Atomically dispersed copper catalysts with dual reaction sites and high mass transfer efficiency for highly-efficient Fenton-like degradation

Abstract

Atomically dispersed metal catalysts (ADMCs) with dual reaction sites have been extensively utilized in permonosulfate (PMS)-based Fenton-like systems for the degradation of antibiotic wastewater, yet challenges remain in synthesizing cost-effective and highly active Cu-based catalysts. Herein, atomically dispersed Cu catalysts supported on N-doped cellulose-derived carbon (Cu₁/NC-700) are synthesized via a sol-gel combined with high-temperature pyrolysis method. The formed Cu−N_x and pyrrolic N dual reaction sites enhance the activation of PMS and adsorption of oxytetracycline (OTC), thereby shortening the migration distance of radicals towards the OTC. Moreover, graphitic N accelerates electron transfer to facilitate the Cu²⁺/Cu⁺ cycle for the generation of highly efficient active species, including •OH, ¹O₂, SO₄^•−, and O₂^•−. The Cu₁/NC-700 exhibits significant catalytic activity for the degradation of OTC, achieving 96.6% degradation efficiency within 60 min at an initial substrate concentration of 50 mg/L, a high turnover frequency (0.279/min) and apparent rate constant (0.0827/min), which markedly surpassed those of Cu₁/NC-600, Cu₁/NC-800, and Cu_NPs/NC. The results of chemical quenching experiments, electron paramagnetic resonance, and electrochemical analysis show that ¹O₂-dominated non-radical pathway is the main mechanism rather than the radical pathway in the Cu₁/NC-700+PMS+OTC system. This work presents a straightforward and cost-effective strategy for the synthesis of ADMCs for the treatment of tetracyclines wastewater.

Graphical abstract

Keywords

Atomically dispersed metal catalysts / Dual reactive sites / Sol-gel method / Cellulose-derived porous carbon / Mass transfer efficiency

Highlight

	● Successful synthesis of Cu1/NC-700 via sol-gel combined with pyrolysis method.
	● Graphitic N, Cu−N x and pyrrolic N species are the main reaction sites of Cu1/NC-700.
	● Porous NC improves the mass transfer efficiency to enhance reaction rate.
	● Graphitic N accelerates electron transfer to facilitate the Cu2+/Cu+ cycle.
	● 1O2-dominated non-radical oxidation predominates over radical pathways.

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