Theory and Computation in Photo-Electro-Chemical Catalysis: Highlights, Challenges, and Prospects

Computation and simulation is a powerful approach to aid in characterizing, understanding, and ultimately making predictions about materials, processes, and systems for efficient and cost-effective photo-electro-chemical (PEC) conversions of solar energy to fuels, one of the essential elements of broad strategies toward renewable energy. Solar energy-driven water splitting using semi-conductor-based photo-catalysts is perceived as the most desirable opportunity. For robust PEC technologies, viable materials and systems must exhibit good visible light absorption and carrier generation, good carrier transport, and good carrier redox reactivity. Overall conversion efficiencies of systems have improved in recent years. Challenges remain to achieve the needed performance characteristics, including several fundamental science issues toward the discovery and development of semiconductor photo-electrode materials that permit high overall efficiency in devices. Modern first principles-based multi-scale approaches are proving extremely valuable in providing fundamental understanding of many experimental observations in PEC catalysis. Here we highlight illustrative examples of the application of theory and computation to study carrier transport and carrier utilization in semiconducting electrodes. The examples address strategies to enhance charge carrier separation and strategies to mitigate stability and high over-potentials in redox reactivity of carriers. The growing body of computational studies in these areas suggests a bright and impactful future of theory and computation in the field of renewable and sustainable energies.