Promoting photocarriers separation in S-scheme system with Ni2P electron bridge: The case study of BiOBr/Ni2P/g-C3N4

Constructing step-scheme (S-scheme) heterojunctions can considerably facilitate separation and transfer of photocarriers, as well as promote strong redox ability. The interface resistance of heterojunctions immediately affects photocarrier separation and determines the photocatalytic activity. Herein, we constructed a novel BiOBr/Ni2P/g-C3N4 heterojunction using Ni2P as a novel electron bridge to reduce the interfacial resistance of photocarriers between BiOBr and g-C3N4. The as-prepared 10% BiOBr/Ni2P/g-C3N4 sample exhibited outstanding visible-light photocatalytic performance for methyl orange and rhodamine B removal, with degradation efficiencies of 91.4% and 98.9%, respectively. The excellent photocatalytic activity of BiOBr/Ni2P/g-C3N4 was mainly attributed to the synergistic effects of the Ni2P cocatalyst and S-scheme heterojunction, which not only reduced the interface resistance but also retained the strong redox potential of the photocarriers. In addition, the formation of the S-scheme system was supported by active oxygen species investigation, current-voltage curves, and density functional theory calculations. This work provides a guideline for the design of highly efficient S-scheme photocatalysts with transition metal phosphates as electron bridges to improve photocarriers separation.