Enhancement of photoconversion efficiency of ZnO nanorod-based dye-sensitized solar cells in presence of ZrO2 thin energy barrier.

In order to enhance the power conversion efficiency of ZnO nanorods-based dye-sensitized solar cells (DSSCs), ZrO2 thin energy barriers were formed on ZnO nanorods using a sol-gel method. In DSSCs, the short-circuit current was substantially increased, and the dark current was significantly reduced in the presence of the ZrO2 layer. Due to suppressed recombination in the presence of the ZrO2 layer, 81.3% increment of power conversion efficiency is achieved compared to those without ZrO2 layer.

Modification of ion permeability utilizing pH-dependent selective swelling of polyelectrolyte multilayer films.

The selective swelling behavior of polyelectrolyte multilayer (PEM) films prepared by layer-by-layer (L-b-L) assembly influences the ion-permeability in contrast to surface charge density of the films. The cation terminated polyethylene amine (PEI) and anion terminated polyacrylic acid (PAA) were dissolved in DI water, and the pH was adjusted to 10 and 4, respectively, exemplifies thick denser film with good layering structure. The layered polyelectrolyte films has selective swelling behavior at pH 4 (PEI) or pH 10 (PAA), influences the permeability of both Ru(NH3)6(2+) and Fe(CN)6(3-) rather than surface charge character or film charge density. The swollen top most layer shows "on" character, whereas, shrunken top most layer shows "off" character for the ion-permeability. Such "on-off" character can be used for the pH-dependent switches based on surface morphology.

Efficient hydrogen sorption in 8-connected MOFs based on trinuclear pinwheel motifs.

Two new metal-organic frameworks based on trinuclear pinwheel motifs are prepared using dicarboxylate and diamine ligands. The structure of [Co3(bdc)3(dabco)] (1) (bdc = 1,4-benzenedicarboxylate; dabco = 1,4-diazabicyclo[2.2.2]octane) is described as pillared layers, whereas [Co3(ndc)3(dabco)] (2) (ndc = 2,6-naphthalenedicarboxylate) forms a variation of primitive cubic net with 3D connected pores. The two 8-connected MOFs are thermally stable at 160 and 250 degrees C for 1 and 2 respectively in the air and possess corrugated channels owing to the high connectivities of the secondary building unit. As a result, they show highly efficient hydrogen sorption capabilities. Especially, a high hydrogen uptake (2.45 wt % at 77 K and 1 bar) is observed for 2 that has the unique combination of high surface area and small portals.