Boosting the performance of Cu2O photocathodes for unassisted solar water splitting devices

Linfeng Pan, Jin Hyun Kim, Matthew T. Mayer, Min Kyu Son, Amita Ummadisingu, Jae Sung Lee, Anders Hagfeldt, Jingshan Luo, Michael Grätzel

    Research output: Contribution to journalArticlepeer-review

    514 Citations (Scopus)


    Although large research efforts have been devoted to photoelectrochemical (PEC) water splitting in the past several decades, the lack of efficient, stable and Earth-abundant photoelectrodes remains a bottleneck for practical application. Here, we report a photocathode with a coaxial nanowire structure implementing a Cu2O/Ga2O3-buried p-n junction that achieves efficient light harvesting across the whole visible region to over 600 nm, reaching an external quantum yield for hydrogen generation close to 80%. With a photocurrent onset over +1 V against the reversible hydrogen electrode and a photocurrent density of ∼10 mA cm-2 at 0 V versus the reversible hydrogen electrode, our electrode constitutes the best oxide photocathode for catalytic generation of hydrogen from sunlight known today. Conformal coating via atomic-layer deposition of a TiO2 protection layer enables stable operation exceeding 100 h. Using NiMo as the hydrogen evolution catalyst, an all Earth-abundant Cu2O photocathode was achieved with stable operation in a weak alkaline electrolyte. To show the practical impact of this photocathode, we constructed an all-oxide unassisted solar water splitting tandem device using state-of-the-art BiVO4 as the photoanode, achieving ∼3% solar-to-hydrogen conversion efficiency.

    Original languageEnglish
    Pages (from-to)412-420
    Number of pages9
    JournalNature Catalysis
    Issue number6
    Publication statusPublished - Jun 1 2018

    All Science Journal Classification (ASJC) codes

    • Catalysis
    • Bioengineering
    • Biochemistry
    • Process Chemistry and Technology


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