Aspects of Light‐Driven Water Splitting

This chapter involves using stable inorganic materials (mainly semiconducting oxides) for light-driven water splitting. The similarities with photosynthesis are reduced to the three steps: light harvesting; charge separation; and electron transfer. These processes are the basic components of “semiconductor photoelectrochemistry,” a topic that the author was first encouraged to investigate by Martin Fleischmann. The chapter outlines the basic physics and chemistry involved in light-driven water splitting at semiconductor electrodes, and also provides a brief overview of some of the problems that arise when trying to apply “traditional” models to light-driven water-splitting reactions. In quasi-Fermi levels, it is the entropic logarithmic terms in the electrochemical potential. To simplify the analysis, recombination in the space charge region is ignored, and surface electron–hole recombination is formulated in terms of the surface concentration of majority carriers present in the dark.