Modulating π − <i>d</i> Conjugated Coordination in Bionic Cu/Cu₂O Heterojunctions for Efficient Photodegradation of Organic Contaminants

Abstract In situ grown copper (Cu) metal is commonly integrated with Cu 2 O to enhance charge separation and improve photocatalytic degradation of azo dyes, such as Orange II and Methyl orange (MO). However, limited solvent diffusion remains a critical challenge for effective pollutant removal. Inspired by the dandelion structure, this work synthesizes a Cu/Cu 2 O composite with an interconnected nanotube structure and hollow nanosphere, facilitating solvent transport and increasing active surface area. The optimized Cu/Cu 2 O‐S3 catalyst achieves 93 % photodegradation efficiency of Orange II and maintains 98 % stability over five cycles at a concentration of 100 mgL −1 , significantly outperforming MO. While previous studies have attributed this performance to the dihedral angle and planarity of Orange II, the role of photogenerated electron transport at the catalyst‐dye interface is largely overlooked. Here, this work reveals that electron transfer from the 3 d orbitals of Cu transfer to the 2 p energy levels of N, C, O atoms, enhancing carrier mobility and binding interactions. Moreover, the extra α‐OH group in Orange II promotes uniform electronic distribution and planar π‐bond formation, further improving photocatalytic performance. These insights provide a deeper understanding of photocatalytic mechanisms and offer valuable strategies for designing more efficient catalysts.