Photocatalysis using a Wide Range of the Visible Light Spectrum: Hydrogen Evolution from Doped AgGaS₂

Doping of nickel into AgGaS₂ yields a new absorption band, at a wavelength longer than the intrinsic absorption band of the AgGaS₂ host. The doped nickel forms an electron donor level in a forbidden band of AgGaS₂. The nickel-doped AgGaS₂ with rhodium co-catalyst shows photocatalytic activity for sacrificial H₂ evolution under the light of up to 760 nm due to the transition from the electron donor level consisting of Ni²⁺ to the conduction band of AgGaS₂. Apparent quantum yields for the sacrificial H₂ evolution at 540-620 nm are about 1%. Moreover, the nickel-doped AgGa_0.75In_0.25S₂ also responds to near-IR light, up to 900 nm. In broad daylight: Iron, cobalt, nickel, and copper are doped into AgGaS₂. Doping with nickel forms an electron donor level in a forbidden band of AgGaS₂. The nickel-doped material shows activity towards sacrificial H₂ evolution, utilizing light up to 760 nm corresponding to the extended absorption band. H₂ evolution is due to a transition from the electron donor level consisting of nickel to the conduction band of AgGaS₂.