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2,2'-(Pyridyl)benzimidazole is used as a probe to explore proton transfer through nafion membranes. The probe marks the availability of water in native as well as cation-exchanged membrane. Using steady state and time-resolved fluorescence studies, it has been shown that the rotation of the pyridyl and benzimidazole rings with respect to each other, which is ultrafast in higher water contents, is hindered as the water content in the membranes is decreased. In cation-exchanged membranes, it is observed that the formation of the ESPT (excited state proton transfer) state is reduced to a large extent. Thus, it may be inferred that the proton transport is observed to be hindered even in molecular dimensions of one water molecule thereby bolstering the contention that it may not be essential for water channels to break for proton conductivity to decrease.

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Tuning the photocatalytic property of zinc oxide (ZnO) nanoparticles (NPs) is timely. Dependence of photocatalysis upon size, morphology and effective surface area of the particles used has led to optimization in various synthesis procedures. The current article addresses to dictate a cost-effective, bio-friendly, modified ease-process for this issue. The synthesis of ZnO NPs with differing photophysical properties, sizes and morphologies, in order to tune its photocatalytic activity, have been extensively studied. Polyethylene glycol as the structure directing agent and different synthesis strategies were adopted. Spectroscopic and microscopic characterization techniques were employed to understand the nature of the as-synthesized samples. Photocatalytic property and photostability of the samples were determined based on experiments performed with common xanthene and azo dyes. Based on analysing the results, certain characteristics, such as smaller particle size, less agglomerated structure, higher surface area and superior lifetime of the photogenerated electrons and holes upon light illumination, were essential for ZnO NPs to act as an efficient photocatalyst.

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