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

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 indi-vidual p-n heterojunction. Photocatalytic hydrogen evolution under the simulated sunlight shows a high rate of 6145 mmol 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 (lambda = 420 nm). The recycling test of hydrogen evolution also verified a high stability for this dual hetero-junction. 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. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

A dual p-n heterojunction of Cu2O/Ni(OH)(2)/TiO2 was fabricated with type-II band alignment and matched build-in electric field, promoting efficient charge separation and transfer for enhanced photocatalytic hydrogen evolution. The synergistic effect of improved visible-light response, type-II band alignment, matched build-in electric field, and fully-depleted space-charge layer contributes to the enhanced performance.