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The development of novel catalysts for the synthesis of cyclic carbonates under mild conditions remains a challenge. Herein, we designed the strategy of immobilizing DBU-based ionic liquid on mesoporous SBA-15 (DBU@SBA-15), due to the cooperative effect between silanol and bromide anion, DBU@SBA-15 exhibits high CO2 catalytic performance under solvent-free and metal-free and additive-free conditions. Typically, the yield of chloropropene carbonate was close to 100% from the reaction of epichlorohydrin and CO2 within 12 h at 80 °C and 2 MPa. Notably, the product yield could achieve 64.8% even at ambient pressure, and DBU@SBA-15 was recycled four times without significant loss of catalytic activity. Additionally, DFT studies revealed that the nucleophilic effect and the strong hydrogen bond together promote the ring-opening of epoxides, which was consistent with the possible reaction mechanism proposed based on experiments. [ABSTRACT FROM AUTHOR]

Hg2+ is a serious environmental contaminant that can cause severe damage to the immune and nervous systems, and Hg2+ monitoring is critical. Herein, we report a novel, simple, and sensitive Hg2+ sensor based on the enhanced peroxidase‐like activity of chitosan–gold nanoparticles (CS‐AuNPs). The peroxidase‐like activity of the CS‐AuNPs can be markedly enhanced by Hg2+ as seen by the deeper color and increased absorbance at 652 nm. This improved catalytic ability was used to develop a sensitive and selective colorimetric sensor for Hg2+ detection. The limit of detection via the absorption spectra is as low as 0.02 μM. The mechanism underlying the enhanced catalytic ability is discussed. This approach is label‐free, simple, and offers detection with the naked eye. Thus, it has potential applications for the detection of Hg2+ in environmental and food samples. [ABSTRACT FROM AUTHOR]