Microwave assisted synthesis of PQ-GDY@NH_(2)-UIO-66(Zr) for improved photocatalytic removal of NOx under visible light

Pyrazinoquinoxaline-based graphdiyne (PQ-GDY) contains a fixed number of sp-sp2hybridized carbon atoms and pyrazine-like sp2hybridized N atoms.In this paper,NH_(2)-UIO-66(Zr) on PQ-GDY substrate was successfully constructed with the help of microwaveassisted heating.PQ-GDY surface acts as a microwave antenna under microwave irradiation to rapidly absorb microwave energy and form hot spots (hot spot effect),which facilitates the formation of well-dispersed NH2-UIO-66(Zr) with good crystallinity.Transient absorption spectra show that high hole transport property of PQ-GDY can accelerate the migration of photogenerated holes from NH2-UIO-66(Zr) to PQ-GDY and greatly reduce the recombination rate of photogenerated electrons and holes due to the strong interaction between PQ-GDY and NH2-UIO-66(Zr).Under visible light (λ≥420 nm),PQ-GDY@NH_(2)-UIO-66(Zr) shows high photocatalytic stability and high NO_(x)removal rate up to 74%,which is 44% higher than that of primitive NH_(2)-UIO-66(Zr).At the same time,it inhibits the formation of toxic byproducts (NO2) and limits its concentration to a low level.

A Stable Luminescent Covalent Organic Framework Nanosheet for Sensitive Molecular Recognition

Despite rapid advances in fluorescence detectors over the past decade,the development of a highly stable,sensitive,and selective fluorescence platform for molecular recognition remains a considerable challenge.Here we report a stable carbazole-based sp2 carbon fluorescence covalent organic framework(COF)nanosheet,termed a JUC-557 nanosheet.Owing to the synergistic effect of aggregation-induced emission-and aggregation-caused quenching-based chromophores,the architecture of the JUC-577 shows high absolute quantum yields(up to 23.0%)in the solid state and when dispersed in various solvents as well as excellent sensing performance toward specific analytes,such as iodine(Ka:2.10×10^(5)M−1 and LOD:302 ppb),2,4,6-trinitrotoluene(Ka:4.38×10^(5)M−1 and LOD:129 ppb),and especially nitrobenzene(Ka:6.18×10^(6)M−1 and LOD:5 ppb)that is superior to that of fluorescence detection materials reported so far.Furthermore,the JUC-557 nanosheet preserves strong luminescence and sensitive recognition,even under harsh conditions,and allows trace detection of various analytes via a handheld UV lamp.These findings pave the way for developing stable ultrathin COF nanomaterials for highly sensitive and selective molecular detection.