Rational construction of S-scheme BN/MXene/ZnIn₂S₄ heterojunction with interface engineering for efficient photocatalytic hydrogen production and chlorophenols degradation

Achieving structural optimization and component modulation in ZnIn₂S₄-based photocatalysts while performing photocatalytic hydrogen evolution and degradation performance is a great challenge. In this work, a BN/MXene/ZnIn₂S₄ S-scheme photocatalytic heterojunction was obtained by growing the etched BN/MXene on the ZnIn₂S₄ nanosheets directly. Among them, introducing a special electron trapping effect of MXene successfully avoids the photocatalytic inferiority caused by the broader band gap of BN with weak conductivity and poor photocatalytic response activity. Therefore, a stable photocatalytic heterojunction can be constructed by adding MXene. The S-scheme heterojunction was identified by UPS, EPRS, VB-XPS and Mott-Schottky measurements. The bifunctional composite heterojunction photocatalyst exhibited excellent hydrogen production performance (∼1455 μmol·g⁻¹·h⁻¹) and 4-chlorophenol (4-CP) degradation ability (90 %) with good stability compared to the that of pure BN/MXene and the ZnIn₂S₄ samples. In particular, the formation of a built-in electric field at the interface between BN/MXene and ZnIn₂S₄ n-type semiconductors provides directional acceleration of effective separation of the photogenerated charges and preserves excellent redox capability of the semiconductors. With the excellent hydrogen production performance and 4-CP degradation efficiency of the constructed bifunctional BN/MXene/ZnIn₂S₄ heterojunction, this work provides a feasible strategy for constructing an S-scheme heterojunction for energy and environmental remediation.