# Unraveling Alkali Ion Electron Donation for Enhancing Heterogeneous Catalytic Oxidation

## TL;DR

This paper reveals how potassium ions can act as electron donors in catalysis by forming chains in WO3 tunnels, boosting reactions like soot oxidation.

## Contribution

A novel electron donation mechanism for potassium ions in heterogeneous catalysis is identified through confined chain structures in WO3.

## Key findings

- High-electron-density Kδ+ ions facilitate oxygen vacancy formation and lattice oxygen activation.
- Kδ+ ion-based catalysts achieve a 3.1-fold higher soot oxidation rate compared to conventional K⁺-ion catalysts.

## Abstract

Alkali ions, widely employed as promoters, play crucial roles in heterogeneous catalysis. However, their electron donation mechanism remains poorly understood because alkali ions do not have transferable electrons as metallic alkalis do. Here, a new mechanistic pathway is identified for potassium (K) ions to act as electron donors by constructing single chains of K ions confined within hexagonal WO3 tunnels with theoretical limit‐breakthrough K concentrations. The as‐produced high‐electron‐density Kδ+ (0<δ<1) ions not only facilitate the formation of oxygen vacancies that behave classical electronic effect but, more importantly, also directly donate electrons to [WO6] motif antibonding orbitals, thereby triggering the lattice oxygen activation. As a proof of concept, the resultant catalyst containing Kδ+ ions predominantly promotes soot oxidation with O2, a challenging solid‐solid‐gas reaction in automotive catalysis, achieving a reaction rate 3.1‐fold greater than the conventional K⁺‐ion confined counterpart. The electron donation effect of metalloid Kδ+ ions would be heuristic for enhancing other important heterogeneous catalytic reactions.

A new mechanistic pathway for potassium (K) ions as electron donors is identified by constructing single K ion chains confined within hexagonal WO3 tunnels. The as‐produced high‐electron‐density Kδ+ (0<δ<1) ions not only facilitate the formation of oxygen vacancies that behave classical electronic effect but, more importantly, also directly donate electrons to [WO6] motif antibonding orbitals, thereby triggering the lattice oxygen activation.