Modern views on the mechanism of oxygen reduction reaction on metal-free heteroatom-doped carbon nanostructures. Quantum chemical approach

This review summarizes the modern views on the mechanism, active site structure, and thermodynamics of the electrochemical oxygen reduction reaction catalyzed by heteroatom-doped carbon nanostructures for the subsequent rational design of catalytic sites and development of promising metal-free cathode materials for fuel cells for next-generation energy systems. The effect of both classic (B, N, S, P, O, Hal) and advanced "hybrid" (Si, Se) dopants in various states and in two- or threecomponent forms on the activity modulation of oxygen adsorption sites and on the reaction mechanism is considered. Particular attention is paid to the evolution of the views on the role of silicon, which switched from considering silicon to be inert due to its high oxophilicity to the discovery of unique catalytic properties of silicon in SiNx type catalytic sites. The conclusions made in the review open up new opportunities for the targeted design of hierarchical materials with adjustable properties via precise control of the composition and structure of heteroatom defects. The bibliography includes 252 references.