Team Dey

Research

Multi-scale modeling of hydrogen effects on materials

Hydrogen (H₂) will be an increasingly important fuel in the future green economy. It is an ideal green fuel because it is renewable, lightweight, nontoxic in nature, and available in enormous amounts. Known bottlenecks in the efficient large-scale realization of H₂-based technologies are the control over the production, storage and release, as well as the safe transportation of H₂. To establish a viable ‘H₂-based economy’, it is crucial to design materials with properties that allow overcoming these bottlenecks. For instance, the materials for H₂ storage applications should fulfill various requirements such as low weight, robustness (i.e. prevent hydrogen embrittlement), being easily synthesizable and have a low cost. Such materials should have rapid adsorption and desorption kinetics in order to act as reversible H₂ storage media.

One of our research interests lies in understanding hydrogen interaction with microstructural features at atomistic level in order to make materials, e.g. steels, better resistant to hydrogen embrittlement (HE). Within the framework of our NWO funded project, we are collaborating with Dr. Vera Popovich (MSE department, TU Delft) and Dr. Francesco Maresca (University of Groningen) to obtain deeper insights into the underlying mechanisms of HE. The underlying approach of the project is based on multi-scale modelling-experimentation synergy based on Density Functional Theory, Molecular Dynamics, Crystal Plasticity and advanced experimental characterization that will connect atomistic information with the microstructural behaviour of multi-phase steels in presence of hydrogen, enabling design of new steels that are resistant to HE (Fig. 1). The novel methodology developed within the project for steels, will be transferrable to other technologically relevant materials e.g. superalloys and the novel high-entropy alloys. Our research interest also lies in the identification and optimization of materials for efficient H₂ storage based on multi-scale approach combining quantum mechanical Density Functional Theory (DFT) calculations on phase stability with Molecular Dynamics (MD) simulations on atomistic kinetics. Together with our colleagues from P&E department of TU Delft, Dr. Othon Moultos and Prof. Thijs Vlugt, we are investigating the hydrogen storage efficiency of two-dimensional materials such as boron-based materials and graphene (Fig. 2).
 

Tailoring material properties to design thermoelectric materials with improved performance

Thermoelectric energy generation technology has opened up a potential route for the efficient conversion of waste heat into valuable electrical energy. Given the huge amounts of heat energy wasted by industry - one estimate suggests up to 68% - there is huge potential for large-scale thermoelectric power generation. Higher energy conversion efficiency can be achieved by maximizing the ratio of electrical and thermal conductivity for thermoelectric materials with a high Seebeck coefficient. The intercoupling feature of the physical parameters, i.e. Seebeck coefficient, electrical and thermal conductivity, however makes it a long-lasting challenge to obtain high-energy conversion efficiency. My research activities focus on computation-based designing of thermoelectric materials with optimized performance. One of the materials of my interest is the half-Heusler alloy. These alloys have attracted enormous attention because of their desirable properties such as good values of the thermoelectric figure of merit, robust mechanical properties, high-temperature stability, low cost and usage of non-toxic and earth-abundant elements. I, together with my collaborators from Korea Advanced Institute of Science and Technology (South Korea), proposed a novel approach to fabricating thermoelectric material with nanostructures to increase energy conversion efficiency (Fig. 3).