Zinc Oxide-Containing Porous Boron–Carbon–Nitrogen Sheets from Glycine–Nitrate Combustion: Synthesis, Self-Cleaning, and Sunlight-Driven Photocatalytic Activity

We developed a single-step thermal method that enables successful inclusion of ZnO components in the porous boron–carbon–nitrogen (BCN) framework to form a new class of functional hybrid. ZnO-containing BCN hybrids were prepared by treating a mixture of B₂O₃, glycine, and zinc nitrate at 500 °C. Glycine–nitrate decomposition along with B₂O₃ acts as a source for ZnO-BCN formation. The incorporation of ZnO onto BCN has extended the photoresponse of ZnO in the visible region, which makes ZnO-BCN a preferable photocatalyst relative to ZnO upon sunlight exposure. It is interesting to note that as-prepared 2D ZnO-BCN sheets dispersed in PDMS form a stable coating over aluminum alloys. The surface exhibited a water contact angle (CA) of 157.6° with 66.6 wt % ZnO-BCN in polydimethylsiloxane (PDMS) and a water droplet (7 μL) roll-off angle of <6° and also demonstrates oil fouling resistant superhydrophobicity. In brief, the present study focuses on the gram scale synthesis of a new class of sunlight-driven photocatalyst and also its application toward the development of superhydrophobic and oleophobic coating

Local Environments of Dilute Activator Ions in the Solid-State Lighting Phosphor Y_3–<i>x</i>Ce_<i>x</i>Al₅O₁₂

The oxide garnet Y₃Al₅O₁₂ (YAG), when substituted with a few percent of the activator ion Ce³⁺ to replace Y³⁺, is a luminescent material that is nearly ideal for phosphor-converted solid-state white lighting. The local environments of the small number of substituted Ce³⁺ ions are known to critically influence the optical properties of the phosphor. Using a combination of powerful experimental methods, the nature of these local environments is determined and is correlated with the macroscopic luminescent properties of Ce-substituted YAG. The rigidity of the garnet structure is established and is shown to play a key role in the high quantum yield and in the resistance toward thermal quenching of luminescence. Local structural probes reveal compression of the Ce³⁺ local environments by the rigid YAG structure, which gives rise to the unusually large crystal-field splitting, and hence yellow emission. Effective design rules for finding new phosphor materials inferred from the results establish that efficient phosphors require rigid, highly three-dimensionally connected host structures with simple compositions that manifest a low number of phonon modes, and low activator ion concentrations to avoid quenching