Insights into the in-situ generation of singlet oxygen via molecular oxygen activation over NiO@CuxO NRs/CF nanocomposite catalysts: Mechanisms of singlet oxygen evolution and chloroquine phosphate degradation

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Herein, we fabricated a novel NiO@CuxO nanorods (NRs) composite electrode grown in-situ on copper foam (CF), designated as NiO@CuxO NRs/CF. This electrode demonstrates excellent performance in a heterogeneous electro-Fenton-like system. It efficiently activates O2 to generate 1O2 in-situ without the addition of oxidant precursors and effectively degrades chloroquine phosphate (CQ). The combination of NiO and CuxO nanoarrays created multiple synergistic sites for molecular oxygen adsorption and activation. The addition of NiO induced the formation of low-valence Cu species and effectively optimized oxygen reduction reaction (ORR) kinetics. This enhancement led to an increased generation of key intermediates (·O2– and ·OH), which further promoted the efficient production of 1O2 through the chain reaction mediated by ·O2– and ·OH. NiO@CuxO NRs/CF achieved a 3.9-fold increase in 1O2 production compared to the CF electrode. NiO@CuxO NRs/CF electrodes exhibited exceptional performance in degrading CQ across a wide pH range (3-11). Meanwhile, it also displayed remarkable stability and anti-interference capability, highlighting their promising potential for practical applications. The study provides an innovative strategy for the in-situ production of 1O2 through molecular oxygen activation with a bimetallic composite catalyst to efficiently degrade organic pollutants.