The microfluidic test-bed developed by the team allows for different anode and cathode materials to be integrated and electrically accessed independently through macroscopic contacts patterned in the outside of the micro-fabricated chip.

The transport of charge-carriers occurs through an ion-conducting polymer membrane, and electrolysis products can be evolved and collected in separated streams. This general design provides selective catalysis at the cathode and anode, minimization of cross-over losses, and managed transport of the reactants. Virtually any photoelectrochemical component, including those made of earth-abundant elements, can be incorporated into the test-bed.

In this microfluidic test-bed, a chemically inert wall (red) separates anode from cathode and the channels in which O2 and H2 are generated by splitting water molecules. Protons (H+) are conducted from one channel to the other via a membrane cap (Nafion) that also prevents the intermixing of the O2 and H2 product streams. Source: Berkeley Lab. Click to enlarge.

We’ve demonstrated a microfluidic electrolyzer for water splitting in which all functional components can be easily exchanged and tailored for optimization. This allows us to test on a small scale strategies that can be applied to large scale systems.

—Joel Ager, staff scientist

JCAP is a multi-institutional partnership led by the California Institute of Technology (Caltech) and Berkeley Lab with operations in Berkeley (JCAP-North) and Pasadena (JCAP-South). The JCAP mission is to develop an artificial version of photosynthesis through specialized membranes made from nano-engineered materials that can do what nature does only much more efficiently and for the purpose of producing storable fuels such as hydrogen or hydrocarbons (gasoline, diesel, etc.).

The operating principles of artificial photosynthetic systems are similar to redox flow batteries and fuel cells in that charge-carriers need to be transported to electrodes, reactants need to be fed to catalytic centers, products need to be extracted, and ionic transport both from the electrolyte to catalytic centers and across channels needs to occur,” Ager says. “While there have been a number of artificial photosynthesis demonstrations that have achieved attractive solar to hydrogen conversion efficiencies, relatively few have included all of the operating principles, especially the chemical isolation of the cathode and anode.

—Joel Ager

This research was supported by the DOE Office of Science.

Resources

• Miguel A. Modestino, Camilo A. Diaz-Botia, Sophia Haussener, Rafael Gomez-Sjoberg, Joel W. Ager and Rachel A. Segalman (2013) Integrated microfluidic test-bed for energy conversion devices. Phys. Chem. Chem. Phys. 15, 7050-7054 doi: 10.1039/C3CP51302E