UiO-66 is a highly important prototypical zirconium metal−organic framework (MOF) compound because of its excellent stabilities not typically found in common porous MOFs. In its perfect crystal structure, each Zr metal center is fully coordinated by 12 organic linkers to form a highly connected framework. Using high-resolution neutron power diffraction technique, we found the first direct structural evidence showing that real UiO-66 material contains significant amount of missing-linker defects, an unusual phenomenon for MOFs. The concentration of the missinglinker defects is surprisingly high, ∼10% in our sample, effectively reducing the framework connection from 12 to ∼11. We show that by varying the concentration of the acetic acid modulator and the synthesis time, the linker vacancies can be tuned systematically, leading to dramatically enhanced porosity. We obtained samples with pore volumes ranging from 0.44 to 1.0 cm 3 / g and Brunauer−Emmett−Teller surface areas ranging from 1000 to 1600 m 2 /g, the largest values of which are ∼150% and ∼60% higher than the theoretical values of defect-free UiO-66 crystal, respectively. The linker vacancies also have profound effects on the gas adsorption behaviors of UiO-66, in particular CO 2 . Finally, comparing the gas adsorption of hydroxylated and dehydroxylated UiO-66, we found that the former performs systematically better than the latter (particularly for CO 2 ) suggesting the beneficial effect of the −OH groups. This finding is of great importance because hydroxylated UiO-66 is the practically more relevant, non-air-sensitive form of this MOF. The preferred gas adsorption on the metal center was confirmed by neutron diffraction measurements, and the gas binding strength enhancement by the −OH group was further supported by our firstprinciples calculations. ■ INTRODUCTIONMetal−organic frameworks (MOFs), consisting of inorganic metal centers connected by organic linkers, are a relatively new family of porous materials that possess rich chemistry and offer great promise for gas adsorption related applications.

2D materials have shown great promise for next-generation high-performance photodetectors. However, the performance of photodetectors based on 2D materials is generally limited by the tradeoff between photoresponsivity and photodetectivity. Here, a novel junction field-effect transistor (JFET) photodetector consisting of a PdSe 2 gate and MoS 2 channel is constructed to realize high responsivity and high detectivity through effective modulation of top junction gate and back gate. The JFET exhibits high carrier mobility of 213 cm 2 V −1 s −1 . What is more, the high responsivity of 6 × 10 2 A W −1 , as well as the high detectivity of 10 11 Jones, are achieved simultaneously through the dual-gate modulation. The high performance is attributed to the modulation of the depletion region by the dual-gate, which can effectively suppress the dark current and enhance the photocurrent, thereby realizing high detectivity and responsivity. The JFET photodetector provides a new approach to realize photodetectors with high responsivity and detectivity.

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