Insights into the Mechanism of Ozone Activation and Singlet Oxygen Generation on N-Doped Defective Nanocarbons: A DFT and Machine Learning Study

Abstract

N-doped defective nanocarbon (N-DNC) catalysts have been widely studied due to their exceptional catalytic activity in many applications, but the O 3 activation mechanism in catalytic ozonation of N-DNCs has yet to be established. In this study, we systematically mapped out the detailed reaction pathways of O 3 activation on 10 potential active sites of 8 representative configurations of N-DNCs, including the pyridinic N, pyrrolic N, N on edge, and porphyrinic N, based on the results of density functional theory (DFT) calculations. The DFT results indicate that O 3 decomposes into an adsorbed atomic oxygen species (O ads ) and an 3 O 2 on the active sites. The atomic charge and spin population on the O ads species indicate that it may not only act as an initiator for generating reactive oxygen species (ROS) but also directly attack the organics on the pyrrolic N. On the N site and C site of the N 4 V 2 system (quadri-pyridinic N with two vacancies) and the pyridinic N site at edge, O 3 could be activated into 1 O 2 in addition to 3 O 2 . The N 4 V 2 system was predicted to have the best activity among the N-DNCs studied. Based on the DFT results, machine learning models were utilized to correlate the O 3 activation activity with the local and global properties of the catalyst surfaces. Among the models, XGBoost performed the best, with the condensed dual descriptor being the most important feature.

Amino Acid Transporter as a Potential Carrier Protein for the Root-to-Shoot Translocation of Polybrominated Diphenyl Ethers in Rice

“…Besides, atomic charges of the ether-bond oxygen ( Q O ), the carbons at sites 4 ( Q C4 ) and 4’ ( Q C4’ ) were found to be significant in determining the relationship with TF, with coefficients of 1.75, 1.47, and 1.42, respectively (Figure b). To understand their contribution to the PBDE-LHT interaction, we analyzed the results of molecular docking as previous studies have reported that the binding affinity between compounds and proteins depends substantially on atomic energy contributions. , A strong positive correlation ( r = 0.89, p < 0.05) was established between the energy contribution of the oxygen atom in PBDEs and the corresponding TF (Figure c). Specifically, the highest contribution (28.4%) was observed in BDE-77, which was followed by BDE-47 (20.7%), BDE-99 (19.5%), BDE-153 (14.2%), and BDE-209 (11.2%).…”

Oxygen Vacancies Enhanced Ozonation toward Phenol Derivatives Removal over Ov-Bi2O3

“…DFT calculation revealed that O 3 first decomposes into an *O ads (*O ads was generally an intermediate for generating other ROS and determined the production rate of ·OH) on Bi 2 O 3 and O v -Bi 2 O 3 surfaces and an O 2 species. However, the pathway for O 3 decomposition over Bi 2 O 3 needs to overcome an activation barrier of 0.91 eV, which is higher than that over O v -Bi 2 O 3 (0.39 eV). − Moreover, O 3 decomposition on O v -Bi 2 O 3 is significantly more exothermic than on Bi 2 O 3 , indicating that O v -Bi 2 O 3 is more effective at initially activating O 3 and for the catalytic ozonation. Hence, we reformulated the ozone reaction formula, and the formulas are as follows: …”

Single-Atom Fe-N4 Sites for Catalytic Ozonation to Selectively Induce a Nonradical Pathway toward Wastewater Purification

“…The relative energy changes are shown in Figure b, and the reaction processes were exothermic and spontaneous. Based on the Mulliken charges and spin population calculated by DFT (Figure c), *O ad with −0.51 charge and 0.59 spin population indicated the existence of an unpaired electron in *O ad , which could act as an effective ROS to attack the surface-adsorbed organics, such as OA . O 2 species-1 showed approximately zero charge and spin population, and was determined to be 1 O 2 ( 1 Δ g ).…”

“…In addition, *O ad was also a crucial intermediate in the catalytic ozonation process and might react with ozone molecule to generate O 2 •– . AIMD was used to simulate the reaction of *O ad and O 3 .…”