Nature-inspired energy storage developments

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Biomimetics, which studies biological systems in order to imitate them and apply them to disciplines like modern medicine and engineering, is a rapidly expanding field which is making leaps and bounds in broadening its sphere and increasing its harnessing potentials. In recent years, a deeper understanding of complex biological systems has given rise to many new areas of technological research, areas that are now producing consumer and industrial grade products and services.

For example, nanoscale systems such as the shells of viruses are favoured for their environmental stability; these can withstand temperatures up to 60oC, as well as a wide range of pHs are are thus being adapted for various uses, from nanotube synthesis to crystal nucleation. On a larger scale, trains in Japan are benefiting from the aerodynamic beak shape of the kingfisher. Other examples include silkworm silk, which led to the invention of Kevlar for bulletproof vests, and the bombardier beetle’s mist forming gland, which is used to spray a repellent and which has led to the development of aerosol-free spray cans.

Energy production and storage is a research area of notable importance and the field has recently turned to biomimetics to solve some of the challenges it is facing today. Evolutionary evidence has shown that the concept of storing energy in the form of a chemical bond is efficient, and animals and plants operate on systems which revolve around this concept. One system that researchers are interested in is photosynthesis, which is the primary energy production method for most plant species on Earth and which involves storing energy directly in a chemical bond. The process takes carbon dioxide and water and produces oxygen and glucose, a sugar. Light energy is captured in proteins called reaction centres, where photons are funnelled down and used to split water molecules into oxygen and hydrogen ions. The energy from this is then transferred through various other steps, incorporating the carbon dioxide.The residual energy is then stored in the bonds of the new sugar molecule within the plant and the oxygen is released as a waste product.

Recent research into catalytic water splitting by the Wang group at Boston College has taken this natural process one step further. Although many water oxidation catalysts already exist, the group have developed an improved photochemical synthesis method to produce a dinuclear heterogeneous catalyst (DHC), which contains iridium, a material which naturally absorbs visible light. What separates this catalyst from similar products is its dinuclear active site – a site consisting of two iridium atoms –  which is an accurate molecular representation of the photosynthetic active site in chlorophyll. The dinuclear active site offers several advantages, such as increased stability, efficiency and activity and more selectivity towards water splitting. Moreover, similar catalysts such as single atom catalysts and nano-particles have been thoroughly documented, which makes DHCs easier to understand and perfect.

Inspired by the reaction centre vital to photosynthesis, the dinuclear iridium catalyst is said to operate at higher efficiencies and at a lower cost than photosynthesis. This is a platform being built upon towards the goal of developing technology for the direct storage of solar energy. As global plant energy production far exceeds human consumption, once again we are drawing inspiration from nature in order to develop solutions to the problems we face today.

This article was written by Blair Donaldson and edited by Teodora Aldea

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