Cu-optimized long-range interaction between Co nanoparticles and Co single atoms: Improved Fenton-like reaction activity

The synergism between atomic clusters (ACs)/nanoparticles (NPs) and single atoms has recently become a research focus. However, previous works often focus on the simple interaction between pure NPs and SAs (partial view), instead of attention on how can we modify NPs or ACs to strengthen the intrinsic activity of whole metal NPs/ACs@M-N-C entity (integral perspective). Therefore, the strategies over the precise construction and performance optimization of entire metal NPs/ACs@M-N-C entity remained to be investigated.

In this study, Co-Cu alloy NPs@Co-N-C (CC@CNC) was constructed using Co/Cu-modified zeolitic imidazolate framework-8 (ZIF-8) as precursor, followed by the pyrolysis and acid etching. The incorporation of Cu induced formation of Co-Cu alloy NPs, originating from the low Tammann temperature of Cu, which was verified by the negative cohesive energy of Co₁₀Cu₃ (−0.06454, intending to aggregation) compared to that of Co₁₃ (+1.690995, intending to dispersion). The Co-Cu alloy NPs-supported Co SAs showed superior PMS activation efficiency compared to Co NPs-supported Co SAs (Co NPs@Co-N-C, C@CNC), evidenced by the decreased energy barriers of PMS adsorption (increased Co–O bond length)/PMS oxidation (increased O-H bond length and decreased O-O bond length) and SO₅^·- desorption (increased Co-O bond length), through optimizing dz²-O (PMS) and dxz-O (SO₅^·-) interaction. Therefore, the CC@CNC highly efficiently removed 80.67% of 20 mg/L carbamazepine (CBZ) within 5 min, which was superior to the C@CNC counterpart (58.99% within 5 min). The serial quasi in situ techniques indicated the occurred PMS oxidation reaction on Co SAs, which can selectively generate ¹O₂ to effectively eliminate CBZ. This study can lay solid foundation for the performance optimization strategy and underlying mechanism revelation in metal multiple-atom assembly@metal SAs catalysts at atomic orbital level.

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