Step-by-Step Improving Photocatalytic Hydrogen Evolution Activity of NH2–UiO-66 by Constructing Heterojunction and Encapsulating Carbon Nanodots

Carbon nanodots (CDs) have attracted enormous attention in the photocatalytic area for their high light-harvesting and outstanding electron transfer abilities. In this work, NH2–UiO-66 was first composited with g-C3N4 to construct an NH2–UiO-66/g-C3N4 heterojunction. Then, CDs were incorporated into the pores of NH2–UiO-66 by the pore space of the framework serving as confined nanoreactors to construct a CD@NH2–UiO-66/g-C3N4 ternary composite. The ultrasmall CDs transformed from incapsulated glucose in the pores of NH2–UiO-66 were uniformally distributed in MOFs and extensively improve the photocatalytic hydrogen evolution activity of the composite under visible-light irradiation. The optimum photocatalytic H2 evolution rate of the CD@NH2–UiO-66/g-C3N4 composite with a CD content of 2.77 wt % is 2.930 mmol·h–1·g–1 under visible-light irradiation, which is 32.4, 38.6, and 17.5 times as high as that of bulk g-C3N4, NH2–UiO-66, and NH2–UiO-66/g-C3N4, respectively. The remarkable enhancement of the photocatal...