Effect of Cu ₂ O on the photocatalytic efficiency of NiO/C/Cu _x O

This study aims to elucidate the regulatory role of cuprous oxide (Cu
2
O) in the photocatalytic degradation of Rhodamine B (RhB) by NiO/C/Cu
x
O composites, with a focus on innovative material design and mechanism clarification. Acid red 14 (AR14) was creatively employed as a carbon source to fabricate NiO/C/Cu
x
O composites via a co-deposition-adsorption method followed by N₂ calcination. The composites were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS), and the effects of copper salt dosage and calcination temperature on Cu
2
O content and photocatalytic activity were investigated through RhB degradation assays. The results demonstrate that the NiO/0.5C/0.5Cu
x
O composite synthesized at 600°C with 0.5 g Ni(OH)
2
, 30 mL 0.5 mmol·L
-1
AR14, and 0.5 g Cu(NO
3
)
2
·3H
2
O exhibits the highest Cu
2
O content, achieving 98% RhB degradation within 2 h. A key innovation lies in the clarification that Cu
2
O enhances the photocatalytic performance by reducing the composite’s band gap to 1.19 eV (boosting visible light absorption) and minimizing photogenerated electron-hole recombination (exhibiting the lowest PL intensity). Additionally, active species capture experiments confirm that superoxide radicals (•O
2
) and hydroxyl radicals (•OH) are the dominant reactive species, and the catalyst maintains high degradation efficiency after four reuse cycles, demonstrating excellent stability. This work provides a novel strategy for using AR14 as a carbon source in fabricating metal oxide composites and deepens the understanding of Cu
2
O’s modulation mechanism in photocatalysis, offering valuable insights for the design of high-efficiency carbon-based metal oxide photocatalysts for organic pollutant degradation.