Elaborating Nitrogen and Oxygen Dopants Configurations within Graphene Electrocatalysts for Two-Electron Oxygen Reduction

Abstract

Nitrogen (N) and oxygen (O) doping for carbon-based electrocatalysts is one of the most effective methods for improving the oxygen reduction reaction (ORR). Despite its significance, fundamental studies remain needed to determine the effects of atomic configuration on the two-electron (2e − ) oxygen reduction. In this study, we investigate the coupling effects between pyrrolic N and the O functional groups, including ether (O−C−O) and carbonyl (CO), on 2e − ORR. The results suggest that the 2e − ORR performance depends on the CO/O−C−O ratio. Among several atomic configurations, the coupling of pyrrolic N with carbonyl O is the most favorable type for the 2e − reaction, with 98.3% H 2 O 2 selectivity at 0.0 V (vs the reversible hydrogen electrode) in the alkaline electrolyte. Additionally, this combination exhibits considerably stable performance during long-term (12 h) durability test, demonstrating approximately 100% current retention. The experimental results were further supported by theoretical calculation, exhibiting optimal adsorption free energy of OOH* for the couple of pyrrolic N and carbonyl O.

Advances in Porous Graphene and Scalable Wet-Spinning Fiber Assembly

“…The graphene or GO can be punched using thermal or chemically assisted steam etching. 9 In contrast to the pristine morphology, the porous morphology in the individual building block shows unique chemical activity, 46 mass transfer characteristics, 47 and mechanical flexibility. 48 HGO LC solution was prepared via oxidative etching with H 2 O 2 to introduce holes in graphene sheets (Figure 7c).…”

“…The graphene or GO can be punched using thermal or chemically assisted steam etching . In contrast to the pristine morphology, the porous morphology in the individual building block shows unique chemical activity, mass transfer characteristics, and mechanical flexibility . HGO LC solution was prepared via oxidative etching with H 2 O 2 to introduce holes in graphene sheets (Figure c). , After spinning the HGO solution in a CaCl 2 coagulation bath, a flexible hygroscopic aerogel fibers are fabricated on a large scale through a supercritical drying process (Figure d) .…”

Revealing the atomic-scale configuration modulation effect of boron dopant on carbon layers for H2O2production

“…7 For instance, pyrrolic N atoms with a higher electronegativity can activate the p-conjugated system in carbon materials, effectively facilitating the adsorption of the OOH* intermediate, thereby contributing to the remarkable H 2 O 2 production efficiency. 14 Additionally, graphitization degree also has a notable influence on 2e À ORR activity by affecting the relevant electron migration dynamics. 15 Inspired by these studies, the rational design of advanced carbon materials with decent pyrrolic N abundance and graphitization degrees is expected to offer new opportunities to achieve brilliant 2e À ORR performance.…”

“…The relatively higher pyrrolic N content in Ni@B,N-C-5 may serve as active sites to activate the p-conjugated system in the carbon matrix, effectively facilitating the adsorption of the OOH*. 7,14 To verify this hypothesis, O 2 temperature-programmed desorption (O 2 -TPD) experiments were conducted. As shown in Fig.…”

Inhibited Surface Diffusion of High-Entropy Nano-Alloys for the Preparation of 3D Nanoporous Graphene with High Amounts of Single Atom Dopants

“…To explore competitive alternatives of precious metals or greatly reduce their loading amounts as highly active oxygen reduction reaction (ORR) or oxygen evolution reaction (OER) electrocatalysts, chemically/physically doped graphene has been receiving much attention because of their high electric conductivity, large specific surface area, high chemical stability, and tunable catalytic activity. − Particularly, nitrogen-doped graphene (NG) has been demonstrated as a high-efficiency ORR catalyst thanks to the N mediated C–O interaction. − However, most NGs have a low concentration of N dopant (∼3 at. %).…”