Why in news?
DST INSPIRE Faculty develops nanomaterials having energy storage application & optical sensors for water pollution control.
- Increasing energy demand due to the growth of human population and technological advancement poses a great challenge for human society.
- High energy density of supercapacitors suggests that constant current can be withdrawn for longer duration without recharging.
- Hence automobiles can run longer distances without charging. Supercapacitors can be an alternative for such purposes.
- DST team developed a reduced graphene oxide (rGO) at a moderate temperature of 100°C with high capacitance performance.
- The production process is a cost-effective one, making it suitable for commercial purposes.
- The group which works on carbon (Carbon Nanotubes, Graphene) and metal dichalcogenides (MoS2, MoSe2, etc.) nanomaterials based supercapacitors to achieve high energy density and power density of supercapacitors, have also developed a novel green approach for synthesis of Iron-based nanocatalyst, which can be used for large scale production of Cabon Nanotubes.
- They are working on developing novel nanostructures of carbon and metal dichalcogenides semiconductors for photodetection and Surface-Enhanced Raman spectroscopy (SERS).
- Through this work, they have demonstrated excellent photodetection behaviour of different architectures of nanoscale MoS2 for the detection of visible light.
- The high photoresponsivity obtained in this work can be useful to develop ultrafast detectors for signalling purpose.
- The SERS can help detect harmful molecules present in water at ultra-low concentrations.
- This group has successfully demonstrated detection of Rhodamine 6G (R6G), an organic laser dye up to lowest limit of sub-nano-molar concentration using rGO and MoS2 nanomaterials.
- Their focus on energy and optoelectronics devices paves the way for the development of cost-effective and efficient devices, which can be used for energy storage application.
- Their findings make way for materials which can be used as advanced photodetectors and also be used as optical sensors for water pollution control.
What is photoresponsivity?
Responsivity measures the input–output gain of a detector system. In the specific case of a photodetector, responsivity measures the electrical output per optical input.
The responsivity of a photodetector is usually expressed in units of either amperes or volts per watt of incident radiant power. For a system that responds linearly to its input, there is a unique responsivity. For nonlinear systems, the responsivity is the local slope. Many common photodetectors respond linearly as a function of the incident power.
What is graphene?
Graphene is the name for an atom-thick honeycomb sheet of carbon atoms.
Harder than diamond yet more elastic than rubber; tougher than steel yet lighter than aluminium. Graphene is the strongest known material.
To put this in perspective: if a sheet of cling film (like kitchen wrap film) had the same strength as a pristine monolayer of graphene, it would require the force exerted by a mass of 2000 kg, or a large car, to puncture it with a pencil.
Graphene possesses other amazing characteristics:
- Its high electron mobility is 100x faster than silicon;
It conducts heat 2x better than diamond;
- Its electrical conductivity is 13x better than copper;
- It absorbs only 2.3% of reflecting light;
- It is impervious so that even the smallest atom (helium) can’t pass through a defect-free monolayer graphene sheet;
- Its high surface area of 2630 square meters per gram means that with less than 3 grams you could cover an entire soccer field (well, practically speaking you would need 6 grams, since 2630 m2/g is the surface area for both sides of a graphene sheet).
- Graphene is widely used in making solar cells, light-emitting diodes, touch panels and smart windows. Graphene supercapacitors serve as energy storage devices with a capacity for faster charging and longer life span than traditional electrolytic batteries.
- Other potential applications of graphene include water filtration and purification, renewable energy, sensors, personalised healthcare and medicine, to name a few.