Metal-free room-temperature phosphorescence (RTP) materials offer unprecedented potentials for photoelectric and biochemical materials due to their unique advantages of long lifetime and low toxicity. However, the achievements of phosphorescence at ambient condition so far have been mainly focused on ordered crystal lattice or on embedding into rigid matrices, where the preparation process might bring out poor repeatability and limited application. In this research, a series of amorphous organic small molecular compounds were developed with efficient RTP emission through conveniently modifying phosphor moieties to β-cyclodextrin (β-CD). The hydrogen bonding between the cyclodextrin derivatives immobilizes the phosphors to suppress the nonradiative relaxation and shields phosphors from quenchers, which enables such molecules to emit efficient RTP emission with decent quantum yields. Furthermore, one such cyclodextrin derivative was utilized to construct a host-guest system incorporating a fluorescent guest molecule, exhibiting excellent RTP-fluorescence dual-emission properties and multicolor emission with a wide range from yellow to purple including white-light emission. This innovative and universal strategy opens up new research paths to construct amorphous metal-free small molecular RTP materials and to design organic white-light-emitting materials using a single supramolecular platform.

Pd/H-ZSM-5 catalysts could completely catalyze CH 4 to CO 2 at as low as 320 °C, while there is no detectable catalytic activity for pure H-ZSM-5 at 320 °C and only a conversion of 40% could be obtained at 500 °C over pure H-ZSM-5. Both the theoretical and experimental results prove that surface acidic sites could facilitate the formation of active metal species as the anchoring sites, which could further modify the electronic and coordination structure of metal species. PdO x interacting with the surface Bronsted acid sites of H-ZSM-5 could exhibit Lewis acidity and lower oxidation states, as proven by the XPS, XPS valence band, CO-DRIFTS, pyridine FT-IR, and NH 3 -TPD data. Density functional theory calculations suggest PdO x groups to be the active sites for methane combustion, in the form of [AlO 2 ]Pd(OH)-ZSM-5. The stronger Lewis acidity of coordinatively unsaturated Pd and the stronger basicity of oxygen from anchored PdO x species are two key characteristics of the active sites ([AlO 2 ]Pd(OH)-ZSM-5) for methane combustion. As a result, the PdO x species anchored by Brønsted acid sites of H-ZSM-5 exhibit high performance for catalytic combustion of CH 4 over Pd/H-ZSM-5 catalysts.

A complete catalytic cycle for methane combustion on the Co3O4(110) surface was investigated and compared with that on the Co3O4(100) surface on the basis of first-principles calculations. It is found that the 2-fold coordinated lattice oxygen (O2c) would be of vital importance for methane combustion over Co3O4 surfaces, especially for the first two C–H bond activations and the C–O bond coupling. It could explain the reason the Co3O4(110) surface significantly outperforms the Co3O4(100) surface without exposed O2c for methane combustion. More importantly, it is found that the cooperation of homogeneous multiple sites for multiple elementary steps would be indispensable. It not only facilitates the hydrogen transfer between different sites for the swift formation of H2O to effectively avoid the passivation of the active low-coordinated O2c site but also stabilizes surface intermediates during the methane oxidation, optimizing the reaction channel. An understanding of this cooperation of multiple active sites not only might be beneficial in developing improved catalysts for methane combustion but also might shed light on one advantage of heterogeneous catalysts with multiple sites in comparison to single-site catalysts for catalytic activity.

White-light emission from a single molecule was realized and tuned via multistimuli including excitation, solvent polarity, temperature and host–guest interactions.