g-C₃N₄-mediated hierarchical Cu₂O composites: Understanding the evolution of porous hexapod morphology and evaluation of photocatalytic performance

In the present report, composites of cuprous oxide (Cu₂O) were successfully synthesized in the presence of 2D-graphitic carbon nitride (g-C₃N₄) in-situ to facilitate formation of intimate p–n heterojunctions akin to BHJ matrices. A series of composites were synthesized systematically varying several key reaction parameters. Evaluation employing detailed pXRD and FESEM provided critical insights of evolution and formation of these composites. Hierarchical architectures with exotic porous hexapod morphologies were of particular interest. Unequivocal evidences of uniform g-C₃N₄ distribution within the Cu₂O matrix captured employing FESEM, HRTEM, and HAADF implies entrapment during the nucleation and growth process. XPS analysis indicates an interaction between π-electrons of g-C₃N₄ nanosheets and Cu⁺ atoms as the driving force for secondary assemblies. UV–DRS, PL, time-resolved fluorescence, and EIS studies reveal the favorable opto-electronic properties suitable for photoexcitation, and effective charge-pair separation under visible light irradiation. Feasibility studies for photocatalytic performance were showcased employing a model dye Rhodamine-B. The appreciably faster kinetics of dye degradation exhibited by CuCN-20 (k = 9.09 × 10^–3 s⁻¹) with almost 83% degradation when compared to pristine Cu₂O (0.91 × 10^–3 s⁻¹) and pure g-C₃N₄ (1.7 × 10^–3 s⁻¹) as control showcased the potential. LC–MS analysis demonstrates the similarity of the N-de-ethylation-mediated dye degradation pathway.