Copper-indium-gallium (CIGS) and silver-indium-gallium (SIGS) chalcopyrites are a promising class of semiconductors for photoelectrochemical water splitting applications due to their favorable light-absorption properties and band edge positions. In a search for improved photocathode materials for fuel-producing photoelectrochemical cells, quaternary AgxCu1-xGayIn1-yS2 (0 ≤ x ≤ 1.0, 0 ≤ y ≤ 1.0) p-type, chalcopyrite semiconductors (SCIGS) were prepared in bulk polycrystalline form and tested for photochemical hydrogen evolution. The quaternary system enables enhanced control of the chemical, structural and electronic properties when compared to the ternary CIGS and SIGS compounds. Excellent synthetic control over the band structures and thus, the photocatalytic reactivity of these materials is found. Several of the quaternary AgxCu1-xGayIn1-yS2 compositions show better water splitting capability than the ternaries, even when a platinum co-catalyst is present in the ternary systems. Further, we report the observation of an interesting variation of the band structure with composition in AgxCu1-xGaS2, which may be related to the photocatalytic behavior of the system. This correlation of bulk electronic structure with photocatalytic activity may be used to design improved water splitting photoactive interfaces.

Quaternary SCIGS chalcopyrite semiconductors with improved photocatalytic H2 evolution performance

2019 Spring National Meeting

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