Gaining a deeper understanding of enzyme catalysis is of great practical and fundamental importance. Over the years it has become clear that despite advances made in experimental mutational studies, a quantitative understanding of enzyme catalysis will not be possible without the use of computer modeling approaches. While we believe that electrostatic preorganization is by far the most important catalytic factor, convincing the wider scientific community of this may require the demonstration of effective rational enzyme design. Here we make the point that the main current advances in enzyme design are basically advances in directed evolution and that computer aided enzyme design must involve approaches that can reproduce catalysis in well-defined test cases. Such an approach is provided by the empirical valence bond method.

First use of a surfactant-free SnS nanorods synthesized by a solvothermal method in supercapacitor applications having high specific capacitance.

We report the studies on composite gel polymer electrolytes (GPEs) comprising 0.5 M solution of sodium trifluoromethane sulfonate (Na-triflate or NaTf) in ionic liquid 1-ethyl 3-methyl imidazolium trifluoromethane sulfonate (EMITf) entrapped in poly (vinylidinefluoride-cohexafluoropropylene) (PVdF-HFP) dispersed with passive filler Al 2 O 3 and active filler NaAlO 2 particles. The freestanding films of the composite GPEs, prepared from solution-cast method, offer optimum ionic conductivity at room temperature (6.3-6.8 × 10 − 3 S cm − 1 and 5.5-6.5 × 10 −3 S cm −1 for Al 2 O 3 -and NaAlO 2 -dispersed GPEs, respectively), with sufficient electrochemical stability and excellent thermal stability up to 340°C. As observed from XRD and SEM, the composites are of predominantly amorphous and porous character, which support the high ionic conduction. The sodium ion transport number has been found to be ∼0.27 for Al 2 O 3 -dispersed GPE and 0.42 for NaAlO 2 -dispersed GPE, which indicates the predominant role of passive and active fillers, Al 2 O 3 and NaAlO 2 , respectively. The dispersion of NaAlO 2 enhances the sodium ion conductivity in composite GPE substantially. The overall ionic conductivity is same as in the case of Al 2 O 3 dispersion. The performance characteristics of GPE, particularly, dispersed with active filler NaAlO 2 show its potential applicability as electrolyte/ separator in sodium batteries.

The development of low cost supercapacitor cells with unique capacitive properties is essential for many domestic and industrial purposes. Here we report the first ever application of SnS-reduced graphene oxide (SnS/RGO) layered nanocomposite as a superior electrode material for symmetric aqueous hybrid supercapacitors. We synthesized SnS/RGO nanocomposite comprised of nanosheets of SnS and graphene oxide via a one-pot hydrothermal approach. in situ as-synthesized SnS/RGO is devised for the first time to give high specific capacitance 500 Fg, energy density 16.67 Wh kg and power density 488 W kg. The cell retains 95% charge/discharge cycle stability up to 1000 cycles. In-short, the SnS/RGO nanosheet composite presented is a novel and advanced material for application in high stability moderate value hybrid supercapacitors. All the currently available surveys in literature state the potential applicability of SnS as the anode material for reversible lithium/sodium ion batteries (LIBs/NIBs) but there is a lack of equivalent studies on electrochemical capacitors. We filled up this knowledge gap by the use of the same material in a cost-effective, highly active hybrid supercapacitor application by utilizing its pseudocapacitance property combined with the layered capacitance property of graphene sheets.

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We report titania nanoheterostructures decorated with silver, exhibiting tuneable photochromic properties for the first time when stimulated only by visible white light (domestic indoor lamp), with no UV wavelengths. Photochromic materials show reversible color changes under light exposure. However, all inorganic photochromic nanoparticles (NPs) require UV light to operate. Conventionally, multicolor photochromism in Ag-TiO films involves a change in color to brownish-gray during UV-light irradiation (i.e., reduction of Ag to Ag) and a (re)bleaching (i.e., (re)oxidation of Ag to colorless Ag) upon visible-light exposure. In this work, on the contrary, we demonstrate visible-light-induced photochromism (ranging from yellow to violet) of 1-10 mol % Ag-modified titania NPs using both spectroscopic and colorimetric CIEL*a*b* analyses. This is not a bleaching of the UV-induced color but a change in color itself under exposure to visible light, and it is shown to be a completely different mechanism-driven by the interfacial charge transfer of an electron from the valence band of TiO to that of the AgO clusters that surround the titania-to the usual UV-triggered photochromism reported in titania-based materials. The quantity of Ag or irradiation time dictated the magnitude and degree of tuneability of the color change, from pale yellow to dark blue, with a rapid change visible only after a few seconds, and the intensity and red shift of surface plasmon resonance induced under visible light also increased. This effect was reversible after annealing in the dark at 100 °C/15 min. Photocatalytic activity under visible light was also assessed against the abatement of nitrogen oxide pollutants, for interior use, therefore showing the coexistence of photochromism and photocatalysis-both triggered by the same wavelength-in the same material, making it a multifunctional material. Moreover, we also demonstrate and explain why X-ray photoelectron spectroscopy is an unreliable technique with such materials.

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