Creating a solar fuel from sunlight, water and carbon dioxide is a complex task drawing inspiration from a process that was optimized millennia ago – photosynthesis. Artificial photosynthesis mimics the process of photosynthesis, however, rather than grow a plant, solar fuel scientists want to create a fuel.
Developing an artificial photosynthetic system involves multiple scientific disciplines – chemistry, materials science, and engineering to name a few. As researchers continue to make breakthroughs in the field of solar fuels, the science will continue to evolve and we will continue to highlight these advances both on our blog and in the adjacent brief segments.
Natural photosynthesis begins with the capture and absorption of sunlight. That light energy is then transported and used to split charges. The charges are further transferred to catalytic sites to perform the fuel forming reactions.
SOFI scientists aim to convert the sun’s energy into clean fuels by following nature’s blueprint – through artificial photosynthesis. SOFI researchers are using a variety of state-of-the-art methods, such as molecular sensitizers, nanoarchitectures, organic dyes, semiconductors, and plasmonic devices, to enhance the capture and utilization of light energy.
Scientists are developing artificial light-harvesting systems to span the entire spectrum that is useful for solar fuel production (400 nm − 1000 nm). They are implementing novel designs to efficiently transport the absorbed energy to artificial reaction centers that then separate the negative and positive charges. The photoinduced electron transfer events can then drive the various fuel forming reactions pursued by SOFI researchers.
All fuel-forming reactions and catalysis involve moving electrons from one species to another, a.k.a. redox chemistry (combination of “reduction” and “oxidation”). In order to store the energy from the sun in the form of fuels, researchers will need a clean source of electrons.
Nature’s source of electrons in photosynthesis comes from water. Electrons can be derived from the conversion of water molecules into their constituent oxygen gas and positive hydrogen ions (oxidation). This process, however, is very difficult, and requires special substances— catalysts— to facilitate that reaction.
SOFI researchers are developing new catalysts that use earth-abundant elements to split water, either by an electrical potential or by a light-driven process.
Humans are emitting carbon dioxide (CO2) at an unprecedented rate by burning fossil fuels for transportation and electricity generation, which is driving global climate change. Photosynthesis originally converted that CO2 into the organic matter, which, over millions of years, turned into the coal and oil we are extracting from the ground today.
Recycling CO2 (obtained from flue gas from smokestacks or extracted from ambient air) to produce liquid fuels can provide near-term solutions that fit within the existing energy infrastructure and can mitigate the negative effects of dirty energy sources.
Of particular interest is the reduction of CO2 to CO, which, as a component of synthesis gas (syngas), can be converted to methane, synthetic petroleum, or other liquid fuels using commercially mature technologies.
SOFI researchers are developing new catalysts that waste less energy, are more efficient, and have greater longevity.