Metal–Organic Framework-Ag Nanocomposites as\nPhotocatalysts and in Situ Surface-Enhanced Raman Spectroscopy Sensors\nto Study the Mechanisms of CO<sub>2</sub> Reduction Reactions

Nanocomposites could\ncombine the advantages of various materials,\nallowing them to be used to achieve special applications that cannot\nbe achieved with a single material. Here, nanocomposites composed\nof plasmonic nanocrystal (silver nanocube, AgNC) and metal–organic\nframeworks (ZIF-8 or metal–organic framework (MOF)-801) had\nthe advantages of excellent surface-enhanced Raman spectroscopy (SERS)\nperformance and high CO<sub>2</sub> reduction activity of AgNC and\nexcellent CO<sub>2</sub> capture performance of MOFs, which enabled\nthese nanocomposites to be used as an in situ SERS sensor to detect\nCO<sub>2</sub> reduction. The results showed that the CO<sub>2</sub> adsorption performance of MOF-AgNC nanocomposites strongly depended\non the thickness of the MOF shell and the internal environment of\nthe MOF, and these nanocomposites as CO<sub>2</sub> reduction photocatalysts\ncan produce different products, which were strongly dependent on the\nenvironment of the MOF-AgNC interface. The rate-determining step of\nCO<sub>2</sub> reduction in different MOF-AgNC nanocomposite systems\nalso exhibited differences, which can be attributed to the different\nMOF and CO<sub>2</sub> interactions. These results demonstrated that\nMOF-AgNC nanocomposites are feasible as an in situ SERS sensor for\nobserving CO<sub>2</sub> reduction, which makes it possible to design\ndifferent nanocomposites as suitable in situ Raman spectroscopy sensors\nto detect various chemical reactions.