Accelerated materials development for solar-to-fuel conversion technologies*

Renewable energy conversion and utilization technologies have made great strides in the past few decades, yet their integration into the energy distribution infrastructure has been relatively limited owing partly to the intermittent nature of these energy sources. Solar-to-chemical fuel conversion technologies have been attracting broad attention as a possible solution to address this problem by enabling a highly scalable energy buffering system. In particular, photoelectrochemical (PEC) hydrogen production approaches have been being studied extensively in past several decades, through which the scientific community has identified several fundamental issues that need to be tackled. In this talk, we will first review these issues, namely the time scale of the relevant elemental processes, the scaling relations of reaction energetics and kinetics, and the bifurcation behavior in macroscale systems that is dictated by the energetics and kinetics of atomistic processes. We will then discuss the potential solutions for the individual problems, which ultimately need to be addressed simultaneously. For example, a PEC device consists of a photoabsorber and co-catalysts, and for each component both rational design and combinatory search methods are being applied with some successes [1-3] with occasional surprises at the PEC device level that originate from the interplay between the individual device components [4,5]. Finally, we will discuss the prospects for a theory-experiment integrated approach in accelerating the development of new materials for PEC devices.

[1] Choi et al. J. Phys. Chem. C 117, 21772 (2013).
[2] Choi et al. Adv. Ener. Matt. 5, 1614 (2015).
[3] Liu et al. Nat. Ener. 6, 17127 (2017).
[4] Wood et al. J. Am. Chem. Soc. 135, 15774 (2013).
[5] Esposito et al. Nat. Mat. 12, 562 (2013).