Harvesting energy and its clean utilization has become one of the major challenges of the world. The annual world energy consumption has reached 4.1 1020 joules and it is believed to double in 2050. Currently, we are getting about 80% of our energy from fossil fuels and 20% from other sources like biomass, nuclear and hydropower. It is believed that there are abundant fossil fuels present in the world that can provide energy up to 100, years but still it is a finite source. Moreover, by the combustion of fossil fuels, a huge amount of different oxides (COx, NOx, and SOx) are released, which harm the environment. So, the world is moving towards alternative renewable energy technologies such as solar cells, biofuels and fuel cells to get cheap and clean energy.
The alternative technologies have some limitations in material properties, as they have a low energy density, poor charge-carrier mobility, and some other problems. To overcome these problems, the researchers are focusing their interest in nanostructured materials, which are expected to give the solution for many challenges. Nanostructured materials have properties to improve the generation and transportation of electrons and ions, which will accelerate the efficiency of the system. Nanostructured materials have applications in photovoltaics, capacitors, batteries, thermoelectronics and other energy storage systems.
Sun is the most important energy source for all living organisms on earth. It is considered a carbon-free energy source, which is the ultimate solution to the clean energy challenge of the world. Crystalline silicon semiconductor photovoltaic cell was invented in 1954 and now it makes up to 90% of the market. Conversion efficiency and cost of the photovoltaic cell are two major challenges that limit the extensive use of this technology. Dye-sensitized solar cells showed high efficiencies and low cost due to the use of nano-porous semiconducting electrodes made of inexpensive TiO2. The nanostructured crystalline material is favorable because of its large surface area and effective transport of electrons.
Nanomaterials as electrodes and electrolytes may provide changes such as i) initiate the reactions that are not possible in the conventional system; ii) improve the contact area between electrodes and electrolytes leading to higher charge and discharge rate.
Furthermore, nanostructured materials have interesting applications in supercapacitors and fuel cells. Supercapacitors are electrochemical energy storage devices that have high energy storage and power delivery abilities, and they are available for different applications. Therefore, supercapacitors are playing an important role in the improvement of fuel economy, reducing harmful emissions and decreasing the reliability of fossil fuels. The world is moving to enhance the performance of supercapacitors to meet the precise requirement as mentioned above and to make it applicable for other advanced applications.
In any energy storage device, the selection of electrode materials and the electrolyte is important to describe the performance of the cell. Nanostructured materials consist of large surface area, good electrolyte accessibility, and high mesoporosity, which make them a good candidate to replace conventional materials.
In this essay, I have briefly highlighted the significance of the development of nanostructured materials for their application in energy storage devices (photovoltaic cells, batteries, supercapacitors and fuel cells). Still, there are so many challenges to make it practically feasible. Moreover, theoretical approaches are strong tools and play a vital role to give the solution for existing challenges.