Research

FMED, SRMIST mainly focuses on the development of functional materials for energy and environmental monitoring application which can directly impact social problems. In the current scenario, the major crisis is the environmental pollution, insufficient supply of energy to the developed automobiles and smart technologies due to the extinct use of non-renewable energy resources. The significance of “zero carbon” and “net zero greenhouse gas emission” have accelerated the research community towards the development of energy conversion, storage by means of renewable energy sources and sensors for real time monitoring of toxic gases. Our primary research is centered around advancing functional materials for various applications, including thermoelectric systems, solar cells, hydrogen generation, and gas sensing, spanning from the nano to micro scale.

Research Focus

Sustainable energy and environment

Thermoelectrics materials – waste heat recovery

Environmental monitoring – toxic gas detection

Dye sensitized solar cell

Hydrogen production

Thermoelectrics materials – waste heat recovery

In the global energy economy, only 30% of primary energy is transformed into useful energy sources while the remaining 70% is being wasted in the different industrial, transportation, residential energy conversion and power generation process. Given the urgent need to switch to carbon free energy and to palliate the harmful consequence of climatic change, the waste of energy on this scale cannot be endured. Thermoelectricity, a potential green energy technology based on Seebeck effect (i.e., waste heat to electricity conversion) offers a sustainable solution. Our fundamental research is mainly devoted to the development of thermoelectric materials such as topological insulators, transition metal dichalcogenides (TMDCs), layered chalcogenides, zintl alloys, silicide based alloys, perovskite oxides and polymers for room to mid-temperature applications.

With evolution of Internet of Things (IoT), the real-time data monitoring has become very convenient using variety of wearable electronic sensors. Batteries provided with high energy density are the only source of power used for these IoT based wearable devices. Nonetheless, the need for recharge and replacement of batteries over a period of time has urged the research for auxiliary renewable power sources. Wearable Thermoelectric generators are one the most promising source of energy due to their ability to convert low grade heat into consumable electricity. They are comprised of no moving parts leading to ultra-high life-time and are not dependent on physical motion or external climatic conditions. In our laboratory, we have been working on materials for textile based wearable thermoelectric generators for near-room temperature energy conversion. Solving the difficulties associated with the conventional flexible thermoelectric modules like scarcity and toxicity of the material, rigidity and bulky nature of the device, and complex manufacturing procedures are our prime area of research. In our research we have excluded the highly toxic Tellurium based materials and low stable polymer-based materials by replacing it with several inorganic materials like MoS2, Ag2Se, Ag2S and so on. Considering the large-scale production for real time applications, we have opted in-situ hydrothermal growth of the TE material on the conductive fabrics over the complex coating techniques. This binder-free growth technique aids the material with facile charge transport and paves a path to fabricate a highly flexible textile-based TEGs.

Dye sensitized solar cell

The solar cell division of FMED laboratory actively involves in constructing dye sensitized solar cells (DSSCs) especially for indoor applications. Precisely speaking, our team is interested in developing (i) photo-anodes for efficiently collecting the charge carriers from dye molecules and also on (ii) counter electrodes (CEs) to quickly regenerate the dye molecules through redox reaction.

Photoanodes

Photoanodes plays a critical role on the performance of DSSCs as it collects the charge carriers from dye molecules and inject to CEs. Typically, a semiconducting layer coated on a transparent conducting substrate will be used as photoanodes. Such semiconducting materials should have high electron mobility, excellent transparency and suitable energy level alignment with HOMO level of dye molecules. Indeed, we examine the performance of DSSCs based on photoanodes made of metal oxides like TiO2, SnO2, Nb2O5, NiO and perovskite structured compounds including BaSnO3.

Counter Electrodes

On the other hand, the CEs is responsible for the continuous functioning of the device in such a way, that it (i) collects the photo-generated electron from the dye molecules (which constitute electric current) and (ii) reduce the iodide electrolyte to tri-iodide ions inorder to regenerate the dye molecules. Hence, an ideal CE must possess high electrical conductivity and excellent electrocatalytic activity. Though conventional platinum CE satisfies these requirements, its high scarcity and chemical instability against 𝐼3−/𝐼− redox couple would limit the commercialization of DSSCs. Hence, we have focused to develop alternative cost effective CE based on transition metal dichalcogenides (MoS2, SnS2) and used metal organic frameworks as a self sacrificing template to prepare nitrogen doped carbon in the ensemble of 3D Ni-Co network. Further, we follow strategies like heterojunction formation between ternary compounds like CuCo2O4, ZnCo2O4, NiCo2O4 for CEs.

Gas sensors

The rapid urbanization and the release of harmful gases from industries and automobiles have resulted in many health issues. Among the hazardous pollutants present in industrial and automobile exhaust, Nitrogen dioxide (NO2) is a particularly hazardous one, causing airway inflammation, bronchoconstriction, and reduced lung function in children. These effects can lead to the onset of asthma attacks in children at an early age. The fact that NO2 is colorless and odorless at lower temperatures and room temperature makes it undetectable by human senses. Therefore, developing high-performance sensors to accurately and rapidly detect NO2 gas at room temperature is essentially important to protect human health and environment. In this regard, we are constructing room temperature NO2 gas sensor based on Metal oxide Semiconductor (MOS) and Transition Metal Dichalcogenides (TMDs) via wet chemical and physical techniques. To improve the sensing performance, we are using various strategies such as making heterostructures, doping with different metals, noble metal decoration, composite with carbon-based materials and liquid exfoliation.

Hydrogen production

The hydrogen (H2) gas production is decisive approach to satisfy the overall global energy demand and resolve the environmental hazards caused by surplus fossil fuels. It has 3-4 fold higher mass energy density than other existing gasoline which is directly promote as hydrogen fuel through directly combustion route without emission of greenhouse gases as by product. In current scenario, (photo)electrocatalysts are received major contribution to green and clean route to production of H2 gas production via water splitting process. Here, we focus to identification of low-dimensional semiconductors/ earth abundant metal nanostructure (1D/2D) as an efficient (photo)electrocatalysts for the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) is prime goal to the development of (photo)electrochemical cell for overall water-splitting process. Moreover, we also highlight our research on design and fabrication of (photo)electrocatalysts such as silicon, transition metal dichalcogenides, bimetallic sulfide, metal organic framework (MOF) and so on.

Photodetector

2D topological insulators (TIs), and TMDs semiconductors are highly suitable forlight detection applications. Their synergistic behaviour combines photon absorption in the broad band regime of the electromagnetic spectrum with virtuous photocurrent generation, photosensitivity and short rise/decay time. Since several 2D materials can be dispersed in organic solvents, thin films can be effortlessly designed by means of a solution process without the essential for high-cost equipment. This makes them specifically attractive for large area applications. The low processing temperature (<150°C), makes the option to use a wide range of substrates. Our group intended to fabricate the solution processed near- infrared photodetectors. These photodiodes can detect near-infrared light are interesting for a range of applications as it enables night vision, health monitoring, optical communications and three-dimensional object recognition. Near-infrared photodetectors depend on low-band gap materials, but consequently low carrier injection barrier and enhanced dark current (ID) generation in the bulk or at interfaces results in much higher ID. Hence, we intend to investigate heterojunction photodiodes response up to 1200 nm with various design of devices architecture and novel absorber layers.