Fully-depleted dual P–N heterojunction with type-II band alignment and matched build-in electric field for high-efficient photocatalytic hydrogen production

• Published in: International journal of hydrogen energy 2021-10, Vol.46 (73), p.36069-36079
• Main Authors: Ding, Yaya, Zhang, Jingyu, Yang, Ying, Long, Lizhen, Yang, Li, Yan, Lijuan, Kong, Wenjie, Liu, Fuchi, Lv, Fengzhen, Liu, Jun
• Format: Article
• Language: English
• Subjects: Build-in electric field; Dual PN-heterojunction; Full-depleted; Photocatalytic hydrogen evolution; Type-II band alignment
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2021.08.175

In this work, a dual p-n heterojunction of Cu2O/Ni(OH)2/TiO2 with type-II band alignment and matched build-in electric field was fabricated. This dual p-n heterojunction promoted the separation and transfer of charge carriers, which is much more efficient than individual p-n heterojunction. Photocatalytic hydrogen evolution under the simulated sunlight shows a high rate of 6145 μmol g−1 h−1 for Cu2O/Ni(OH)2/TiO2, which is 1.9 and 2.7 times that of Ni(OH)2/TiO2 and Cu2O/TiO2, respectively. The apparent quantum yield of Cu2O/Ni(OH)2/TiO2 is about 20.2% under the irradiation of monochromatic light (λ = 420 nm). The recycling test of hydrogen evolution also verified a high stability for this dual heterojunction. The type-II band alignment and matched build-in electric field was confirmed, which accelerate the migration of charge carriers. The width of space-charge layer was calculated and proved that the p-n junctions in Cu2O/Ni(OH)2/TiO2 are fully-depleted, which largely reduced the bulk recombination of charge carriers. The synergistic effect of the improved visible-light response, type-II band alignment, matched build-in electric field, and fully-depleted space-charge layer contributes to the enhanced photocatalytic hydrogen evolution. Fully-depleted dual p-n heterojunctions of Cu2O/Ni(OH)2/TiO2 with band alignment and matched build-in electric field promoted the separation and transfer of the photo-generated charge carriers, thus improving the photocatalytic hydrogen evolution. [Display omitted] •Cu2O/Ni(OH)2/TiO2 with type-II alignment and matched electric field was fabricated.•Cu2O entended the visible-light absorption of Cu2O/Ni(OH)2/TiO2 photocatalyst.•Type-II alignment and matched electric field accelerated the carriers separation.•Fully-depleted p-n junctions reduced the bulk recombination of charge carriers.•Cu2O/Ni(OH)2/TiO2 exhibited high hydrogen evolution performance with an AQY of 20.2%.