CO₂ cycloaddition with epoxides at low temperature and pressure has been broadly recognized as an ambitious but challenging goal, which requires the catalysts to have precisely controlled Lewis acid sites. Here, we demonstrate that both stereochemical environment and oxidation state of single cobalt active sites in cobalt tetraaminophthalocyanine [CoPc(NH₂)₄] are finely tuned via molecular engineering with 2,5-di-tert-butyl-1,4-benzoquinone (DTBBQ). Notably, DTBBQ incorporation not only enables formation of 5-nm-thick conjugated microporous polymer (CMP) nanosheets due to the steric hindrance effect of tert-butyl groups but also makes isolated cobalt sites with high oxidation state due to the presence of delocalized electron-withdrawing effect of alkene groups in DTBBQ via conjugated skeleton. Notably, when used as heterogeneous catalysts for CO₂ cycloaddition with different epoxides, single cobalt active sites on the ultrathin CMP nanosheets exhibit unprecedentedly high activity and excellent stability under mild reaction conditions.

Numerous efforts are being made toward constructing artificial nanopockets inside heterogeneous catalysts to implement challenging reactions that are difficult to occur on traditional heterogeneous catalysts. Here, the enzyme-mimetic nanopockets are fabricated inside the typical UiO-66 by coordinating zirconium nodes with terephthalate (BDC) ligands and monocarboxylate modulators including formic acid (FC), acetic acid (AC), or trifluoroacetic acid (TFA). When used in transfer hydrogenation of alkyl levulinates with isopropanol toward γ-valerolactone (GVL), these modulators endow zirconium sites with enhanced activity and selectivity and good stability. The catalytic activity of UiO-66FC is ~30 times that of UiO-66, also outperforming the state-of-the-art heterogeneous catalysts. Distinct from general consensus on electron-withdrawing or electron-donating effect on the altered activity of metal centers, this improvement mainly originates from the conformational change of modulators in the nanopocket to assist forming the rate-determining six-membered ring intermediate at zirconium sites, which are stabilized by van der Waals force interactions.

Food is a necessity in people’s lives. Equally importantly, alcoholic beverages are also highly demanded globally due to the indispensable role they play in cultural, social, and ritual events. However, the production of food and alcoholic beverages suffers from a variety of contaminants, such as toxins, pesticides, antibiotic residues, and heavy metals, which are seriously harmful to human beings. These urgent threats have raised the awareness of the need to improve product quality and safety via developing effective, rapid, and economical monitoring and detecting methods. Fortunately, due to their numerous advantages, including high sensitivity, short response time, low cost, and easy portability, electrochemistry sensors have made huge contributions to ensuring the quality of food and alcoholic beverages. The purpose of this review is to introduce applications of electrochemical sensors to foods and alcoholic beverages, and to highlight the important role of carbon-based materials (i.e., carbon dots, carbon nanotubes, and graphene) as electrochemical sensors in detecting various contaminants. In addition, the preparation methods of these carbon-based electrochemical sensors and corresponding detection mechanisms are discussed in detail. It is hoped that this review can inspire more innovative detection technologies for ensuring the safety of food and alcoholic beverages.