An effective strategy for improving charge separation efficiency and photocatalytic degradation performance using a facilely synthesized oxidative TiO2 catalyst.

Titanium dioxide (TiO2) has attracted enormous interest in abundant photocatalytic reactions, but its photocatalytic efficiency is limited by its wide bandgap and the rapid recombination of electron-hole pairs. To overcome the disadvantages of its rapid electron-hole recombination rate, herein, oxidative TiO2 was one-step fabricated using potassium permanganate (KMnO4), exhibiting improved charge separation efficiency and photocatalytic degradation performance towards methyl orange (MO). Remarkably, the first-order photodegradation rate of oxidative TiO2 is 3.68 times higher than that of pristine TiO2 under the irradiation of simulated sunlight and 2.15 times higher under ultraviolet light. This exceptional photocatalytic activity is attributed to the additional oxygen doped into the interstices of the TiO2 lattice, creating impurity states in the bandgap acting as trapping sites, thus facilitating charge separation. This work provides a promising strategy for the insertion of O atoms into the TiO2 lattice and expands the photocatalytic application of the related materials.

Five monocyclic pyridinium derivative based halo-argentate/cuprate hybrids or iodide salts: influence of composition on photochromic behaviors.

The rational choice of an electron acceptor was proved to be an effective strategy for the development of novel electron transfer (ET) photochromic iodides, but the types and amounts of reported electron acceptors are relatively limited so far, especially for monocyclic aromatic molecules. Herein, using monocyclic pyridinium derivatives (N-protonation-4-carboxypyridinium/N-protonation-4-carbamoylpyridinium/1-methyl-4-(carbomethoxy)pyridinium) as structural directing agents and electron acceptors, five new electron donor-acceptor-based halo-argentate/cuprate hybrids or iodide salts have been synthesized, including [HINA][Ag4I5] (1), [HINAM]I (2), [HINAM]I·0.5(I2) (3), [MCMP][Ag2Br3] (4) and [MCMP][Cu2I3] (5). Noteworthily, compounds 1-3 exhibit interesting photochromic behaviours, while compounds 4 and 5 are non-photochromic. Finally, the possible chromic mechanisms and influencing factors for the title compounds were also discussed.

Halogen-dependent photoinduced electron transfer and chromism of three protonated nicotinohydrazide halozincates.

Three isostructural halozincates, [HNH][ZnX4]·H2O (HNH2+ = protonated nicotinohydrazide, X = I (1), Br (2), Cl (3)), have been synthesized and exhibit halogen-dependent photoinduced electron transfer and chromic properties. Due to the different electron-donating nature of halogen atoms, only iodozincate hybrid 1 can easily undergo photoinduced electron transfer and eye-detectable photochromic behavior, revealing a unique matching rule between a moderate electron acceptor and halozincates.

Stoichiometry-controlled structural and functional variation in two photochromic iodoargentates with a fast and wide range response.

By using 1-methyl-4-(carbomethoxy)pyridinium (MCMP+) as counterions, two iodoargentate hybrids, 1D [MCMP][AgI2] (1) and 3D [MCMP][Ag3I4] (2) have been synthesized and they exhibit rare electron transfer photochromism with a fast response rate, a wide response range and a long-lived charge-separated state in iodometallate systems. Noteworthily, the marked differences in the structure and photochromic performance of 1 and 2 are largely ascribed to the different aggregating behavior of electron-deficient MCMP+ counterions (C-HO hydrogen bonded trimer in 1 and π-π/C-Hπ chain in 2).

Bipyridyltriazolium Chlorobismuthate with Thermo-/Photochromic and Photoluminescent Switching Behaviors Based on ET and CT†.

Matched with 3,5-bis(pyridine-2-yl)-1,2,4-triazole (2-bpt), a new electron donor-acceptor-based chlorobismuthate(III) hybrid, [2-bpt]2[Bi2Cl10(H2O)]·5H2O was prepared solvothermally and characterized. The title compound (hydrated form) and its dehydrated form exhibit photo- and thermo-induced intermolecular electron transfer (ET), which correspond to dual ET photo/thermochromism for hydrated form, charge transfer thermochromism during dehydration, and simultaneously photoluminescent responses, respectively.

Ultrasensitive Photochromic Iodocuprate(I) Hybrid.

By employing in situ methylnicotinohydrazide dication (MNH(2+)) as an electron acceptor, we have constructed an iodocuprate(I) hybrid {[MNH][Cu2I3]2}n (1), which exhibits charge transfer (CT) thermochromism due to the intense absorption of CT and electron transfer (ET) photochromism with high photocoloration contrast and fast response to UV irradiation due to the synergetic effect of valence change of copper ions.

Hydrogen bonds and steric effects induced structural modulation of three layered iodoplumbate hybrids from nonperovskite to perovskite structure.

Directed by diprotonated organic diamines containing both primary and tertiary ammonium groups, three layered iodoplumbate hybrids, {[H2DMPDA][PbI4]}n (1), {[H2DEPDA]4[Pb5I18]}n (2) and {[H2TMEDA][Pb3I8]}n (3) (DMPDA = N,N-dimethyl-1,3-propanediamine, DEPDA = N,N-diethyl-1,3-propanediamine, TMEDA = N,N,N',N'-tetramethylethylenediamine), have been synthesized solvothermally. 1 presents a layered perovskite structure based on corner-sharing PbI6 octahedra, compound 2 consists of a Pb4I20 perovskite motif and a Pb2I10 dimeric motif and compound 3 comprises Pb3I13 units connected by face-sharing and edge-sharing modes. Structural modulations from nonperovskite to perovskite structure are strongly correlated to steric effects and hydrogen bonding interaction at the organic-inorganic interface. Band gaps for 1-3 , estimated as 2.21, 2.58 and 2.73 eV, respectively, also reveal an interesting correlation with structural modulation, and the red shift for 1 is attributed to large Pb-I(equatorial)-Pb bond angles.