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Competitive adsorption on single-atom catalysts: Mechanistic insights into the aerobic oxidation of alcohols over CoNC

Huang, Kuntao, Fu, Hongquan, Shi, Wen, Wang, Hongjuan, Cao, Yonghai, Yang, Guangxing, Peng, Feng, Wang, Qiang, Liu, Zhigang, Zhang, Bingsen, Yu, Hao
Journal of catalysis 2019 v.377 pp. 283-292
adsorption, aqueous solutions, benzaldehyde, benzyl alcohol, catalysts, catalytic activity, electrochemistry, moieties, oxidation, oxygen, solvents
MeNC catalysts have received intensive scientific interest as non-noble-metal single-atom catalysts (SAC) for electrochemical- and thermocatalytic reactions. However, the lack of understanding of its properties hinders further improvement of the catalytic performance. An interesting issue is the molecular details of the reaction involving more than one reactant, since the activation of the second reactant is inevitably affected by the first one on SAC. Here, we synthesized CoNC SACs for the aerobic oxidation of benzyl alcohol (BA) to benzaldehyde. The catalyst exhibited excellent activity for this reaction, among the most active non-noble-metal catalysts. Differently from particulate metal or metal oxide catalysts, the CoNC SAC displayed “self-poisoning” due to the strong competitive adsorption of BA to O2, as revealed by kinetics experiments and density functional theory calculations. Moreover, we rationalized the poisoning effect of polar moieties, including organic solvents and aqueous solutions, on the SAC. These results shed light on the catalytic behavior of aerobic oxidation of BA on the molecular level and enable the rational design of catalytic organic synthesis over CoNC SACs.