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Photoelectrochemical water splitting in separate oxygen and hydrogen cells


Solar water splitting provides a promising path for sustainable hydrogen production and solar energy storage. One of the greatest challenges towards large-scale utilization of this technology is reducing the hydrogen production cost. The conventional electrolyser architecture, where hydrogen and oxygen are co-produced in the same cell, gives rise to critical challenges in photoelectrochemical water splitting cells that directly convert solar energy and water to hydrogen. Here we overcome these challenges by separating the hydrogen and oxygen cells. The ion exchange in our cells is mediated by auxiliary electrodes, and the cells are connected to each other only by metal wires, enabling centralized hydrogen production. We demonstrate hydrogen generation in separate cells with solar-to-hydrogen conversion efficiency of 7.5%, which can readily surpass 10% using standard commercial components. A basic cost comparison shows that our approach is competitive with conventional photoelectrochemical systems, enabling safe and potentially affordable solar hydrogen production.

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Figure 1: Water electrolysis cell architectures.
Figure 2: Two-cell water electrolysis cycles in separate hydrogen and oxygen cells.
Figure 3: Conceptual illustration of a solar hydrogen refuelling station with distributed PEC solar cells producing O2 and a centralized H2 generator.
Figure 4: Solar water splitting system with separate oxygen and hydrogen cells.


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The research leading to these results has received funding from the Solar Fuels I-CORE programme of the Planning and Budgeting Committee and the Israel Science Foundation (Grant No. 152/11), from the Israeli Ministry of National Infrastructure, Energy and Water Resources, and from Europe’s Fuel Cell and Hydrogen Joint Undertaking (FCH-JU) under Grant Agreement no. [621252]. The results were obtained using central facilities at the Technion’s Hydrogen Technologies Research Laboratory (HTRL), supported by the Nancy and Stephen Grand Technion Energy Program (GTEP) and the Adelis Foundation. A.R. acknowledges support for developing photoelectrodes and PEC–PV tandem cells for solar water splitting from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement no. [617516]. G.E.S. acknowledges support from the Committee for Planning and Budgeting of the Council for Higher Education under the framework of the KAMEA Program. G.S.G. acknowledges support from the Arturo Gruenbaum Chair in Material Engineering. The authors thank Y. Lifshitz and S. C. Warren for reading the manuscript and providing useful suggestions for improving it.

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Authors and Affiliations



A.R. and G.S.G. conceived and guided the entire project. A.L., H.D. and G.E.S. designed the experiments. A.L. and H.D. performed the experiments and analysed the data. All authors contributed to the cost analysis. A.R., G.S.G. and A.L. wrote the manuscript. All authors discussed the results and commented on the manuscript.

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Correspondence to Gideon S. Grader or Avner Rothschild.

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The authors declare no competing financial interests.

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Landman, A., Dotan, H., Shter, G. et al. Photoelectrochemical water splitting in separate oxygen and hydrogen cells. Nature Mater 16, 646–651 (2017).

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