Indian Association for the Cultivation of Science

About: Indian Association for the Cultivation of Science is a education organization based out in Kolkata, India. It is known for research contribution in the topics: Catalysis & Excited state. The organization has 3867 authors who have published 10457 publications receiving 220098 citations.

Gold nanoparticles: microbial synthesis and application in water hygiene management.

Abstract: A green chemical method to synthesize nanogold-bioconjugate and its eco-friendly promising role to purify contaminated waters has been described. Gold nanoparticles of 10 nm average diameter are produced on the surface of Rhizopus oryzae, a fungal strain, by in situ reduction of chloroauric acid (HAuCl4). The nanogold-bioconjugate (NGBC) showed strong adsorption capacity toward different organophosphorous pesticides. The EDXA study confirms adsorption of pesticides on the conjugate material surface. Morphological changes of the NGBC material after adsorption of organophosphorous pesticides were detected by atomic force micrographs. NGBC shows high antimicrobial activity against several Gram-negative and Gram-positive pathogenic bacteria as well as the yeasts Saccharomyces cerevisiae and Candida albicans. The treatment of microbial cells with NGBC caused rupture of cell membrane as revealed in scanning electron and fluorescence micrographs. These unique characteristics of NGBC have been successfully utiliz...

Doping Cu in semiconductor nanocrystals: some old and some new physical insights.

Abstract: Cu-doped inorganic semiconductors with concomitant optical properties have garnered enormous research interest in the last two decades. However, uncertainties over the origin of Cu emission, its oxidation state, resemblance with trap state emission, position of Cu d-state, emission spectral width, and moreover understanding of the doping mechanism restricted the wide development of the synthetic methodology for high-quality Cu-doped nanocrystals. It has been shown recently that the emission from Cu-doped semiconductor nanocrystals can span over a wide spectral window and could be a potential color tunable dispersed nanocrystal emitter. Herein, we report the size and composition of variable Cu-doped ZnS/Zn1−xCdxS zinc-blende (ZB) surface alloyed nanocrystals with intense, stable, and tunable emission covering the blue to red end of the visible spectrum. Further, the Cu dopant emission is distinguished from trap state emission, and the composition variable spectral broadening has been justified on the accou...

Transport properties of vanadium germanate glassy semiconductors.

Abstract: Measurements are reported for the dc as well as frequency-dependent (ac) conductivities (real and imaginary parts) for various compositions of the vanadium germanate glassy semiconductors in the temperature range 80--450 K. The experimental results are analyzed with reference to various theoretical models proposed for electrical conduction in amorphous semiconductors. The analysis shows that at high temperatures the temperature dependence of the dc conductivity is consistent with Mott's model of phonon-assisted polaronic hopping conduction in the adiabatic approximation, while the variable-range-hopping mechanism dominates at lower temperatures. Schnakenberg's model predicts the temperature dependence of the observed activation energy in the intermediate temperature range. The temperature dependence of the ac conductivity is consistent with the simple quantum-mechanical tunneling model at lower temperatures, although this model cannot predict the observed temperature dependence of the frequency exponent. The overlapping-large-polaron tunneling model can explain the temperature dependence of the frequency exponent at low temperature; however, this model predicts a temperature dependence of the ac conductivity much higher than the observed data show. On the other hand, the correlated-barrier-hopping model is consistent with the temperature dependence of both the ac conductivity and its frequency exponent over the entire temperature range of measurements.

Developments of Metal Phosphides as Efficient OER Precatalysts.

Abstract: Over the last 2 years, it has been observed that metal phosphides have emerged as efficient electrocatalysts for both hydrogen and oxygen evolution reactions (HER and OER). However, while the HER has been immensely studied, the OER is limited. The chemistry in the OER is more complicated and involves irreversible surface oxidations of these materials and transforms them to their corresponding oxide/oxyhydroxide. Interestingly, these in situ changes have been widely observed generating more active catalysts with superior performance. Phosphides of Fe, Co, and Ni with different compositions have been proved as efficient catalysts for water oxidation. Considering their importance, structures, compositions, surface modifications, and also in situ transformation during electrolysis, this Perspective provides state-of-the-art views of their current developments and future prospects.