3D Printed Membraneless Water Electrolysis Cells

Hydrogen (H₂) has emerged as a promising candidate for both clean energy storage and as an alternative to fossil fuels. Currently, the majority of H₂ is produced via methane reformation, which emits one molecule of CO₂ for every three molecules of H₂ and thus contributes to climate change.¹ Alternative methods towards H₂ production include direct photoelectrochemical water-splitting using semiconducting photoelectrodes,² or using a membrane electrode assembly (MEA), which can be powered using renewable power sources. Direct production of H₂ using semiconductor photoelectrodes is very promising, but there are issues remaining with electrode stability and efficiency. While remaining the industry standard, electrolysis using a MEA is costly and is most commonly performed in acidic solutions.

Here we present novel device architectures for water splitting which utilizes additive manufacturing (e.g. - 3D printing) to produce hydrogen and oxygen gas with minimal product crossover. Additive manufacturing has the benefits of: low-cost, ability to rapidly prototype, and use renewable materials (e.g. – poly(lactic acid)).³ In our design, a flowing electrolyte solution impinges upon two electrodes, which are placed in close proximity to minimize solution resistance (measured to be ~3 Ω in 0.25 M H₂SO₄). The low Ohmic losses enable current densities up to 300 mA cm^-2, and can be used in acidic, basic and neutral electrolytes because no membrane is required. The product gas streams are separated by a thin divider placed downstream of the electrodes, so that product crossover is essentially zero.  The results compare well with previously reported studies,⁴ but eliminate the complicated processing times and device complexities required.

References

(1)          Navarro, R. M.; Peña, M. A.; Fierro, J. L. G. Hydrogen Production Reactions from Carbon Feedstocks: Fossil Fuels and Biomass. Chem. Rev. 2007, 107, 3952–3991.

(2)          Walter, M. G.; Warren, E. L.; McKone, J. R.; Boettcher, S. W.; Mi, Q.; Santori, E. A.; Lewis, N. S. Solar Water Splitting Cells. Chem. Rev. 2010, 110, 6446–6473.

(3)          Chisholm, G.; Kitson, P. J.; Kirkaldy, N. D.; Bloor, L. G.; Cronin, L. 3D Printed Flow Plates for the Electrolysis of Water: An Economic and Adaptable Approach to Device Manufacture. Energy Environ. Sci. 2014, 7, 3026–3032.

(4)          Hosseini Hashemi, S. M.; Modestino, M. a.; Psaltis, D. Membrane-Less Microelectrolyzer for Hydrogen Production across the pH Scale. Energy Environ. Sci. 2015, DOI: 10.1039/C5EE00083A.