New electron transport path created by S-doped NH2-UiO-66 bridged ZnIn2S4/MoS2 nanosheet heterostructure for boosting photocatalytic hydrogen evolution

Developing well-designed architectures plays a decisive role in accelerating photon-generated carriers transport in the composite photocatalysts. Herein, a microporous sulfur-doped (S-doped) NH2-UiO-66 bridged ZnIn2S4/MoS2 sheet heterostructure photocatalyst is synthesized through thermolysis of sulfur rich precursors to functionalize organic ligands of NH2-UiO-66 to boost photocatalytic efficiency. XPS spectra confirms the existence of S-doping NH2-UiO-66, and Raman spectra demonstrates transition metal–assisted sulfuration instead of carbonization. FT-IR spectra further confirms the formation of Zn-O-C covalent bonds at the interface between NH2-UiO-66 and ZnIn2S4. Especially, the Zn-O-C bonds preserve the energy of photo-generated electrons and inhibit the energy relaxation of electrons at the interface of heterostructure interface. In addition, the NH2-UiO-66 with highly photocatalytic response not only as an electron transport bridge but also an electron donor greatly facilitates the transport of photo-generated electrons. Profiting from the unique design of ternary composite, the sample exhibits excellent PHE performance. The obtained ZnIn2S4/NH2-UiO-66/5%-MoS2 (5.69 mmol·h-1·g-1) exhibits the highest H2 evolution rate, which is 15 and 1.9 times than those of ZnIn2S4 (0.369 mmol·h-1·g-1) and 5%-MoS2/ ZnIn2S4 (2.93 mmol·h-1·g-1), respectively. In addition, the apparent quantum efficiency of ZnIn2S4/NH2-UiO-66/5%-MoS2 composite (7.95%) exhibits higher than 5%-MoS2/ZnIn2S4 composite (3.12%) at 420 nm. This work provides new insight for designing novel and high-efficient photocatalysts for photocatalytic hydrogen evolution.