Start of funding 01.01.2010

Electrokinetic Co-generation of Hydrogen and Electricity

Prof. Dr. Roland Netz
Technische Universität München

Prof. Dr. Richard J. Saykally
University of California, Berkeley
Department of Chemistry



Due to the environmental impact of fossil fuel consumption, the search for efficient alternative energy sources is becoming crucial. It was recently shown that the simultaneous co-production of gaseous hydrogen and electrical power is possible using microjets of liquid water. The energy efficiency is approximately 10%, and design changes have to be considered for a significant improvement in efficiency. In this collaboration, we apply modern theoretical models and non-equilibrium molecular dynamics to examine the influence of various parameters on the electrokinetic charge separation in liquid microjets: the nature of the surface (hydrophobic, hydrophilic, charged, metallic), the composition of the aqueous liquid (ionic environment, pH), and the influence of temperature, pressure, and flow rate are studied. The modeling prediction are guidelines for ongoing experimental efforts.

Final report:
In the Saykally group it was recently shown that the simultaneous co-production of gaseous hydrogen and electrical power is possible using microjets of liquid water, which is potentially relevant in connection with the search for efficient alternative energy sources and energy transformation technologies. The mechanism has to do with the preferential adsorption of H3O+ at the water surface in conjunction with kinetic charge separation, which is quantified by the so-called streaming potential. To increase the energy efficiency, which currently is approximately 10%, it seems useful to be able to quantitatively model the experimental data. In three visits of the PIs at UC Berkeley the necessary model refinement were discussed. First we developed quantitative models to correctly reproduce experimental Zeta potential data at simple model surfaces. Here it proved necessary to include both the viscosity and the dielectric water interfacial profiles into the modified electrokinetic theories. These profiles were extracted from suitably modified atomistic simulations. On the other hand, in order to obtain reliable H3O+ distributions at water surfaces, we started developing accurately benchmarked H3O+ force fields. This work is still ongoing.