Developing Devices that use Biotemplated Nanoparticles for Sustainable Energy Generation

In this project I will take inspiration from Nature to develop sustainable materials that capture light energy, and use these to make solar cells.

The UK and EU have set climate neutral targets to reach by 2050. One way to contribute to this is to switch from burning fossil fuels to using renewable energy sources, such as solar power. Plants use complicated photosynthetic molecules to harvest light energy. Unfortunately, these molecules are too delicate for us to use for industrial scale light harvesting. In their place, we use minerals that are able to convert light into electricity in solar cells, or into chemical reactions for catalysis. These optically active nanoparticles are also great for making colourful displays and for imaging. Making these mineral nanoparticles usually needs high temperatures (200 Celsius), dangerous solvents (toluene, acetone, etc.) and toxic elements (e.g. cadmium, lead). To meet the 2050 net-zero targets, we need to develop high-quality light capturing nanoparticles that are made at room temperature in mild solvents (like water) and from safer, more abundant elements. Here I will develop kinder methods of making cadmium and lead-free optically active nanoparticles.

Natural biominerals; such as bones, teeth and shells; are made by biomolecules that control the size, shape and type of mineral that is formed with precision. These biomolecules include proteins, which have evolved to specifically bind to and template natural biominerals. The proteins do this in water, at ambient temperatures and using elements that are abundant on Earth. We have not found light harvesting nanoparticles amongst these naturally occurring biominerals, so I will use tools from Nature to make them. I will use biological scaffolds that display a specific protein, and mix billions of them with light harvesting nanoparticles. This will allow me to pick out proteins that specifically bind to the nanoparticle surface.

Binding to a surface is not the same as making a particle from solution, so I will improve the binding proteins into templating proteins. The size and elemental composition of an optically active nanoparticle needs to be precisely controlled to get a uniform absorption and emission of light. High-temperature solvent processes are currently used to impart this control. Biotemplating proteins are able to bind to specific sides, corners or edges of a growing crystal through short sections of the protein called peptide sequences. In this way, these peptide sequences control the properties of the biotemplated crystal with precision.

There are too many possible peptide sequences to test them all, so I will develop computational tools to help me to select the best ones. I will design sequences to test based on the binders discovered above, and I will monitor the colour of the forming nanoparticles to find the best templating peptides. The best ones will be used to make optically active nanoparticles from water and at room temperature. I will also use computational tools to study how the biomolecules bind to these target surfaces and template the nanoparticles from solution.

I will pattern the biotemplating peptides on surfaces. This will allow me to form optically active nanoparticles on surfaces, under mild conditions. These surfaces will be used as components to build devices for light harvesting in solar cells and for catalysis. I will build solar cells using these biotemplated materials, and test their durability and efficiency, showing that they work. I will also test these materials for use in making hydrogen from water, and for use in displays. The colourful materials I develop to do this will also be used to make interesting art-science collaborations to showcase this research. The green methods I will develop here will contribute to ways of making devices for a sustainable climate neutral 2050.