# Defect‐Engineered MOF/COF S‐Scheme Heterojunction With Dual‐Channel Charge Transport for Ultraefficient Solar‐Powered Heavy Metal Remediation

## TL;DR

This paper introduces a new photocatalyst design using defect engineering to improve solar-powered removal of heavy metals from water.

## Contribution

A defect-engineered MOF/COF S-scheme heterojunction with dual-channel charge transport is proposed for ultraefficient photocatalytic heavy metal remediation.

## Key findings

- The catalyst achieves 8.8 and 17.1 times higher UO2²⁺ removal rates compared to the parent MOF and COF.
- Oxygen vacancies extend carrier lifetime to 278 ps, 2.5 times longer than the parent materials.
- The design introduces a dual-channel charge transport mechanism, enhancing catalytic performance.

## Abstract

Rapid recombination of photogenerated carriers severely limits the photocatalytic performance of conventional semiconductor photocatalysts, while conventional heterojunctions generally suffer from inefficient charge separation and sluggish interfacial kinetics due to poor lattice matching and unidirectional recombination. Herein, we break through these limitations by constructing an oxygen vacancies (OVs)‐mediated S‐scheme via covalent bridging between a metal–organic framework (MOF) and a covalent organic framework (COF), coupled with vacuum‐induced OVs engineering. This novel architecture not only preserves the strong redox potentials of the constituent materials but also introduces dual‐channel charge transport pathways significantly enhancing carrier separation. Femtosecond transient absorption spectroscopy (fs‐TAS) reveals that the OVs‐induced trap states extend the carrier lifetime to 278 ps—2.5 times longer than the parent materials. The optimized catalyst achieves exceptional removal efficiencies for multiple heavy metal ions (Cu⁺, ReO4
−, MoO4
2
−, MnO4
−, Cr2O7
2
−, and UO2
2⁺), with UO2
2⁺ removal rates 8.8 and 17.1 times higher than those of the pristine MOF and COF, respectively. This work presents a universal “defect‐mediated dual transport” strategy, offering new insights into solar‐driven environmental purification and energy conversion.

Covalent bond MOF/COF S‐scheme which generated via vacuum‐induced oxygen vacancies are report. OVs at the interface can trigger a dual‐channel charge transport mechanism, significantly enhancing catalytic performance. This work not only designs a high‐performance photocatalysts for environmental remediation, but also induces a new concept of “defect engineering for charge transport optimization”, providing a groundbreaking approach to controlling charge dynamics in next generation photocatalytic systems.