1. Earth-Abundant Next-Generation Materials for Solar Energy Conversion 

The energy trilemma - energy security, energy accessibility, and environmental sustainability is emerging as a critical challenge for the development of government energy policies. Meeting the ever-increasing global energy demands, while at the same time drastically reducing carbon emissions from the overreliance on and usage of fossil fuels remains one of the most critical challenges for humankind in the 21st century. Solar power has a tremendous capacity to provide society with clean energy by displacing coal and oil used for electricity generation and transport. The solar resource is super-abundant and freely available. Harnessing this energy and designing our infrastructure around it will mitigate the environmental and societal impacts of climate change. Today, solar technologies already contribute to varying degrees to national energy productions. However, for solar energy to be rapidly established as part of the mainstream electricity industry at a reduced cost, devices must be made from inexpensive and earth-abundant materials. Under this research theme, we employ cutting-edge materials theory and simulation to predict novel solar absorber materials composed of earth-abundant elements; and to engineer existing materials to improve their stabilities and solar conversion performance. Recurring themes here include bandgap engineering, interface engineering, band alignment and offset engineering. The magnitude of band offsets controls transport phenomena across interfaces and characteristics of PV devices, hence their accurate determination and engineering are vital to improving the performances of PV devices. 

2. Computer-Aided Catalyst Design

New catalysts are needed to improve the efficiency of industrial processes and drive energy conversion and environmental mitigation processes. Achieving the required catalytic performance (activity and selectivity) gains depends on exploiting the many degrees of freedom of materials development including multiple chemical components, nanoscale architectures, and tailored electronic structures. Using predictive modeling is the only intelligent and efficient path forward to sift through the many degrees of freedom. Under this research theme, we employ first-principles electronic structure calculations in collaboration with an experiment to provide reliable insights into the thermodynamics and kinetics/dynamics of the elementary steps involved in model catalytic reactions such as CO2 conversion, water splitting, and hydrogen evolution reactions (HER). The synergistic computational-experiments approach provides the most profound and detailed insights into how chemical reactions proceed and how we can control their finest details.

3. Computer-Accelerated Design of High-Capacity Battery Electrode Materials

The world needs more power, preferably in a form that’s clean and renewable. Our energy-storage strategies are currently shaped by lithium-ion batteries – at the cutting edge of such technology. Advanced, lithium-based batteries play an integral role in 21st century technologies such as electric vehicles, stationary grid storage, and defense applications that will be critical to securing a clean energy future. However, the current rapid development of society requires a major advancement in battery materials to achieve high capacity, long life cycle, low cost, and reliable safety. Therefore, many new efficient energy storage materials and battery systems are being developed and explored, and their working mechanisms must be clearly understood before industrial application. In recent years, first-principles methods based on density functional theory (DFT) calculations have become indispensable in the rational design of long-lasting, stable, solid-state lithium batteries. Such calculations have contributed significantly to the understanding of electrochemical reaction mechanisms and to virtual screening of promising energy storage materials. Under the battery research theme, we employ advanced theoretical methods based on DFT calculations to accelerate the exploration of high-performance battery materials and predict structure-property-performance relations in electrode materials. Our aim is to understand Structural stability, Electronic structures, Electrochemical reactions, Diffusion kinetics, and Adsorption kinetics. We are also interested in supercapacitors due to their high-energy capacity, storage for a shorter period, and longer lifetime. Here we are interested in predicting the binding energy of ions at the electrode surface, Quantum capacitance calculations, and unraveling interfaces in composite supercapacitor electrode materials. 

4. Chemical Functionalization of Nanoparticles

Nanoparticles have major impacts on fundamental research and many industrial applications due to their unique size- and shape-dependent properties such as electrical, magnetic, mechanical, optical, and chemical properties, which largely differ from those of the bulk materials. Because nanoparticles have different surface structures and thus different surface interactions compared to larger particles, they have an extremely high tendency toward adhesion and aggregation. It is therefore important to develop synthesis techniques to control the dispersion or aggregation of nanoparticles that dictate their crystal shape. Control of nanocrystal shape is important in various applications, such as in heterogeneous catalysis, solar cells, light-emitting diodes, and biological labeling. In particular, it offers promise for improving catalytic activity and selectivity through optimization of the structure of the catalytically active site. Generally, the synthesis of nanoparticles involves surfactant molecules that bind to their surface, which stabilize the nuclei and prevent larger nanoparticles from aggregation by a repulsive force between the adsorbates, thus controlling the growth of nanoparticles in terms of the rate, final size, or geometric shape. However, due to the complex nature of the interface between organic functional groups and nanoparticle facets, the interface chemistry is difficult to determine by purely experimental means. Under this research theme, we employ accurate first-principles calculations to predict the lowest-energy adsorption structures of organic molecules at inorganic surfaces. Insights into how the adsorption influences the stabilities of the different nanoparticle facets unraveled. Based on calculated surface energies, the final shape/morphology of the nanoparticle is predicted using Wulff Construction.

5. Surface Geochemistry and Computational Mineralogy 

Practically all environmentally relevant reactions in nature that involve minerals are surface or interface reactions. Be it crystal growth, adsorption reactions, mineral extraction and dissolution, redox reactions, or even the growth of crystallites from the melt, the actual reactions take always place at mineral surfaces. To understand and influence these processes it is desirable to obtain a detailed insight into the surface and interface interactions at the molecular level. Molecular simulations provide mechanistic insights into the adsorption process and accurately predict the structures and properties of the adsorption complexes of contaminants onto iron oxide-hydroxide and sulfide surfaces, which is critical for the quantification of the adsorption.

When it comes to the recovery of rare earth minerals from various sources, froth flotation is a commonly used technique. This involves the adsorption of both organic and inorganic reagents at the mineral-water interface, with the objective of selectively rendering the target mineral(s) hydrophobic to recover it in the froth phase. Collectors, which contain a polar group and a non-polar aliphatic chain, can be adapted in terms of chain length, unsaturation, and ramification, as well as functionalized polar groups. Moreover, all these reagents can be combined to improve the flotation performances (selectivity or target minerals recovery). All these optimizations are difficult to investigate by purely experimental methods and molecular modeling is a powerful tool to gain a detailed atomic-level understanding of the adsorption mechanisms of flotation reagents at the mineral-water surfaces. We aim to develop robust theoretical models and employ atomistic simulations (DFT and MD simulations) to describe the mineral-water interface and the adsorption mechanisms of collector molecules at finite temperatures and pressures in the froth flotation process. The derived atomic-level insights are expected to motivate rational design and selection of future collector molecules for enhanced recovery of critical minerals.