There are a variety of projects currently being undertaken in our lab. 

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Harnessing solar energy (by either storing or converting it effectively) has become a pivotal requirement in the pursuit of environmentally benign technologies. We aim to tackle this use by the judicious use of photoactive inorganic/hybrid structures. As such, the emphasis in our lab (especially over the last 4 to 5 years) has been to use synthetic inorganic chemistry as a tool to form intricate structures that are then exploited in applications predominantly associated with solar energy capture and conversion. Three directions that have principally been pursued in the last few years are (a) formation of components in either energy conversion devices (photovoltaics) or energy storage devices (i.e. batteries, hybrid-capacitors), (b) formation of photo-catalysts or electro-catalysts for either pollution remediation or water splitting based reactions and (c) also as a tangential application, formation of viable biocompatible nanostructures for enhanced drug delivery. We therefore aim to contribute to the conceptual understanding of how chemical stoichiometry along with the architecture of inorganic materials can be exploited in these aforementioned applications. 

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• Components in solar cells (dye sensitized; hybrid perovskite based cells)

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The organic-inorganic hybrid perovskite materials, especially methyl ammonium lead iodide (MAPI), have garnered a huge interest of the photovoltaic community due to their insurmountable charge carrier properties. The rapid surge of the photon to current conversion efficiencies (PCE) with MAP as a light absorber, in a span of 9 years showed promise to bring a breakthrough in the photovoltaic technologies, due to the ease of manufacture and the low cost of fabrication, until the literature started highlighting the instability of this material. The degradation of this material stems from its limited tolerance to moisture, oxygen and light. Other than the inherent propensity of this material to degrade under ambient conditions, we have been able to demonstrate the role of substrate in dictating the rate and product of degradation, and also devised a simple, chemical route to regenerate the degraded perovskite. Additionally, in an attempt to fabricate stable and robust solar cells, we have synthesized a novel hybrid compound, imidazolium lead iodide (ImPI) which has the same stoichiometry ABX3 as the perovskite, but crystallographically is a hexagonal structure. We have shown, based on the structural analysis and our experiments, that ImPI is much more stable to ambient conditions as compared to the conventional perovskite MAP and has the potential to serve as a promising candidate for photovoltaic devices. Work in this area is ongoing....

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• As components in energy storage devices - faradaic materials for batteries or capacitive MX2ene's for supercapacitors

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To meet the challenge of discontinuity of the renewable energy flow, development of effective energy storage systems with high energy and high power density is necessary. We have pioneered the use of a new electroactive material i.e. BiVO4 where faradaic behavior of Bi ion is recorded. In the constant search for a better energy storage material it’s an attempt to move beyond the conventional Lithium and Sodium based battery materials. BiVO4 is an n-type semiconductor which has shown excellent electrochemical behavior with specific capacitance of ca.1200 Fg-1 at 1 Ag-1. BiVO4 in conjunction with SWCNTs has shown improved electrochemical performance and impressive cycling stability. To further improve its performance, BiVO4 is combined with a few-layered nanostructured MoS2 and has demonstrated much larger values of charge storage, longer discharge times and improved cycling stability in comparison to pristine BiVO4, or graphene/BiVO4 composites, and hence is considered a promising candidate for energy storage. The area of merging energy capture and storage is still emerging especially in terms of evolving the conceptual idea of directly storing solar radiation as opposed to forming devices that consist of independent batteries/supercapacitors that are separately coupled with solar cells. Also, generating charge carriers that could be stored electrostatically or electrochemically, using photo assisted process is now being exploited using technologies involving DSSC (dye sensitized electron generation), photoelectrochemical or photochemical assisted production of high energy electrons and these are being interfaced with energy storage electrodes. WO3/TiO2 and Ni(OH)2/TiO2 are two of the most widely studied hybrid energy storage systems but unfortunately the devices show poor efficiencies mainly owing to multiple interfaces being involved. Therefore, we have adopted an alternate approach for coupling energy capture and storage in that the aim has been to create a strategy that minimizes interfaces and so in principle can lead to better performance and charge transport efficiency. We have studied BiVO4 redox behavior in the presence and absence of light in order to provide insight into whether it is feasible for an electroactive component to be also photoactive in a single energy storage device. Work in this area is ongoing....

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• Photo- and Electro-catalysts for pollution remediation and for H2/O2/H2O2 generation

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In terms of effectively exploiting solar energy, there are a few routes, one of which has gain a great deal of popularity and that involves catalysis. The aim is to have a route through which solar energy can be converted into viable forms of energy suitable for human consumption. The easiest way of looking at this problem is to think of it as an energy conversion problem - converting solar energy into some form of stored energy. This stored energy is very commonly thought of being stored inside chemical bonds. As such, a molecule is synthesized using the solar energy and this energy therefore is effectively converted into chemical energy yielding ‘solar fuels’. The molecule can subsequently be combusted (or participate in another chemical reaction) at a later date to release the energy. One of the main advantages of such route is that the captured energy is stored and can be used at will and perhaps at a different location from where it was captured. For this route to be viable, catalysts are needed - these are predominantly inorganic materials that can be used in heterogeneous phase, recovered, recycled and their surface and physical properties play a pivotal role. Work in out group has involved synthesis of a variety of catalysts that can be exploited either under photo and/or electrical stimulus to drive a variety of reactions.
 

• For drug delivery applications

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Drug delivery vehicles/devices are promising candidates for the delivery of pharmaceuticals and biopharmaceuticals mainly because they ideally augment aspects such as targeted delivery rate of internalization, therapeutic efficiency and perhaps also minimize toxicity effects of the loaded drug. The development and establishing the safety of novel drug vehicles is a tedious and challenging process with one of the primary challenges being that a single device should be able to encapsulate a diverse array of chemical and biological compositions. These compositions can consist of either hydrophobic, hydrophilic or amphiphilic structures and should be easily encapsulated in sufficient quantities. Moreover, the vehicles have to be adaptable so that they can sequester the aforementioned wide array of chemical compositions using, in principle, a relatively trivial methodology. The delivery devices should also have safety, patient and regulatory compliance and should also be resilient  to a variety of denaturing conditions, and it would also be beneficial that these devices should be amenable to surface functionalization so that they can be exploited for targeted delivery.
Work in our lab has focused on a material that circumvents many hurdles associated with inorganic materials that are used for drug delivery. A systematic study is ongoing efficacy of novel HAp hollow nanotubes and their behaviour is being studied in comparison to the oft-cited spherical, dense nanoparticles of HAp. Hence a novel parameter has been exploited wherein the morphology is manipulated from a spherical structure to a 1D hollow nanotubular shape for drug delivery. We are working on (A) single-particle analysis showcasing XRD, SEM, TEM, SAED, EELS, EDS and BET measurements to prove the sole formation of HAp hollow nanotubes, (B) the biocompatibility assays and internalization study of these tubes in presence of cell lines such as RN46A Neuronal cells, L929 Mouse Fibroblast cells, Primary skin cells, Hela cells and MG63 Osteoblastoma cells, (C) comparison of these two structures for encapsulation capability using molecules whose composition has been varied from being hydrophilic to hydrophobic along with varying their molecular weights upto 70kDa and (F) a comparative study of nanotubular vs. spherical morphology showcasing their loading capacity using a Paclitaxel and Doxirubicin as model cargos, the release/retention study showing improved rates for the ID structures and cell internalization using Imaging Flow Cytometry.  Most importantly, the mechanism of cellular uptake of spherical vs 1D hollow tubes is being evaluated.

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