2D CeO2 and a Partially Phosphated 2D Ni-Based Metal-Organic Framework Formed an S-Scheme Heterojunction for Efficient Photocatalytic Hydrogen Evolution

Here, an S-scheme heterojunction was constructed on the basis of the modification of a Ni-based metal-organic framework (Ni-MOF) by different in situ treatment strategies. First, NiS2, NiO, and Ni2P were derived in situ on the surface of Ni-MOF through surface sulfonation, oxidation, and phosphatizing treatments. They can efficiently accept the electrons from the conduction band of Ni-MOF as the trap centers, thus improving the hydrogen production activity. Additionally, phosphatizing makes the electronegativity of Ni-MOF/P stronger than that of the original Ni-MOF, which can enhance the absorption of protons, thus promoting the hydrogen evolution reaction. Next, the S-scheme heterojunction was successfully built by the coupling of 2D CeO2 with Ni-MOF/P. The maximum hydrogen production rate of the hybrid catalyst (6.337 mmol g(-1) h(-1)) is 14.18 times that of the untreated Ni-MOF due to the full utilization of photo-induced electrons. Finally, the probable hydrogen evolution mechanism was proposed by analyzing a series of characterization results and by the density functional theory (DFT) calculation.

Automated summary

An S-scheme heterojunction was constructed by modifying the surface of Ni-based metal-organic framework (Ni-MOF) through different in situ treatment strategies. The in situ formation of NiS2, NiO, and Ni2P on the Ni-MOF surface improved the hydrogen production activity by accepting electrons from the conduction band of Ni-MOF. Coupling 2D CeO2 with Ni-MOF/P successfully built the S-scheme heterojunction, leading to a significantly higher hydrogen production rate.