Research

 

Fuel Cells

Hydrogen, having largest energy density over any other fuel in the world, came up as a rising star towards the replacement of diminishing fossil fuel because of not only its broad application as fuel in renewable energy sources but also the ease to produce. Thus extensive research on the development of new, inexpensive and abundant HER catalysts are highly desired.

Difficulties in storage and transport of highly flammable hydrogen gas led to increase the research efforts in the usage of small organic molecules with high volumetric energy density (such as methanol, ethanol, formic acid etc.) as a fuel. However, oxidation kinetics of the small organic molecules is slower than hydrogen. Therefore, increasing research efforts have to be carried out to design and develop more efficient anode electrocatalysts.

One of the major obstacles in the fuel cells, metal air batteries and electrolyzers is actually the development of electrode material for oxygen electrochemistry namely Oxygen Reduction Reaction-ORR (in fuel cells, batteries) and Oxygen Evolution Reaction-OER (in electrolyzers) due to their much slower reaction kinetics. Though highly monodispersed nanostructure catalysts are typically used to enhance the rate of reactions, under the real application conditions especially in acidic medium at low temperature such catalysts faces severe challenges towards the activity, stability, cost and abundant issue of the materials used. Therefore, designing and developing highly robust and low cost efficient electrocatalysts for OER and ORR is intensely desirable.

The group has already developed various robust and highly efficient catalysts such as Pd2Ge for ethanol oxidation, Pd3Pb for both formic acid and ethanol oxidation, Pt2In3 for methanol and ethanol oxidation and many other catalysts for hydrogen evolution reaction and oxygen reduction reactions.

Exploratory Synthesis

Intermetallics have found important applications in various areas such as structural materials in aircraft, superconductors in magnetic resonance imaging instruments, magnets in computer disk drives, thermoelectric materials and shape memory alloys. Intermetallic compounds are a combination of two or more metals with properties such low density, high specific yield strength (yield strength/density), high specific stiffness, good oxidation resistance and good creep resistance at high temperatures make them occupy an intermediate position between alloys and ceramics. Their crystal structure is different than their constituent elements and exhibit metallic behaviour with more localized covalent bonding.

The aim of our group is the synthesis of binary, ternary and quaternary intermetallics by exploratory metal flux method. After establishing the crystal structure using single crystal X-ray diffraction, the synthesis will be scaled up using conventional techniques like arc-melting, high frequency induction furnace and ceramic methods. The compounds will be characterized XRD, SEM/EDX, TEM, IR, UV etc. Magnetic and transport properties of these compound will be measured. The group has succeeded in the synthesis of various new compounds (Yb5Ga2Sb6, Yb2AuGe3, YbCu4Ga8, Yb7Ni4InGe12 etc.) and various new structural types. A specific focus will be given to the compounds between Ce, Eu and Yb as they are expected to exhibit mixed valency, which may lead to interesting physical properties like heavy fermion, kondo, super conductivity, zero thermal expansion etc.

Polyoxometalate based hybrid materials (bulk and nano) for applications in Energy and Catalysis

Hybrid materials synthesized at the interface of two contrasting fields have the advantage of assembling the rich properties of both in enhancing their potential in applications and if carefully designed also is devoid of the negative ones of both. Polyoxometalate based hybrids are one such class where the potential of these electron rich BrØnsted acids can be explored fully by forming hybrids with other units (like organic ligands, ionic liquids, clays, inorganic cations, nano-heterostructure, carbon support etc.) to make them more viable for practical applications. Polyoxometalates (POMs) are a class of metal-oxy anion clusters (of nano-dimensions) usually consisting of transition metals (Cr, V, Ti, Mn, Co, Ni, Fe, Cu, Mo, W, Nb) in their highest oxidation states. They possess numerous physicochemical properties which render them great potential for applications in versatile fields like catalysis, biology and energy. These properties can be enlisted as the following: (a) redox facile nature, (b) photoactive properties, (c) hydrolyzable protons giving rise to acidity, and (d) anionic and oxygen-rich nature. POMs cater to all kinds of catalysis eg. organic, electro and photo catalysis. In our lab we are interested in synthesizing different hybrid and nano systems involving polyoxometalates which can act active materials in the frontiers of energy conversion and generation. The materials are characterized through Single crystal XRD, Powder XRD, Microscopy (TEM & SEM), Spectroscopy (IR, UV, PL, Raman, Mass) and thorough extensive elemental analysis. We employ these materials both electrochemically (Hydrogen evolution reaction, Oxygen evolution reaction, water splitting) and photocatalytically (Hydrogen evolution and water splitting) as catalysts to facilitate energy conversions from renewable sources, which is currently one of the most important and highly estimated research topic around the globe. These hybrid materials are also applied for catalysis of small organic molecules to synthesize important products which act as starting materials in many industries and pharmaceutical companies. Photovoltaics is another area of application where polyoxometalate based materials have shown promises in recent past. Situated in an institute with extremely advanced world class research facilities, we at SSICL are bent upon exploring and designing many such kinds of novel systems (both bulk and nano) for targeted applications in energy and catalysis.


 

Electrochemical Supercapacitor

Recent trends toward intermittent energy sources (e.g. wind and solar), advanced mobile devices and electric vehicles are placing increased demands on energy storage platforms. Electrochemical storage devices, in particular batteries and supercapacitors are two such devices with the potential to meet the energy storage demands of the future. Batteries are high energy capacity devices which store energy through redox reactions in the bulk material of the device. Supercapacitors are high power devices which store energy in the electrochemical double layer. Electric double layer capacitors (and pseudo capacitors) form the class of supercapacitors, which are also electrochemical energy storage devices but with different characteristics than battery. While the energy density of supercapacitors are much smaller than that of battery, the power density can be orders of magnitude higher because they can be charged and discharged very fast. Carbon materials are typically used as electrodes in electric double layer capacitors whereas oxides, hydroxides, chalcogenides and other electrode materials give pseudo-capacitance. We are currently developing and characterizing the performance of new materials for high-density energy storage.

Carbon Dioxide reduction

Power production from combustion of fossil fuels releases CO2, which is mainly responsible for global warming and cause severe problems to both ecology and human beings. The rise in atmospheric CO2 levels must be slowed or reverted to avoid undesirable climate change. Materials capable of cost-effective CO2 conversion into chemicals and fuels would help in stabilizing the atmospheric levels of greenhouse gas. The potential products can be obtained with CO2 conversion are formic acid, methanol, CO and ethylene. At present there is no commercially viable process for the conversion of CO2 to useful chemicals and the current state-of-the-art materials are expensive, which limit commercial implementation. For example, although several materials are known for the electrochemical conversion of CO2, until now only precious metals such as Au and Ag could promote this process with Faradaic efficiency more than 80%. Because of the durability and poisoning effect many efficient catalysts are far beyond commercialization. We strategically focus on the synthesis of nanomaterials in various forms (metals, bimetals, alloys, intermetallic, core shell etc.) and study their efficiency in the photochemical, electrochemical and heterogeneous conversion of CO2 into fuel and chemicals. The reaction mechanism and kinteics are completely understood by a detailed electronic structure calculations. Our materials and methods are expected to have the potential to convert waste CO2 to produce gasoline, diesel fuel, jet fuel, and industrial chemicals.


 

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