Surface-Confined Atomic Silver Centers Catalyzing Formaldehyde Oxidation

Formaldehyde (HCHO) is a prior pollutant in both indoor and outdoor air, and catalytic oxidation proves the most promising technology for HCHO abatement. For this purpose, supported metal catalysts with single silver atoms confined at 4-fold O₄-terminated surface hollow sites of a hollandite manganese oxide (HMO) as catalytic centers were synthesized and investigated in the complete oxidation of HCHO. Synchrotron X-ray diffraction patterns, X-ray absorption spectra, and electron diffraction tomography revealed that geometric structures and electronic states of the catalytic centers were tuned by the changes of HMO structures via controllable metal–support interactions. The catalytic tests demonstrated that the catalytically active centers with high electronic density of states and strong redox ability are favorable for enhancement of the catalytic efficiency in the HCHO oxidation. This work provides a strategy for designing efficient oxidation catalysts for controlling air pollution

Surface-Confined Atomic Silver Centers Catalyzing Formaldehyde Oxidation

Formaldehyde (HCHO) is a prior pollutant in both indoor and outdoor air, and catalytic oxidation proves the most promising technology for HCHO abatement. For this purpose, supported metal catalysts with single silver atoms confined at 4-fold O₄-terminated surface hollow sites of a hollandite manganese oxide (HMO) as catalytic centers were synthesized and investigated in the complete oxidation of HCHO. Synchrotron X-ray diffraction patterns, X-ray absorption spectra, and electron diffraction tomography revealed that geometric structures and electronic states of the catalytic centers were tuned by the changes of HMO structures via controllable metal–support interactions. The catalytic tests demonstrated that the catalytically active centers with high electronic density of states and strong redox ability are favorable for enhancement of the catalytic efficiency in the HCHO oxidation. This work provides a strategy for designing efficient oxidation catalysts for controlling air pollution

Series of Metal Organic Frameworks Assembled from Ln(III), Na(I), and Chiral Flexible-Achiral Rigid Dicarboxylates Exhibiting Tunable UV–vis–IR Light Emission

Two series of isoreticular chiral metal–organic frameworks assembled from Ln­(III) (Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb), Na­(I), and chiral flexible-achiral rigid dicarboxylate ligands, formulated as [NaLn­(Tart)­(BDC)­(H₂O)₂] (<b>S1</b>) and [NaLn­(Tart)­(biBDC)­(H₂O)₂] (<b>S2</b>) (H₂Tart = tartaric acid; H₂BDC = terephthalic acid; H₂biBDC = biphenyl-4,4′-dicarboxylic acid), were obtained as single phases under hydrothermal conditions. The compounds have been studied by single-crystal and powder X-ray diffraction, thermal analyses (TG-MS and DSC), vibrational spectroscopy (FTIR), scanning electron microscopy (SEM-EDX), elemental analysis, and X-ray thermodiffractometry. The catalytic activity has been also investigated. The photoluminescence properties of selected compounds have been investigated, exhibiting room temperature tunable UV–vis–IR light emission

Series of Metal Organic Frameworks Assembled from Ln(III), Na(I), and Chiral Flexible-Achiral Rigid Dicarboxylates Exhibiting Tunable UV–vis–IR Light Emission

Two series of isoreticular chiral metal–organic frameworks assembled from Ln­(III) (Ln = Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb), Na­(I), and chiral flexible-achiral rigid dicarboxylate ligands, formulated as [NaLn­(Tart)­(BDC)­(H₂O)₂] (<b>S1</b>) and [NaLn­(Tart)­(biBDC)­(H₂O)₂] (<b>S2</b>) (H₂Tart = tartaric acid; H₂BDC = terephthalic acid; H₂biBDC = biphenyl-4,4′-dicarboxylic acid), were obtained as single phases under hydrothermal conditions. The compounds have been studied by single-crystal and powder X-ray diffraction, thermal analyses (TG-MS and DSC), vibrational spectroscopy (FTIR), scanning electron microscopy (SEM-EDX), elemental analysis, and X-ray thermodiffractometry. The catalytic activity has been also investigated. The photoluminescence properties of selected compounds have been investigated, exhibiting room temperature tunable UV–vis–IR light emission

Consequences of Nitrogen Doping and Oxygen Enrichment on Titanium Local Order and Photocatalytic Performance of TiO₂ Anatase

Extended X-ray absorption fine structure (EXAFS) investigation of the oxygen-rich titania formed via the thermal treatment of N-doped TiO₂ has revealed that the removal of N-dopants is responsible for the creation of defect sites in the titanium environment, thus triggering at high temperatures (500–800 °C) the capture of atmospheric oxygen followed by its diffusion toward the vacant sites and formation of interstitial oxygen species. The effect of the dopants on Ti coordination number and Ti–O_int and Ti–N_int bond distances has been estimated. The photocatalytic <i>p</i>-cresol degradation tests have demonstrated that the interband states formed by the N-dopants contribute to a greater extent to the visible-light activity than the oxygen interstitials do. However, under the UV irradiation the oxygen-rich titania shows higher efficiency in the pollutant degradation, while the N-dopants in N–TiO₂ play the role of recombination sites. The presence of the surface nitrogen species in TiO₂ is highly beneficial for the application in partial photooxidation reactions, where N–TiO₂ demonstrates a superior selectivity of 5-hydroxymethyl furfural (HMF) oxidation to 2,5-furandicarbox­aldehyde (FDC). Thus, this work underlines the importance of a rational design of nonmetal doped titania for photocatalytic degradation and partial oxidation applications, and it establishes the role of bulk defects and surface dopants on the TiO₂ photooxidation performance