Atomically Dispersed p‐Block Aluminum‐Based Catalysts for Oxygen Reduction Reaction

Abstract

The main group metals are commonly perceived as catalytically inert in the context of oxygen reduction reactions (ORR) due to the delocalized valence orbitals. Regulating the local environment and structure of metal center coordinated by nitrogen ligands (M‐Nx) is a promising approach to accelerate catalytic dynamics. Herein, we, for the first time, report the atomically dispersed Al catalysts coordinated with N and C atoms for 4‐electron ORR. The axial coordinated pyrrolyl N group (No) is constructed in the Al‐N4‐No moiety to regulate the p‐band structure of Al center, effectively steering the local environment and structure of the square planar Al‐N4 sites, which typically exhibit too strong interaction with ORR intermediates. The dynamic covalency competition of axial Al‐No and Al‐O bonding could endow the Al center with moderate hybridization between Al 3p orbital and O 2p orbital, alleviating the binding energy of ORR intermediates. The as‐prepared Al‐N4‐No electrocatalyst exhibits excellent ORR activity, selectivity, and durability, along with the rapid kinetics as demonstrated by in situ Raman spectroscopy. This work offers a fundamental comprehension of the fine regulation on p‐band and guides the rational design of main‐group metal‐based single atom catalysts.

Activity Origin and Catalytic Mechanism of the M–N–C Catalysts for the Oxygen Reduction Reaction

“…(g) Schematic synthesis of Al–N–C-950 catalysts and (h) LSV curves of Al–N–C-950 and reference catalysts. Reprinted with permission from ref . Copyright 2024, Wiley-VCH.…”

“…(h) Full in situ Raman spectrum of Al–N–C-950. Reprinted with permission from ref . Copyright 2024, Wiley-VCH.…”

“…In addition, Lyu et al synthesized Fe–N–C catalysts containing pyridinic N vacancies (FeNC-V N ) and employed in situ Raman spectroscopy to reveal the dynamic evolution of *O 2 – (∼1110 cm –1 ) and *OOH (∼1490 cm –1 ) in the aqueous ZAB, demonstrating the dominance of the 4e – association mechanism (Figure g). Chen et al also monitored the dynamic evolution of *O 2 – and *OOH on Al–N–C catalysts (Figure h). Notably, they proposed that the Raman peak heights can represent the reduction current, while the Raman peak height’s sensitivity offers insights into rate-determining steps.…”

“…2 of 0.802 and 0.875 V (Figure7e and f). What's particularly interesting is that Zhao et al201 reported a p-block metal-based atomically dispersed Al−N−C catalyst with axial pyridine N coordination for 4e − ORR (Figure 7g and h). The pyridine N (N o ) was constructed in the Al−N 4 -N o moiety to regulate the p-band structure of the Al center, effectively reducing the adsorption energy of the ORR intermediates on the Al−N 4 site.…”