(353g) Solution-Processed Semiconductor Photoelectrodes for Solar Fuel Production

High-efficiency direct solar-to-fuel energy conversion can be achieved using a photoelectrochemical (PEC) device consisting of an n-type photoanode in tandem with a p-type photocathode. However, the development of robust and inexpensive photoelectrodes are needed to make PEC devices economically viable. In this presentation our laboratoryâ??s progress in the development of economically-prepared, high performance photoelectrodes will be discussed along with the application toward overall PEC water splitting tandem cells for H₂ production. Specifically, this talk will focus on the application of Ï?-conjugated organic semiconductors and 2D transition metal dicalcogenides as solution-processed photoelectrodes.

With respect to Ï?-conjugated organic semiconductors, while their promising aspects have motivated intense investigation for economical roll-to-roll organic photovoltaic (OPV) devices, due to their poor stability in aqueous conditions, they have not been generally pursued as photoelectrodes for direct solar fuel production. In our recent work [1] we demonstrate a Ï?-conjugated organic semiconductor for the sustained direct solar water oxidation reaction. The water oxidation photocurrent density was found to increase with increasing pH and no evidence of semiconductor oxidation was found over testing time on the order of hours with bare BBL films. Molecular O₂ evolution was measured upon functionalization with a Ni-Co catalyst. Overall this demonstration suggests that robust n-type conjugated organic semiconductors are suitable for direct PEC water oxidation and opens a new path for the rational design and optimization of photoanodes for solar water splitting.

In addition, two-dimensional (2-D) transition metal dicalcogenides (TMDs) generally have intriguing electronic properties making them promising candidates for high-efficiency solar energy conversion. However, it is notoriously difficult to fabricate thin films of 2-D TMDs over the large areas required to harvest solar energy on a practical scale. We recently developed a simple method to fabricate high-quality thin films of 2-D layered TMDs at low cost and with good efficiency towards solar-to-fuel energy conversion [2].

Overall, the challenges with charge transport, separation and water redox catalysis in these systems will be discussed.

References

[1] Bornoz, P.; Prevot, M. S.; Yu, X.; Guijarro, N.; Sivula, K., J. Am. Chem. Soc. 2015, 137, 15338-15341

[2] Yu, X.; Prevot, M. S.; Guijarro, N.; Sivula, K., Nat. Commun. 2015, 6, 7596.