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Metal organic frameworks (MOFs) or Metal coordination polymers (CPs) with controlled structure on the micro/nano-scale have attracted intense interest for potential applications in a wide variety of fields, such as energy storage and conversion, chemical and biological sensing, and catalysis. Here, we report a new class of photocatalytic material, Ag(I) based nano-micro structured coordination polymer (Ag(I)-CP), which offer performance at a level competitive with known semiconductors in photocatalytic water oxidation and oxidation of organic compounds, such as dye/ organic pollutants present in contaminated water. The coordination polymer was synthesized by a wet-chemical route and has been characterized using powder X-ray diffraction, X-ray photoelectron spectroscopy and electron microscopy. The 2 Ag(I)-CP has notable semiconducting characteristics and charge transfer ability due to ligand centered charge transfer (LCCT) in combination with metal to ligand charge transfer MLCT (Ag-O cluster to ligand centre) as established from experimental absorption, luminescence and photoelectrochemical measurements alongside DFT calculations. Notably, Ag(I)-CP exhibits a highly reactive valance band potential +3.40 V vs NHE, composed of hybridized state of O 2p and C 2p through the organic linker and Ag 4d, this acts as an active center for the generation of reactive oxygen species (ROS) i.e., hydroxyl radical and h + under photocatalytic conditions. Consequently, the photogenerated species facilitate effective oxidations of water and organic contaminants such as tartrazine, rhodamine B and 2, 4-dichlorophenol under UV light irradiation. Furthermore, our results suggest that the Ag(I)-CP could be used as a promising material for the development of heterostructure for variety of photo-assisted-redox catalysis.

The optical properties of bare and passivated Zn n Se n ͑n =1-13͒ clusters have been studied within the framework of time-dependent local density approximation. The atomic structure of the clusters has been obtained using projector augmented wave pseudopotential method, with generalized gradient approximation for the exchange-correlation energy. The small clusters with n up to 5 have two-dimensional ͑2D͒ structure and for larger sizes, cagelike 3D structures become favorable. At n = 13, the clusters start getting an atom inside the cage to attain bulklike local structure. For the bare clusters, the highest occupied molecular orbital ͑HOMO͒ and lowest unoccupied molecular orbital ͑LUMO͒ gap increases from a small value for ZnSe dimer and beyond n = 3, the variation is small. On the other hand, the HOMO-LUMO gap of the clusters passivated with partially charged hydrogen atom decreases nearly monotonically with increasing size, though the value remains higher compared with that of the bare clusters even for the case of n = 13. Further, the optical absorption spectra and the corresponding optical gap have been calculated and a decreasing trend as a function of the increasing cluster size has been obtained. This compares well with the experimental results available on larger clusters in the literature though the calculated values underestimate the optical absorption gap as expected within the local density approximation framework.

ARTICLES YOU MAY BE INTERESTED INA computational ab initio study of surface diffusion of sulfur on the CdTe (111) CdTe is one of the most promising semiconductor for thin-film based solar cells. Here we report a computational study of Cd and Te adatom diffusion on the CdTe (111) A-type (Cd terminated) and B-type (Te terminated) surfaces and their migration paths. The atomic and electronic structure calculations are performed under the DFT formalism and climbing Nudge Elastic Band (cNEB) method has been applied to evaluate the potential barrier of the Te and Cd diffusion. In general the minimum energy site on the surface is labeled as A a site. In case of Te and Cd on B-type surface, the sub-surface site (a site just below the top surface) is very close in energy to the A site. This is responsible for the subsurface accumulation of adatoms and therefore, expected to influence the defect formation during growth. The diffusion process of adatoms is considered from A a (occupied) to A a (empty) site at the nearest distance. We have explored three possible migration paths for the adatom diffusion. The adatom surface interaction is highly dependent on the type of the surface. Typically, Te interaction with both type (5.2 eV for A-type and 3.8 eV for B-type) is stronger than Cd interactions(2.4 eV for B-type and 0.39 eV for A-type). Cd interaction with the A-type surface is very weak. The distinct behavior of the A-type and B-type surfaces perceived in our study explain the need of maintaining the A-type surface during growth for smooth and stoichiometric growth. C