Tungsten oxide-coated copper gallium selenide sustains long-term solar hydrogen evolution

David W. Palm, Christopher P. Muzzillo, Micha Ben-Naim, Imran Khan, Nicolas Gaillard, Thomas F. Jaramillo
Year of publication: 
Sustainable Energy Fuels

This work demonstrates that ultrathin (4 nm) tungsten oxide (WO3) coatings on copper gallium selenide (CuGa3Se5) photocathodes have the potential for long-term solar hydrogen evolution. With a combination of a robust 1.84 eV CuGa3Se5 absorber layer, a WO3 protective coating, and a Pt catalyst, we obtain a new durability milestone for any non-silicon photoelectrochemical hydrogen-producing device by passing 21 490 C cm−2 of charge across six weeks of continuously-illuminated chronoamperometric testing under applied bias.

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