Singlet oxygen-mediated water purification by Cu⁰ anchored amorphous FeOOH via oxygen activation

Abstract

Reactive oxygen species (ROS) play a critical role in pollutant degradation. However, achieving efficient and sustainable catalytic systems for ROS generation remains a considerable challenge. In this study, we designed a crystalline-amorphous hybrid material (a-FeOOH-Cu⁰) for water decontamination via molecular oxygen activation. Characterization results indicated that a-FeOOH-Cu⁰ contained abundant low-valent copper species and exhibited electronic redistribution. These properties facilitated the direct cleavage of O−O bonds while bypassing the formation of *OOH intermediates, ultimately leading to a 1.44-fold and 2.91-fold increase in the concentrations of •OH and ¹O₂, respectively, compared to bulk Cu⁰. The abundant ROS significantly enhanced the removal of various organic contaminants (i.e., oxytetracycline, rhodamine B, bisphenol A). Further investigations identified ¹O₂ as the dominant ROS responsible for oxytetracycline degradation, with low-valent copper species serving as crucial active sites. Moreover, the a-FeOOH-Cu⁰ composite demonstrated high stability, good reusability, and strong resistance to matrix interference. This study highlights the potential of crystalline-amorphous hybrid materials in enhancing ROS production and provides a promising strategy for aquatic environmental remediation.

Graphical abstract

Keywords

Reactive oxygen species / Crystalline–amorphous hybrid / Molecular oxygen / Copper species / Singlet oxygen

Highlight

	● An amorphous-crystalline hybrid with abundant low-valent Cu was synthesized.
	● FeOOH-Cu0 was used to activate molecular oxygen for sustainable water remediation.
	● FeOOH-Cu0 enhanced 1O2, •O2− and •OH generation compared to bulk Cu0, respectively.
	● 1O2 played crucial role for OTC removal in a-FeOOH-Cu0/air system.

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