With the advent of large structural databases containing both optimised crystallographic structures and their ground state energies, the goal of rationally designing novel functional materials for a variety of applications can be realised. Through selection of relevant, property-specific parameter(s), screening criteria can then be applied to thousands of potential candidates in silico, efficiently selecting the most promising materials for subsequent experimental testing. Here we describe our work developing screening methodologies for the design of novel materials for carbon capture and storage (CCS) and ionic conductivity. Our holistic approach combines theoretical screening with experimental validation to better understand the trends underpinning the performance of the selected materials. We have made use of the Materials Project database (www.materialsproject.org), which not only contains an extensive variety of calculated structures, but is also constructed in such a way to be amenable to high throughput screening. The first application we consider is CO2 absorption looping for CCS, which requires oxide materials that are able to reversibly absorb CO2 at high temperatures. CaO is the prototypical material for this application, but unfortunately suffers irreversible capacity loss and sintering upon continuous carbonation-regeneration cycles, necessitating materials with improved performance. With large scale screening, we were able to simulate the carbonation equilibria for 640 prospective sorbents and then select a number of candidates based on (i) minimising the energy cost associated with their use and (ii) maximising their theoretical CO2 capture capacity [1]. The accuracy of the screening was validated using structural and thermogravimetric analysis, and the process led to a number of design rules for optimising materials performance, including focussing on ternary oxides and materials containing magnesium and calcium. The second part of this work concerns another CCS technology, chemical looping combustion, which utilises materials that can spontaneously release gaseous O2 in order to efficiently burn fuel in a N2-free environment and create pure CO2 for subsequent capture. This is in contrast to the former process, which separates CO2 post-combustion. Binary metal oxides with multiple oxidation states such as CuO and MnO2 can be reduced under reactor conditions, but materials that reduce at lower temperatures and cycle more stably are desirable in order to minimise energy costs involved with combustion at higher temperatures. Our screening found over 2200 materials that were able to undergo redox reactions under the specific process conditions [2], with further experimental studies revealing a number of promising materials that could be stably cycled between their perovskite and brownmillerite phases. The final part details the use of local structural similarity algorithms to efficiently screen materials for oxygen ionic conductivity. Building on a previous methodology using Voronoi tessellations to ...

Amongst the many different processes proposed for large scale carbon capture and storage (CCS), high temperature CO 2 looping has emerged as a favourable candidate due to the low theoretical energy penalties that can be achieved. Many different materials have been proposed for use in such a process, the process requiring fast CO 2 absorption reaction kinetics, as * To whom correspondence should be addressed † Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom ‡ Department of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom ¶ Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom § Department of Engineering, University of Cambridge, Trumpington Street, Cambridge, CB2 1PZ, United Kingdom 1 well as being able to cycle the material for multiple cycles without loss of capacity. Lithium ternary oxide materials, and in particular Li 2 ZrO 3 , have displayed promising performance but further modifications are needed to improve their rate of reaction with CO 2 . Previous studies have linked rates of lithium ionic conduction with CO 2 absorption in similar materials, and in this work we present work aimed at exploring the effect of aliovalent doping on the efficacy of Li 2 ZrO 3 as a CO 2 sorbent. Using a combination of x-ray powder diffraction, theoretical calculations and solid-state nuclear magnetic resonance, we studied the impact of Nb, Ta and Y doping on the structure, Li ionic motion and CO 2 absorption properties of Li 2 ZrO 3 . These methods allowed us to characterise the theoretical and experimental doping limit into the pure material, suggesting that vacancies formed upon doping are not fully disordered, but instead are correlated to the dopant atom positions, limiting the solubility range. Characterisation of the lithium motion using variable temperature solid-state nuclear magnetic resonance confirms that interstitial doping with Y retards the movement of Li ions in the structure, whereas vacancy doping with Nb or Ta results in a similar activation as Li 2 ZrO 3 . However, a marked reduction in the CO 2 absorption of the Nb and Ta doped samples suggests that doping also leads to a change in the carbonation equilibrium of Li 2 ZrO 3 disfavouring the CO 2 absorption at the reaction temperature. This study shows that a complex mixture of structural, kinetic and dynamic factors can influence the performance of Li-based materials for CCS, and underscores the importance of balancing these different factors in order to optimise the process.