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Published August 10, 2018 | Supplemental Material + Submitted
Journal Article Open

Monolithic Photoelectrochemical Device for 19% Direct Water Splitting


Efficient unassisted solar water splitting, a pathway to storable renewable energy in the form of chemical bonds, requires optimization of a photoelectrochemical device based on photovoltaic tandem heterojunctions. We report a monolithic photocathode device architecture that exhibits significantly reduced surface reflectivity, minimizing parasitic light absorption and reflection losses. A tailored multifunctional crystalline titania interphase layer acts as a corrosion protection layer, with favorable band alignment between the semiconductor conduction band and the energy level for water reduction, facilitating electron transport at the cathode–electrolyte interface. It also provides a favorable substrate for adhesion of high-activity Rh catalyst nanoparticles. Under simulated AM 1.5G irradiation, solar-to-hydrogen efficiencies of 19.3 and 18.5% are obtained in acidic and neutral electrolytes, respectively. The system reaches a value of 0.85 of the theoretical limit for photoelectrochemical water splitting for the energy gap combination employed in the tandem-junction photoelectrode structure.

Additional Information

© 2018 American Chemical Society. Received: June 2, 2018; Accepted: June 25, 2018; Published: June 25, 2018. The authors acknowledge Katherine T. Fountaine for the calculation of theoretical photocurrent efficiencies of 2J PEC devices. This work was supported through the Office of Science of the U.S. Department of Energy (DOE) under Award No. DE SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. Research was in part carried out at the Molecular Materials Research Center of the Beckman Institute of the California Institute of Technology. The work on tandem absorbers was funded by the German Federal Ministry of Education and research (BMBF) under Contract Number FKZ 03F0432A (HyCon). M.M.M. acknowledges funding from the fellowship programme of the German National Academy of Sciences Leopoldina, Grant LPDS 2015-09. Author Contributions: T.H., H.J.L, M.M.M., W.H.C., M.H.R. and H.A.A. conceived of the experimental study. W.H.C. and M.H.R. executed the experiments and did the data analysis. J.O., D.L., and F.D. prepared the tandem absorber. W.H.C., M.H.R., H.J.L., and H.A.A. wrote the paper, and all authors commented on the manuscript. The authors declare no competing financial interest.

Attached Files

Submitted - 1706.01493.pdf

Supplemental Material - nz8b00920_si_001.pdf


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