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Metal oxide catalysts' performance depends on their crystal structure, including the surface arrangement and coordination of metal cations and oxygen anions on the exposed facets. Here, we fabricated Co3O4 nanocrystals (NCs) with predominantly exposed (110), (111), (112), and (114) facets in the shapes of nanorod (Co-R), hexagonal nanoplate (Co-H), nanolaminar (Co-L), and nanoparticle (Co-P), respectively. The Co3O4 NC with exposed (114) high-index facet exhibits the highest 5-hydroxymethylfurfural (HMF) electrocatalytic activity, while the Co3O4 NC with exposed (112) shows the lowest activity. Both density functional theory (DFT) calculations and experiments reveal that the primary factor impacting the catalytic performance of Co3O4 NCs is the difference in HMF adsorption energy on various crystal facets. By doping Cr into Co3O4 (114), we tuned the adsorption energy of HMF to an optimal level, thereby achieving the best catalytic performance. Based on this, the adsorption behavior of other aldehyde–alcohol organic small molecules was also evaluated, and the linear relationship between adsorption strength and catalytic activity was confirmed. This work demonstrates that adjusting the exposed crystal facets of Co3O4 can alter the adsorption and catalytic capabilities of aldehyde–alcohol organic small molecules. It also provides explicit knowledge that could improve our understanding of facet-dependent reactions for other metal oxide catalysts. [ABSTRACT FROM AUTHOR]

The CO2-involved synthesis of chemicals is of great significance from the green and sustainable chemistry viewpoint. Herein, we report a non-noble metal catalytic system composed of CoF2, CsF and P(CH2CH2PPh2)3 (denoted as PP3) for the synthesis of N-containing heterocycles from ortho-substituted anilines and CO2/H2. Mechanism investigation indicates that [Co(PP3)H(CO2)]+ is a catalytically active intermediate under working conditions; and CsF plays important roles in activating ortho-substituted anilines via hydrogen bond interactions, thus promoting the formation of the final products. This catalytic system is highly efficient, and allows a wide scope of ortho-substituted anilines, together with excellent functional group tolerance, affording various N-containing heterocycles in good to excellent yields. [ABSTRACT FROM AUTHOR]

A metal-free and highly efficient catalytic system involving a task-specific ionic liquid, [P4444][p-2-O], and a pyrene-based conjugated polymer was developed for direct CO2 capture from air and its further photoreduction to CO under visible light irradiation, affording a CO production rate of 47.37 μmol g−1 h−1 with a selectivity of 98.3%. [ABSTRACT FROM AUTHOR]

Herein the reductive amination/cyclization of levulinic acid using phenylsilane was presented to selectively produce pyrrolidones versus pyrrolidines under mild conditions by switching the catalyst from AlCl3 to RuCl3. Using AlCl3 as the catalyst, pyrrolidones were solely obtained at room temperature, while RuCl3 as the catalyst selectively afforded pyrrolidines in high yields at 45 °C. [ABSTRACT FROM AUTHOR]

The CO2-involved synthesis of chemicals is of great significance from the green and sustainable chemistry viewpoint. Herein, we report a non-noble metal catalytic system composed of CoF2, CsF and P(CH2CH2PPh2)3 (denoted as PP3) for the synthesis of N-containing heterocycles from ortho-substituted anilines and CO2/H2. Mechanism investigation indicates that [Co(PP3)H(CO2)]+ is a catalytically active intermediate under working conditions; and CsF plays important roles in activating ortho-substituted anilines via hydrogen bond interactions, thus promoting the formation of the final products. This catalytic system is highly efficient, and allows a wide scope of ortho-substituted anilines, together with excellent functional group tolerance, affording various N-containing heterocycles in good to excellent yields. [ABSTRACT FROM AUTHOR]