Investigation of the photocatalytic activity of Ho/Co co-doped CuAl₂O₄ and CNTs-based composite for effective removal of crystal violet and brexin

The current work presents the fabrication of CuAl 2 O 4 (CA1), Ho/Co co-doped CuAl 2 O 4 (CA2), and Ho/Co co-doped CuAl 2 O 4 @CNTs (CA3) by the co-precipitation process for enhanced photocatalytic activity. Several characterization techniques revealed the phase structure, morphology, optical behavior, and bonding properties of the prepared materials. Optical analysis confirmed the narrowing of the band gap and the modification of the electronic structure from CA1 to CA3, indicating an improved absorption of the visible light. The photocatalytic degradation efficacy of the fabricated materials was studied using brexin (BRX) and crystal violet (CV) as model pollutants. The ternary composite degraded 81% BRX and 72% CV over a course of 70 mins under visible light illumination, accompanied by an improved degradation rate constant of 0.024 min -1 and 0.017 min -1 , respectively. The improved photocatalytic performance of the composite arises from the combined impact of Ho/Co co-doping and CNT incorporation. Ho and Co doping causes lattice distortion, which promotes the excitation of the charge carriers in the presence of visible light, while the CNTs network promotes rapid charge transfer and also suppresses the charge recombination, which is supported by PL quenching results. These findings suggest that CA3 could potentially be used as an effective photocatalyst for water remediation.