Coal fuels more than 40% of global electricity production, and is responsible for over 40% of global CO2 emissions. Further, coal is widely distributed across the Earth, and demand continues to grow. While we continue to develop alternative and renewable power sources, the capture and sequestration of CO2 from flue gas in fossil fuel power plants and other industrial processes is one viable solution to decrease our CO2 emissions. CO2 can be removed from flue gas by chemical looping, where a material chemically reacts with CO2 and is treated at a later stage to release pure CO2 and regenerate the starting material.
Limestone, CaCO3, is the oldest material to be used for this purpose. However, although limestone is abundant and cheap, the CO2 absorption capacity rapidly decays with use because of undesirable changes to the microstructure. To address the low performance of exisiting materials and enable CO2 looping as a possible technology that can be implemented at scale, new materials must be developed that have high selectivity for CO2, high absorption capacity, durability over many cycles, and reasonably fast kinetics for CO2 absorption and desorption processes.
Developing new high-performance materials is critical to enable next-generation technologies, which are essential to implement large-scale sustainable energy infrastructure and pursue a carbon-neutral footprint. However, breaking out of the known composition space to discover new materials is a difficult challenge in all materials disciplines, and many of the most notable materials classes under investigation today were discovered fortuitously.
Given the difficulty and slow pace with which new material discovery has traditionally occurred, computer-aided materials discovery may now provide the ability to systematically explore chemical whitespace and increase the rate of material discovery and technological progress. Toward this goal, this project has developed and applied computer-aided high-throughput methods to discover new functional materials, which we have prepared and characterized.
Within this larger goal of materials discovery, this project sought to discover new CO2 looping materials that have robust mechanical stability, as determined by their ability to absorb CO2 repeatedly over many cycles. As part of this, this project focused on exploring structural transformations and preparing and investigating novel ternary oxide ceramics designed to be mechanically stable after repeated structural transformations, such as those induced by thermal and CO2 cycling in CO2 capture materials. The new approaches to material design developed and applied in this project will be immediately relevant to many other scientific fields where chemical transformations and mechanical stability are critical, such as battery electrodes, solid oxide fuel cells, solid ion conductors, and catalysts, all of which suffer from performance loss over time due to microstructure changes.
CONCLUSIONS: We have applied a high-throughput prediction and screening method based in first principles calculations (density functional theory, DFT), and have prepared and characterized 12 candidate materials. The material properties agree with calculated properties, and validate this as a useful method to explore new CO2 looping materials.
Using this high-throughput method, we have discovered new materials with CO2 sorption capacities that do not degrade after 25 cycles. One of these materials displays low sorption capacity, but rapid sorption in less than 10 minutes, which may make it suitable for niche applications. Further, we have developed and experimentally validated a high-throughput materials prediction engine using machine learning methods, which may serve as a powerful route to accelerate the rate of new functional materials discovery.
