahydroquinoline, and the selective hydrogenation of unsaturated functional groups in aromatics, 
including −C=O, −C=C−, −C≡C−, and −NO2. The carbon-based catalysts were synthesized by condensing 
ethylenediamine (EDA) and carbon tetrachloride by a hard template route, followed by carbonization 
under flowing Ar at 600 to 900 °C and then etching to remove the silica template, giving the materials 
NAC-600-NAC-900. Clearly, utilization of metal-free catalyst for activation of hydrogen at relative mild 
conditions is very meaningful topic. The results are remarkable but not convincing. This work could be 
published on Nature Communications if the results can be further confirmed. In addition, there is lack of 
solid evidence to define the active site and the reaction mechanism is unclear. Here are some specific 
criticisms: 
(1) Fe, Cu and other metals pollution is very common in HF, it is necessary to do more research to see if 
the presence of trace amounts of Fe, Cu or some other metals would be the real active species. It needs 
more evidence and control experiments. This is very important to support the conclusion of the current 
work. 
(2) Some control experiments should be performed to exclude the possibility of 2-PrOH as hydrogen 
source. 
(3) The authors said that “the initial rates in PPE conversion positively correlate only with absolute 
graphitic N content of the corresponding NAC catalysts by a second-order polynomial.” However, using 
peak fitting to obtain graphitic N content is not convincing because of overlap of the peaks in N1s XPS 
spectra. 
(4) The mechanisms of dihydrogen dissociation, hydrogenation and dehydrogenation are not clear. 
(5) If possible, I know it is difficult, some in-situ characterizations have to be carried to determine the 
possible active site on the carbon catalyst. 
Overall, in view of the above criticisms I do not recommend this paper for publication in the current 
form. To be suitable for Nature Communications, major revisions are necessary. 




Reviewer #3 (Remarks to the Author): 

The present study demonstrates that graphitic mesoporous carbon-nitrid materials synthesized 
following literature recipe can efficiently catalyze hydrogenation, dehydrogenation and 
hydrodeoxygenation of selected compounds. The synthesis of the catalysts were carefully controlled 
and the intermediate states and compositions were accurately characterized. N-sites with different 
oxidation states were identified by XPS (pyridinic, pyrrolic, graphitic and N-O). It has been shown that 
the catalysts can sufficiently chemisorb H2. The selected catalyst (NAC-800) could hydrodeoxygenate the 
model PPE molecule and a considerably high selectivity toward the C-O attack instead of the aryl rings 
has been shown. This is a clear advantage over many typical TM catalysts. The scope of the 
hydrodeoxygenation includes C-O, carbonyl, olefinic, alkynyl and NO2 groups. The same catalyst showed 
remarkable activity in dehydrogenation and hydrogenation as well. Thorough kinetic analysis has been 
performed and the kinetic order of the reactant PPE, H2 and catalyst has been determined. The catalytic 
mechanism was addressed by the kinetics measurements complemented by periodic DFT calculations. 
The calculations revealed catalytically feasible route (low TS energetically neutral pathway) and 
excluded kinetically (high TS) or thermodynamically unfavorable (too stable chemisorption) routes. A 
remarkable accord in experiment and theory is the plausible explanation of the role of the graphitic N-
pairs in the H2 activation. In my opinion the study provides very new ideas for the metal-free H2 
activation field and also they have disclosed this new type of catalysis for the family of mesoporous 
carbon-nitrid materials. The study has addressed important catalysis issues (thorough characterizations, 
different kinetic measurements) and provided convincing mechanistic insights for the operation of the 
catalysts. I propose the publication of the study. However I have the following issues which need to be 
addressed: 
i) Regarding selectivities: it is shown that NAC-800 boosts orthogonal processes: hydrogenation and 
dehydrogenation. Hence it would be important/useful to define circumstances or conditions or 
parameters how to obtain one or the other process during operation. 
ii) regarding the calculations: the NEB profiles should be shown in the SI or at least some information 
about the imaginary frequencies describing the activation processes probed by the computations should 
be given.