Engineering Ba2 Bi2 O6 Double Perovskite with La3+ for High Current Density Visible Light Photoelectrochemical Hydrogen Evolution.

A Lanthanum ion (La3+ ) incorporation strategy is implemented to modify Ba2 Bi2 O6 -based double perovskite photoelectrodes. X-ray diffraction (XRD) characterization shows that highly crystalline Ba2 La0.4 Bi1.6 O6 double perovskites with the space group I2/m are successfully prepared. UV-vis absorption spectra and the Tauc-plot reveal an optical band gap Eg ≈1.57 ± 0.01 eV. A thickness dependence of the photoelectrodes photoelectrochemical (PEC) performance shows that the submicron (≈1 µm) 4-times spin-coated thin film photoelectrode displays strong p-type conductivity, which delivers an encouraging photocurrent density of 0.88 mA cm-2 at 0.25 VRHE under AM 1.5G illumination. 10-times coated and 20-times coated medium thick (125.8-197 µm) photoelectrodes that exhibit moderate p-type conductivity, show further enhanced photocurrent densities of 1.5 mA cm-2 at 0 VRHE . In contrast, charge recombination centers existing in a standard thick pellet (≈500 µm) Ba2 La0.4 Bi1.6 O6 photoelectrode can quench photo-generated charge carriers and greatly undermine PEC activities. The approach to doping at the Bi(III) sites contrasts with earlier efforts that focus on doping at the Bi(V) sites and thus paves the way for further tailoring a family of novel promising photocathode materials for efficient solar-water conversion devices.

Efficient, stable, tunable, and easy to synthesize, handle and recycle luminescent materials: [H2NMe2]3[Ln(III)(2,6-dipicolinolate)3] (Ln = Eu, Tb, or its solid solutions).

Three compounds with the general formulae [H(2)N(Me)(2)](3)[Ln(2,6-dpa)(3)] were prepared from cheap and readily available reactants. Microcrystalline compounds could be isolated in high yields (>80%) by a simple filtration, after only one hour reaction time in refluxing DMF. The Eu and Tb compounds have been structurally characterized by single crystal X-ray diffraction. The compounds have unusual high-absorption coefficients (>95%) and quantum efficiencies (approximately 70%). Furthermore, they are thermally stable up to 250 degrees C and appear to be UV and water tolerant. The emission colour of the final compound can be easily fine-tuned, by varying the Eu:Tb ratio during the preparation.

3-D lanthanide metal-organic frameworks: structure, photoluminescence, and magnetism.

A series of isostructural three-dimensional metal-organic frameworks [Pr(2)(N-BDC)(3)(dmf)(4)](infinity) (1), {[Eu(2)(N-BDC)(3)(dmf)(4)] x 2DMF}(infinity) (2 x 2DMF), [Gd(2)(N-BDC)(3)(dmf)(4)](infinity) (3), {[Tb(2)(N-BDC)(3)(dmf)(4)] x 2DMF}(infinity) (4 x 2DMF), {[Dy(2)(N-BDC)(3)(dmf)(4)] x 2DMF}(infinity) (5 x 2DMF) (N-H(2)BDC = 2-amino-1,4-benzenedicarboxylic acid; DMF = N,N'-dimethylformamide) with cubic 4(12) x 6(3) topology have been synthesized using solvothermal conditions. The networks were generated via formation of a dinuclear Ln(2) secondary building block, involving the dicarboxylate ligand as a bridge. The luminescent properties of the Tb(III) and Eu(III) complexes were studied and showed characteristic emissions at room temperature. Antiferromagnetic interactions between Ln(III) ions were observed from magnetic susceptibility data.

Efficient near-UV photosensitization of the Tb(III) green luminescence by use of 2-hydroxyisophthalate ligands.

The first examples of lanthanide complexes with a 2-hydroxyisophthalate ligand are reported; the blue-emitting ligand acts as a very efficient sensitizer of the Tb(III) green emissions and does so in the near-UV region.