Siderophore mediated mineralization of struvite: A novel greener route of sustainable phosphate management.

Efficient and sustainable removal of phosphate ions from an aqueous solution is of great challenge. Herein we demonstrated a greener route for phosphate recovery through struvite formation by using bacterial siderophore. This method was efficient for removal of phosphate as low as 1.3 mM with 99% recovery efficiency. The siderophore produced by Pseudomonas taiwanensis R-12-2 act as template for the nucleation of struvite crystals and was found sustainable for recycling the phosphorous efficiently after twenty cycles. The formation of struvite crystals is driven by surrounding pH (9.0) and presence of Mg2+ and NH4+ ions along with PO43- and siderophore which was further validated by computational studies. The morphology of struvite was characterized by scanning electron microscopy, followed by elemental analysis. Furthermore, our results revealed that the siderophore plays an important role in struvite biomineralization. We have successfully demonstrated the phosphate sequestration by using industrial waste samples, as possible application for environmental sustainability and phosphate conservation. For the first time electrochemical super-capacitance performance of the struvite was studied. The specific capacitance value for the struvite was found to be 320 F g-1 at 1.87 A g-1 and retained 92 % capacitance after 250 cycles. The study revealed the potential implications of siderophore for the phosphate recycling and the new mechanism for biomineralization by sequestering into struvite.

Metal Coordination Polymer Framework Governed by Heat of Hydration for Noninvasive Differentiation of Alkali Metal Series.

We illustrate that the extent of hydration and consequently the heat of hydration of alkali metal ions can be utilized to control their insertion/deinsertion chemistry in a redox active metal coordination polymer framework (CPF) electrode. The formal redox potential of CPF electrode for cation intercalation is inversely correlated to hydrated ionic radii, with clear distinction between the intercalation of ions across alkali metal series. This leads to noninvasive identification and differentiation of cations in the alkali metal series by utilizing a single sensing platform.

Coupling Energy Capture and Storage - Endeavoring to make a solar battery.

Storage of solar radiation is currently accomplished by coupling two separate devices, one that captures and converts the energy into an electrical impulse (a photovoltaic cell) and another that stores this electrical output (a battery or a supercapacitor electrochemical cell). This configuration however has several challenges that stem from a complex coupled-device architecture and multiple interfaces through which charge transfer has to occur. As such presented here is a scheme whereby solar energy capture and storage have been coupled using a single bi-functional material. Two electroactive semiconductors BiVO4 (n-type) and Co3O4 (p-type) have been separately evaluated for their energy storage capability in the presence and absence of visible radiation. Each of these have the capability to function as a light harvester and also they have faradaic capability. An unprecedented aspect has been observed in that upon photo-illumination of either of these semiconductors, in situ charge carriers being generated play a pivotal role in perturbing the electroactivity of the redox species such that the majority charge carriers, viz. electrons in BiVO4 and holes in Co3O4, influence the redox response in a disproportionate manner. More importantly, there is an enhancement of ca. 30% in the discharge capacity of BiVO4 in the presence of light and this directly provides a unique route to augment charge storage during illumination.

Nanostructured MoS2/BiVO4 Composites for Energy Storage Applications.

We report the optimized synthesis and electrochemical characterization of a composite of few-layered nanostructured MoS2 along with an electroactive metal oxide BiVO4. In comparison to pristine BiVO4, and a composite of graphene/BiVO4, the MoS2/BiVO4 nanocomposite provides impressive values of charge storage with longer discharge times and improved cycling stability. Specific capacitance values of 610 Fg-1 (170 mAhg-1) at 1 Ag-1 and 166 Fg-1 (46 mAhg-1) at 10 Ag-1 were obtained for just 2.5 wt% MoS2 loaded BiVO4. The results suggest that the explicitly synthesized small lateral-dimensioned MoS2 particles provide a notable capacitive component that helps augment the specific capacitance. We discuss the optimized synthesis of monoclinic BiVO4, and few-layered nanostructured MoS2. We report the discharge capacities and cycling performance of the MoS2/BiVO4 nanocomposite using an aqueous electrolyte. The data obtained shows the MoS2/BiVO4 nanocomposite to be a promising candidate for supercapacitor energy storage applications.