Synergistic mechanism of facet junction and p-n junction optimizing charge transfer for enhanced photocatalytic hydrogen production in the CuCo2O4/Cd0.5Zn0.5S system

• Published in: Applied surface science 2025-03, Vol.685, Article 162043
• Main Authors: Dong, Mei, Li, Wenjun, Geng, Liang, Huang, Ruixue, Liu, Yuan, Han, Hongli
• Format: Article
• Language: English
• Subjects: CuCo2O4; Facet junction; Morphology; P-n junction; Photocatalytic
• ISSN: 0169-4332
• DOI: 10.1016/j.apsusc.2024.162043

[Display omitted] •CuCo2O4 hollow porous nanospheres, nanosheets, and nanowires were synthesized.•CuCo2O4/Cd0.5Zn0.5S composites exhibit high hydrogen production rates.•(311)/(111) facet junction significantly facilitates charge transfer and separation.•Charge transfer occurs via potential differences, band bending, and electric fields.•Synergistic effect of facet junction/p-n junction achieves efficient H2 production. Herein, CuCo2O4 hollow porous nanospheres (HPN), nanosheets (NS), and nanowires (NW) were synthesized via solvothermal and calcination processes, and were used to construct efficient heterojunctions with Cd0.5Zn0.5S. Interestingly, the unique hollow porous structure exhibits enhanced light absorption, large pore diameter (12.57 nm), and strong hydrophilicity (10.05°). Photocatalytic results indicate that CuCo2O4 HPN/Cd0.5Zn0.5S achieves the optimal hydrogen production rate, which is 5.4, 1.2, and 1.3 times than that of pure Cd0.5Zn0.5S, CuCo2O4 NW/Cd0.5Zn0.5S and CuCo2O4 NS/Cd0.5Zn0.5S, respectively. High-resolution TEM and theoretical calculations confirm that (311)/(111) facet junctions in CuCo2O4 nanospheres form a work function difference (0.24 eV), which significantly facilitates charge transfer and separation. Mott-Schottky and Ultraviolet photoelectron spectroscopy analyses indicate that p-type CuCo2O4 and n-type Cd0.5Zn0.5S have staggered energy levels and a distinct Fermi level difference (1.85 eV), which leads to rearrangement of the Fermi energy level and modulation of charge transfer pathway. The resulting energy band bending and built-in electric field promote charge transfer at the heterojunction interface more effectively. The synergistic mechanism of the facet junction and p-n junction finally achieves high-efficiency hydrogen production. This work provides new insights into how to construct efficient p-n heterojunction photocatalysts and presents the synergistic mechanism of facet junction and p-n junction.