Charge separation in facet-engineered chalcogenide photocatalyst: A selective photocorrosion approach

Finding active sites for photocatalytic reduction and oxidation allows the mechanistic understanding of a given reaction, ensuring the rational design and fabrication of an efficient photocatalyst. Herein, using well-shaped Cu ₂WS₄ decahedra as model photocatalysts, we demonstrated that photoinduced oxidative etching could be considered as an indication of the photooxidation reaction sites of chalcogenide photocatalyst as it only occurred on {101} facets of Cu₂WS₄ during photocatalytic hydrogen production. The photocatalytic reduction reaction, in contrast, was confined on its {001} facets. Based on this finding, the photocatalytic activity of Cu ₂WS₄ decahedra could be further tailored by controlling the ratio of {001}/{101} facets. Thus, this work provides a general route to the determination of reactive sites on shaped chalcogenide photocatalysts.