Atomic‐Level Modulation of Electronic Density at Cobalt Single‐Atom Sites Derived from Metal–Organic Frameworks: Enhanced Oxygen Reduction Performance

Abstract

Demonstrated here is the correlation between atomic configuration induced electronic density of single‐atom Co active sites and oxygen reduction reaction (ORR) performance by combining density‐functional theory (DFT) calculations and electrochemical analysis. Guided by DFT calculations, a MOF‐derived Co single‐atom catalyst with the optimal Co1‐N3PS active moiety incorporated in a hollow carbon polyhedron (Co1‐N3PS/HC) was designed and synthesized. Co1‐N3PS/HC exhibits outstanding alkaline ORR activity with a half‐wave potential of 0.920 V and superior ORR kinetics with record‐level kinetic current density and an ultralow Tafel slope of 31 mV dec−1, exceeding that of Pt/C and almost all non‐precious ORR electrocatalysts. In acidic media the ORR kinetics of Co1‐N3PS/HC still surpasses that of Pt/C. This work offers atomic‐level insight into the relationship between electronic density of the active site and catalytic properties, promoting rational design of efficient catalysts.

Atomically Dispersed Mo Sites Anchored on Multichannel Carbon Nanofibers toward Superior Electrocatalytic Hydrogen Evolution

“…Manipulation strategies of electronic regulation and architectural engineering are commonly adopted to further optimize the catalytic behavior of the M–N–C SACs . Electronically, the coordination chemistry of the metal centers can be precisely modulated via incorporating multiple heteroatoms, regulating the coordination number, adjusting the oxidation state, and engineering the binding mode, which, in turn, enable improvement of the intrinsic activity and stability. − Because of the higher binding energies of N and O related to C, the coordination of metal sites with N and O has been experimentally and theoretically demonstrated to not only profitably optimize the chemisorption behavior of the intermediates in the catalytic process but also firmly anchor the isolated single metal atoms via the formation of chemical bonds caused by the altered electron distribution on the defective sites. − On the other hand, architecturally, the optimization of the geometric configuration and the textural porosity of the SAC supports allow the improvement of the accessibility of active sites, promote mass diffusion, and enhance the electron-transfer efficiency, significantly expediting the electrocatalytic reaction kinetics. − In this regard, introducing abundant open mesoporous channels within substrate can further significantly boost the electrocatalytic performance . Among diverse carbonaceous supports for immobilizing SACs, carbon nanofibers (CNFs) have recently aroused considerable research interest due to their high aspect ratio, excellent mechanical strength, interconnected fibrous networks for mass transportation, and continuous efficient highways for electron transfer. − Nonetheless, it has hitherto been quite challenging to build interconnected mesoporous nanochannels within CNFs via a straightforward, universal, and scalable synthetic methodology.…”

Single Mn Atom Anchored on Nitrogen‐Doped Graphene as a Highly Efficient Electrocatalyst for Oxygen Reduction Reaction

“…For example, CrN 4 ‐G, OsN 4 ‐G, and MoN 4 ‐G exhibited poor ORR activities because the strong adsorption for OH hindered the hydrogenation reaction of OH to H 2 O [8d,9–10] . Benefitting from the suitable interactions between Fe and Co with ORR intermediates, FeN 4 ‐G and CoN 4 ‐G were demonstrated to achieve superior or comparable catalytic performances to commercial Pt/C [3a,7c,8a,11] . However, due to the effect of the Fenton reaction, [12] FeN 4 ‐G still suffer from insufficient durability, limiting the practical applications in fuel cells and metal‐air batteries.…”

CoSe2 supported single Pt site catalysts for hydrogen peroxide generation via two‐electron oxygen reduction

“…To further explore why the Co sites around Pt on Pt 1 /CoSe 2 (1 1 0) have efficient H 2 O 2 generation performance, the projected DOS (PDOS) analysis was performed. [52][53][54] As shown in Figure 5, the PDOS of O-p orbital (from the terminal oxygen in *OOH) and Pt-d orbital or Co-d orbital (from the surface metal sites) for different samples are presented. The hybridization degree between the active metal site and oxygenated intermediates is a crucial activity descriptor, [55][56][57] 5D,E).…”