(6hb) Rational Design of Redox Materials and Catalysts for Conversion and Storage of Renewable Energy

This poster presents current and previous research on materials and technologies for renewable energy conversion and energy storage in the form of chemicals and chemical fuels. Generally, the presented work employs a dual approach, based on quantum-mechanical computations to understand and tailor the activity of a material for a certain application and lab-scale materials synthesis, reactor construction and experimental testing to verify trends, demonstrate concepts, and determine limitations. In addition to the presented work, I will discuss research plans aiming at an advanced understanding and development of chemical looping, heterogeneous catalysis and electrocatalysis for conversion and storage of renewable energy.

Specifically, the poster focuses on three examples for the production of solar-derived chemicals: First, metal oxide redox materials are developed for solar-driven production of syngas, the precursor for renewable liquid hydrocarbons. The performance of such metal oxides is limited by their oxygen conductivity and thermochemical stability, while the solar-to-fuel energy conversion efficiency of solar syngas production is limited by irreversible heat losses from the reactor. The poster introduces design principles for metal oxide redox materials and shows how to employ these for the development of advanced materials for a continuous and isothermal splitting of CO₂ and H₂O, which circumvents irreversible heat losses from heating and cooling of the redox material.

The second example focuses on rational design of electro- and heterogeneous catalysts for the production of synthetic hydrocarbons. The catalytic activity of a material is often limited by a strong correlation between the adsorption energies of reaction intermediates among the transition metals. The presented work demonstrates how the introduction of non-metals into metal catalysts confers to the material desirable activities due to systematic departures from adsorption energy scaling relations. The conclusions are shown to extend beyond atomic probe adsorbates to molecular fragments, making these concepts generally useful for the theory-based design of catalytic materials.

Finally, materials research for a solar-driven low-pressure synthesis of ammonia (NH₃) is presented. Ammonia is one of the most important synthetic chemicals in today’s economy. It is used as synthetic fertilizer, responsible for growing the food for approximately half of the world’s population, and has attracted attention as hydrogen carrier and as a direct substitute for fossil fuels in internal combustion engines. As an alternative to the industrial fossil fuel-driven synthesis of NH₃ at some of the most extreme conditions of the chemical industry, the poster presents work towards a sustainable production of NH₃ from N₂ and H₂O at ambient pressure via chemical looping of reducible metal nitride and metal hydride catalysts.