Interfacial CoOx Layers on TiO2 as an Efficient Catalyst for Solvent-Free Aerobic Oxidation of Hydrocarbons

Efficient C(sp3)-H Bond Oxidation on Perovskite Quantum Dots Based on Ce-Oxygen Affinity

Perovskite quantum dots (QDs) have shown attractive prospects in the field of visible photocatalysis, especially in the synthesis of high value-added chemicals. However, under aerobic conditions, the stable operation of QD catalysts has been limited by the reactive oxygen species (ROS) generated by photoexcitation, especially superoxide species O2⋅-. Here, we propose a strategy of Ce3+ doping in perovskite QDs to guide superoxide species for photocatalytic oxidation reactions. In C(sp3)-H bond oxidation of hydrocarbons, superoxide species were rapidly generated and efficiently utilized on the surface of perovskite QDs, which achieves the stable operation of the catalytic system and obtains a high product conversion rate (15.3 mmol/g/h for benzaldehydes). The mechanism studies show that the strong Ce-oxygen affinity accelerates the relaxation process of photoinduced exciton transfer to superoxide species and inhibits the radiative recombination pathway. This work provides a new idea of utilizing oxygen species on perovskite surface and broadens the design strategy of high-performance QD photocatalysts.

Selective Aerobic Oxidation of Csp3-H Bonds Catalyzed by Yeast-Derived Nitrogen, Phosphorus, and Oxygen Codoped Carbon Materials

Nitrogen, phosphorus, and oxygen codoped carbon catalysts were successfully synthesized using dried yeast powder as a pyrolysis precursor. The yeast-derived heteroatom-doped carbon (yeast@C) catalysts exhibited outstanding performance in the oxidation of C_sp³-H bonds to ketones and esters, giving excellent product yields (of up to 98% yield) without organic solvents at low O₂ pressure (0.1 MPa). The catalytic oxidation protocol exhibited a broad range of substrates (38 examples) with good functional group tolerance, excellent regioselectivity, and synthetic utility. The yeast-derived heteroatom-doped carbon catalysts showed good reusability and stability after recycling six times without any significant loss of activity. Experimental results and DFT calculations proved the important role of N-oxide (N⁺-O^-) on the surface of yeast@C and a reasonable carbon radical mechanism.

Mechanistic insights into CoOx–Ag/CeO2 catalysts for the aerobic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid

CoOx–Ag/CeO2 catalysts achieve satisfactory FDCA yield from HMF, and a fundamental understanding about the reaction mechanism is provided.

Methane Activation by the Heteronuclear Cluster [TiAlO4]+: Direct Hydrogen Abstraction by a Nonradical Oxygen

The gas-phase reactions of [TiAlO₄]⁺ with methane have been explored by using FT-ICR mass spectrometry complemented by quantum chemical calculations. Interestingly, the [TiAlO₄]⁺ ions can activate two methane molecules continuously. Moreover, in contrast to the previous reports on gas-phase methane activation by metal oxide clusters, in which hydrogen-atom transfer and/or proton-coupled electron transfer prevail, a hydride transfer process dominates the [TiAlO₄]⁺/CH₄ system. The associated electronic origins have been discussed, and such a terminal metal-oxo active center as addressed in the [TiAlO₄]⁺ cluster has proven to be promising in the construction of efficient catalysts concerning methane conversion.

Synthesis and Catalytic Properties of Porous Metal Silica Materials Templated and Functionalized by Extended Coordination Cages

A practically applicable strategy is developed to rationally immobilize easily accessed and highly dispersed redox-active metal oxides into porous metal silica (PMS) materials templated and functionalized by porous metal-ligand moieties. On the basis of this strategy, the highly active porous catalyst PMS-1 is successfully targeted for aerobic oxidation of cyclohexane with conversion up to 14.6%, which is much superior to the current industrially adopted catalysts (less than 4% cyclohexane conversion) that use harsh conditions. This promising approach to explore highly active heterogeneous catalysts for inert C-H bond activation should lead to the further discovery of numerous industrially useful catalysts for the oxidation of inert hydrocarbon raw materials.