Swathi Sunkara, Venkat Kalyan Vendra, Jacek Bogdan Jasinski, Todd Deutsch, Antonis N. Andriotis, Krishna Rajan, Madhu Menon, and Mahendra Sunkara

Photo-electrochemical (PEC) water splitting and photocatalytic carbon dioxide reduction are the most promising approaches for utilizing solar energy to produce clean fuels.

The practical implementation of the PEC water splitting technology using sunlight is discovering a suitable  material that will simultaneously satisfy a number of criteria including: (i) the material to posess the correct band gap; (ii) the redox potentials of the water reactions should be included within the energy range of the band gap, and (iii) the material to be stable against corrosion.

In a series of recent papers, Dr. Antonis Andriotis (IESL/FORTH) and Prof. Madhu Menon (University of Kentucky in Lexington, KY, USA) predicted that GaN (with a direct band gap of 3.45 eV) can be engineered to have its band gap value drastically reduced to approximately 1.5 eV if doped with Sb up to 8 at%. In addition, it was predicted that the redox potentials of H₂O could be included within the range of the energy gap of GaSb_xN_1-x (x < 8%). These predictions make GaSb_xN_1-x a very promising material for water splitting in the visible regime.

The predictions of Andriotis and Menon have recently been verified experimentally by a series of experimental tests performed by the group of Prof. Mahendra Sunkara (Department of Chemical Engineering and Conn Center for Renewable Energy Research, University of Louisville). Additionally, the corresponding photo-electrochemical data on activity and stability suggest that these alloys are highly suitable for solar water splitting.

This work (theory and experimental details) has recently appeared in the (high impact factor journal) of Advanced Materials: DOI: 10.1002/adma.201305083; (2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).

Antonis Andriotis
Research Director
IESL/FORTH , 25 February 2014