Water-Splitting for Solar Fuel Devices

Social environmental concerns about global warming and CO₂ emissions provide the stimulus to find the way to replace fossil fuels by solar fuels. In this context, sustainable energetic schemes should be based on the conversion of abundant energy-poor molecules (such as H₂O) into energy-rich molecules (as for example H₂) using sunlight as the energy source. This solar fuel can be easily stored, transported and used upon demand in fuel cells, where the reverse reaction takes place to convert chemical energy into electricity. This is one of the key challenges of the twenty-first century and multidisciplinary work is needed to succeed in transforming the theory into practice.To achieve a practical technology, low-cost materials and earth-abundant catalysts are required to be used for both reactions (water splitting and H₂ oxidation into water). In the present talk, we report the production of solar fuels with low-cost materials based on organic chemistry (3). The synthetic versatility of these materials and understanding of the energetic aspects provides the design rules to extract the generated photocurrent in the organic blend to the electrolyte solution in the scale of mA·cm^-2. For technological application, the rational design of the harvesting light material (the organic blend), the interfacial selective layers (hole and electron selective layers) and the catalyst are equally important. Herein, the study of the electron selective layer and catalyst (noble-metal free) are researched towards optimising both H₂ production rate and stability in these devices.

References:

[1] H. B. Gray, Nature Chem. 1, 7 (2009)

[2] S. W. Cha, W. Colella, F. B. Prinz, Fuel cell fundamentals New York: John Wiley & Sons (2006)

[3] A. Guerrero, M. Haro, S. Bellani, M. R. Antognazza, L. Meda, S. Gimenez, J. Bisquert, Energ. Environ. Sci. 7, 3666 (2014)