Modulating Electronic Structure of Atomically Dispersed Nickel Sites through Boron and Nitrogen Dual Coordination Boosts Oxygen Reduction

Abstract

Atomically dispersed 3D transitional metal active sites with nitrogen coordination anchored on carbon support have emerged as a kind of promising electrocatalyst toward oxygen reduction reaction (ORR) in the field of fuel cells and metal-air cells. However, it is still a challenge to accurately modulate the coordination structure of single-atom metal sites, especially first-shell coordination, as well as identify the relationship between the geometric/electronic structure and ORR performance. Herein, a carbon-supported singleatom nickel catalyst is fabricated with boron and nitrogen dual coordination (denoted as Ni-B/N-C). The hard X-ray absorption spectrum result reveals that atomically dispersed Ni active sites are coordinated with one B atom and three N atoms in the first shell (denoted as Ni-B 1 N 3 ). The Ni-B/N-C catalyst exhibits a half-wave potential (E 1/2 ) of 0.87 V versus RHE, along with a distinguished long-term durability in alkaline media, which is superior to commercial Pt/C. Density functional theory calculations indicate that the Ni-B 1 N 3 active sites are more favorable for the adsorption of ORR intermediates relative to Ni-N 4 , leading to the reduction of thermodynamic barrier and the acceleration of reaction kinetics, which accounts for the increased intrinsic activity.

Crafting core–shell heterostructures of carbon nanotubes and N,O-coordinated cobalt site-impregnated conjugated porous polymers for highly efficient oxygen reduction

“…3i and Table S2†). 39–49 Meanwhile, the CNTs/Co–N,O-CP-based zinc–air battery exhibits only a negligible voltage drop after 130 h of continuous discharging (at 10 mA cm −2 ) (Fig. S34†), signifying superior stability.…”

Recent progress in heteroatom doping to modulate the coordination environment of M–N–C catalysts for the oxygen reduction reaction

“…The introduction of the B atom with low electronegativity of the Zn-N 4 site can retain the 4s electrons of the central Zn atom, which endows the adjusted Zn + (3d 10 4s 1 ) structure with enough delocalized electrons to optimize the adsorption/desorption energy of the oxygen intermediates, thus enhancing the charge transfer ability during the ORR reaction. 51 Similarly, Wang et al 52 successfully prepared a novel B-doped Ni-N-C catalyst by the chemical precipitation and pyrolysis process, named as Ni-B/N-C. AC HAADF-STEM, XANES, and the corresponding FT EXAFS spectrum analysis of the Ni-B/N-C catalyst demonstrated that the single Ni atom was coordinated by three N atoms and one B atom (Ni-B 1 N 3 ). For ORR, the optimized Ni-B/N-C catalyst showed the highest E 1/2 (0.87 V vs. RHE) and J k @0.9 V (2.53 mA cm À2 ), which far exceeded that of the Ni-N-C, B/N-C, and N-C catalysts.…”

Single-Atom-Based Oxygen Reduction Reaction Catalysts for Proton Exchange Membrane Fuel Cells: Progress and Perspective

“…Theoretical calculations unveiled that the structural change is due to carbon atoms in the N-doping C layer deposited into the vacant-rich site in S1 and then forming a more graphitized and stable S2 site (Figure f). In addition, modifying the local coordination environment by decorating other heteroatoms with different electronegativities (e.g., Se, S, or B) into the carbon skeleton has also shown great potential for enhancing ORR activity and stability. For example, Wang et al reported a B doping of the Ni–N–C catalyst (denoted as Ni–B/N–C), which was prepared by the chemical precipitation of the Ni-doped ZIF-8 precursor and B source and subsequent pyrolysis.…”