An Intermediate Band Material K₂CdSnSe₄ and Its Visible‐Light Photocatalytic Activity

Abstract

Intermediate bands (IBs) can significantly extend the absorption range of solar absorbers. Here, an intermediate band material K 2 CdSnSe 4 was synthesized via a urea flux method at 220 8C. The structure features [CdSnSe 4 ] 2one-dimensional chains, which were built up by [CdSe 4 ] 6and [SnSe 4 ] 4tetrahedra via edge sharing. Optical measurements indicate that the assynthesized K 2 CdSnSe 4 compound has typical multi-absorption characters with an absorption edge at 1.63 eV and an absorption peak around 398 nm (3.1 eV). First-principles calcu-lation results, which are perfectly consistent with the experimental results, show that the intermediate bands mainly consist of Sn-5 s and Se-4p orbitals. Photoresponse was observed under visible light illumination with a photocurrent density of 217 mA·cm À2 at 1 V. Methyl orange (MO) was used as model pollutant for photodegradation test. About 99 % of MO (10 mg·L À1 ) was removed after 4 h under visible light illumination using K 2 CdSnSe 4 powder (1 g·L À1 ) as photocatalyst, which is better than that of C 3 N 4 (~45 % at 240 min).