Inorganic chemistry/Materials/Polymers/Catalysis/High-Energy materials

 

The research activity of our group revolves around the concept of Health, Energy, Environment, and Defense (HEED). The primary focus of the research is the design of materials aimed at addressing fundamental issues about the efficiencies of devices related to Energy Harvesting (solar energy and hydrogen production), Energy Storage (battery and capacitors), and Energy Release (propellant and explosives). For these applications, we have been involved in producing nanomaterials, small molecules, and polymer materials and their application studies.

Nano materials:

➢ Methodology development for the synthesis of metal and metal chalcogenides nanoparticles

➢ Production of organic surfactant free nanoparticles for optoelectronic and biological applications

➢ High-energy materials for spontaneous and controlled energy release

➢ Catalysis by nanoparticles (reaction catalysis and degradation catalysis)

Small molecules:

➢ Nitrogen and boron rich small molecules and salts as high-energy materials

➢ Metal complexes and their catalytic activities (Cu, Zn and Cd complexes)

➢ Synthesis of cyclic and polymeric carbonates from carbondioxide

Polymers:

➢ Polycarbonates and polyethers with intrinsic disordered framework for Li-ion mobility

➢ Solid polymer electrolytes for batteries

➢ Polymers having phosphorus

Research Highlights

Nanomaterials

The nanoparticles obtained by synthetic chemical methods are surrounded by organic surfactant molecules or polymers, known as capping or stabilizing agents. These undesired capping agents hinder the chances of harnessing the benefits of surface or size-dependent properties to their full potential. The reasons for this shortcoming are as follows.

 

(1) Surrounding of chemically synthesized nanoparticles by organic surfactant molecules or any other surface coating would affect the processes such as recombination or charge transfer, (2) The presence of organic surfactants around nanoparticles hinders the mobility of charge carriers in electronic devices, (3) These molecules shield the active sites of the catalyst causing less catalytic activity than its potential, and (4) since they are not detached from particles they may be toxic when used in biomedical applications.

Schematic representation of chemically synthesized nanoparticles surrounded by organic surfactant molecules and their interactions.

 

However, we have developed novel HMDS-assisted methodology to synthesize metal sulfide and selenide (CuS, Cu₂S, CuInS₂, CuInSe_2, AgS, CdS, PbS, PbSe and BiS) nanoparticles which are free from any organic impurities. These materials have an enhance efficiency in various fields.

Schematic representation of HMDS-assisted synthesis of metal chalcogenides

 

Some of the surfactant-free nanoparticles have been used as catalysts in organic functional group transformation, degradation of organic dyes, and as photocatalysis in the purification of water.

Inorganic complexes - Catalysis

We have synthesized 2,5-bis{N-(2,6-diisopropylphenyl)iminomethyl}pyrrolyl complexes of Zn(II), Cd(II) and Cu(II) and studied their catalytic activities in carbon dioxide fixation. Using these complexes as catalyst a variety cyclic carboantes and phosphorous containing polycarbonates have been synthesized.

 

 

 

Polymer

We have designed polyethers using bis(hydroxymethyl)phosphine sulphides with an intrinsic disordered framework for Li-ion conductivity. The Li-ion conductivity of one of the solid polymer electrolytes showed the highest conductivity of 1.4 x 10^-4 S cm^-1 at room temperature. In addition, the presence of phosphorus in these polymers is expected to bring flame-retardant property to the electrolyte. These results are of great utility in improving the efficiency of Li-ion batteries.

 

High-energy materials

We have synthesized boron rich hybrid inorganic-organic salts using closo-dodecaborate [(B₁₂H₁₂)^2-] as anion imidazolium, triazolium and tetrazolium and other nitrogen rich cations.

Single-pot synthesis of zinc nanoparticles, borane (BH₃) and closo-dodecaborate (B₁₂H₁₂)^2- using LiBH4 under mild conditions

We have synthesized a variety of nitrogen rich molecules from triazole and tetrazole and studied their energetic properties

Our research proved that the solution phase synthetic method can be used to obtain Al-nanoparticles stabilized in matrices of poly(vinylpyrrolidone), poly(methylmethacrylate) and dextrine. The polymer stabilized nanoparticles were tested to be stable (without oxidation) atleast for ten months in open atmosphere.