Enhanced transformation of CO2 over microporous Ce-doped Zr metal-organic frameworks

Comparative Study between 2-Furonitrile and 2-Cyanopyridine as Dehydrants in Direct Synthesis of Dialkyl Carbonates from CO2 and Alcohols over Cerium Oxide Catalyst

The shift of equilibrium by removing water with nitrile dehydrants is crucial for CeO2 -catalyzed synthesis of dialkyl carbonates from CO2 and alcohols. Two nitriles - 2-cyanopyridine and 2-furonitrile - were previously found as effective dehydrants, yet their detailed comparison as well as exploration of potential of 2-furonitrile remain insufficient. Herein, the performance of 2-cyanopyridine and 2-furonitrile was compared in the synthesis of various dialkyl carbonates. 2-furonitrile was found to be superior to 2-cyanopyridine in the synthesis of dialkyl carbonates from CO2 and bulky or long-chain (≥C3) alcohols. Namely, the yield of diisopropyl carbonate (up to 50 %) achieved using CeO2 and 2-furonitrile is comparable to or even higher than previously reported ones. Meanwhile, 2-cyanopyridine acted as a better dehydrant than 2-furonitrile in the synthesis of dimethyl carbonate and diethyl carbonate. The adsorption experiments and density functional theory calculations have indicated that the better performance of 2-furonitrile compared to 2-cyanopyridine in the synthesis of dialkyl carbonates from bulky or long-chain alcohols is due to the weaker interaction of 2-furonitrile with the CeO2 surface. Such weak interaction of 2-furonitrile offers a larger reaction field on the catalyst surface for both CO2 and alcohols.

Ce/Zr-MOF with Dual Cycle Synergistic Catalysis Pathway Enabling Enhanced Peroxidase-like Performance for Wearable Hydrogel Patch Visualization Sensing Platform

Engineering the activity of enzyme-like catalysts should be a top priority to make them superior substitutes for natural enzymes. Herein, a Ce/Zr bimetal-organic framework (Ce/Zr-MOF) was designed and synthesized by a one-pot hydrothermal method, which has enhanced performance in mimicking peroxidase (POD) than its single-metal counterparts. To further comprehend the mechanism of activity enhancement, the role of the bimetallic synergistic catalysis process in H2O2 decomposition and reactive oxygen species formation was elucidated, and the possible dual cycle synergistic catalysis pathway of bimetallic catalysis is proposed for the first time. The enhanced POD-like activity mainly depends on the introduction of Ce, which improved the conductivity and electron-transfer capability of Ce/Zr-MOF and promoted the generation of •OH. Integrated with a hydrogel substrate, a wearable all-solid-state H2O2 sensor for early diagnosis of plant health was produced. The detection limit can be as low as 3.3 μM, which is lower than that of some instrument-based colorimetric methods and has great potential in the development of visualized sensing applications. The concept of dual cycle synergistic catalysis pathway we proposed not only deepens the comprehension regarding sensing and catalytic mechanisms but also provides novel perspectives into the design of enzyme-like catalysts for extensive usage.

Thermocatalytic Conversion of CO2 to Valuable Products Activated by Noble-Metal-Free Metal-Organic Frameworks

Thermocatalysis of CO2 into high valuable products is an efficient and green method for mitigating global warming and other environmental problems, of which Noble-metal-free metal-organic frameworks (MOFs) are one of the most promising heterogeneous catalysts for CO2 thermocatalysis, and many excellent researches have been published. Hence, this review focuses on the valuable products obtained from various CO2 conversion reactions catalyzed by noble-metal-free MOFs, such as cyclic carbonates, oxazolidinones, carboxylic acids, N-phenylformamide, methanol, ethanol, and methane. We classified these published references according to the types of products, and analyzed the methods for improving the catalytic efficiency of MOFs in CO2 reaction. The advantages of using noble-metal-free MOF catalysts for CO2 conversion were also discussed along the text. This review concludes with future perspectives on the challenges to be addressed and potential research directions. We believe that this review will be helpful to readers and attract more scientists to join the topic of CO2 conversion.