Light harvesting and charge transfer in metal oxide nanomaterials for hydrogen energy generation

Photoelectrochemical cells, PEC represent an important class of devices generating solar-hydrogen and create an attractive alternative to the traditional power sources. Practical application of PEC is hindered by numerous drawbacks of semiconducting light absorbers, the most important being: a mismatch between the spectrum of Sun and the fundamental absorption of the semiconducting photoanode. This review is devoted to new solutions related to the light harvesting and charge transport issues in TiO2-based PEC. Light management based on fitting the sunlight spectrum to the sensitivity of the device via a wavelength-shift operation, such as up-conversion, is proposed. Charge transport schemes required to reduce electron-hole pairs’ recombination depend on the form of the photoanode material with 1D nanorods and nanotubes being considered the best suited for this purpose.