ENERGY CATALYSIS

Conversion of water and carbon dioxide to fuels using solar energy

Replacing fossil fuel-based energy with renewable sources is a critical step that society needs to take to meet future energy demands and combat climate change. While solar energy is attractive owing to its abundance, its intermittency necessitates the development of a scalable storage mechanism, which presently bottlenecks the implementation of solar energy at the scale of human consumption. For the future energy needs of society (10’s of terrawatts), solar fuels present the only scalable method of storage.

Water Splitting

Solar-to-fuels storage schemes necessarily rely upon water as the initial source of reducing equivalents, whether hydrogen is used as a fuel directly or converted with carbon dioxide to a liquid fuel. We are creating new oxygen evolution catalysts using earth-abundant elements that can operate with high activity and long-term stability under a variety of conditions owing to the invention of new processes, such as self-healing catalysis. We have also recognized the importance of utilizing seawater and other abundant impure water sources without pretreatment or purification by developing new water-splitting strategies. Our work allows hydrogen and pure oxygen to be generated from solar light + any water source. The ability to use benign water sources allows for the facile integration of water splitting catalysts with light absorbers leading to the creation of devices such as the Artificial Leaf—the first totally wireless solar water splitting device.

Carbon Dioxide Reduction

Solar generated hydrogen may be converted to a liquid fuel by combining it with carbon dioxide. Current carbon dioxide reduction (CDR) strategies confront the limitation of low carbon and energy efficiencies owing to the reaction of hydroxide with carbon dioxide to produce super-stoichiometric amounts of bi/carbonate. In addition to developing new CDR catalysts, we have therefore focused on the design of tandem catalyst strategies where newly discovered CDR catalysts work in concert with a secondary catalyst to clear bi/carbonate from solution. Such approaches focused on carbonate greatly enhance the energy and carbon efficiencies of CDR catalysis and in doing so offer a path for a viable and authentic solar-to-liquid fuels technology at large scale.