Triple-reaction-center catalysis drives simultaneous oxidation-reduction towards diverse emerging contaminants under oxidant-free conditions.

Abstract

Precisely designed self-driven single-atom catalysts (SACs) can achieve efficient degradation of emerging contaminants (ECs) without oxidants addition, but such systems often exhibited selectivity limited to electron-donating ECs, lacking broad-spectrum degradation capability. To address this limitation, a triple-reaction-center catalyst (Co⁰/CoN₂-SAC) is designed in this study, integrating an electron-deficient region based on carbon framework and an electron-enriched region featuring both metallic cobalt (Co⁰) and atomically dispersed CoN₂ sites. The electron-deficient region facilitates ECs adsorption through π-π interactions, and the CoN₂ sites in the electron-enriched region serve as electron acceptors, extracting electrons from electron-donating ECs. While the Co⁰ sites in the electron-deficient region serve as the electron donor for donating the electron towards electron-withdrawing ECs accompanying with reactive atomic hydrogen (H*) and •OH attacking, enabling efficient reductive degradation of electron-withdrawing ECs. As a result, the Co⁰/CoN₂-SAC system exhibits broad-spectrum degradation capability for both electron-donating and electron-withdrawing ECs, whereas the acid-leached counterpart lacking Co⁰ shows activity solely toward electron-donating species. Elucidation of this simultaneous oxidation-reduction mechanism provides critical insights for the rational design of adaptive catalytic systems capable of treating complex wastewater matrices, ensuring robust contaminant removal across diverse industrial and municipal water treatment applications.