# Regulating Spin Polarization through Topological Defects in Carbon‐Based Metal‐Free Catalyst for Enhanced Fenton‐Like Activity

## TL;DR

A new method using topological defects in carbon-based catalysts improves Fenton-like activity by regulating electron spin.

## Contribution

A topological defect engineering strategy is introduced to regulate spin polarization in carbon-based metal-free catalysts.

## Key findings

- Pentagon defects on carbon nanotubes induce spin polarization and enhance electron transfer in Fenton-like reactions.
- The spin-polarized catalyst (E-C5) shows 63 times higher activity for 4-chlorophenol degradation than the unpolarized catalyst (E-C6).
- Spin polarization lowers the energy barrier for singlet oxygen generation in the Fenton-like reaction.

## Abstract

Regulating spin polarization has been recognized as a promising strategy to improve the catalytic performance across various catalytic domains, since the reaction barriers can be directly influenced by the spin state. However, the existing approaches to modulating the spin polarization of active centers mainly focus on the metal‐based catalysts, and those for the earth‐abundant carbon‐based metal‐free catalysts (CMFCs) are rarely reported. Here, a topological defect engineering strategy is proposed to regulate the spin polarization by introducing pentagon defects on the edge of CMFCs. Theoretical and experimental results indicate that the incorporation of pentagon defects on the edge induces a spin polarization, and more spin‐down electrons locate below the Fermi level, which enhances the electron transfer between peroxymonosulfate (PMS) and the catalyst, and reduces the energy barrier of the key *OOH intermediate during the generation of singlet oxygen (1O2). As a result, the derived spin‐polarized catalyst (E‐C5) shows remarkable Fenton‐like activity for 4‐chlorophenol (4‐CP) degradation, which is 63 times higher than that of the pristine unpolarized catalyst (E‐C6). This topological defect engineering represents an innovative and effective strategy to regulate spin polarization in carbocatalysts, and provides insightful inspirations for various catalytic fields.

A topological defect engineering strategy is proposed to regulate the spin polarization by introducing pentagon defects on the edge of carbon nanotubes. Theoretical and experimental results indicate that the incorporation of pentagon defects on the edge induces a spin polarization, and more spin‐down electrons locate below the Fermi level, which enhances the generation of singlet oxygen in Fenton‐like reaction.