Photocatalytic water splitting on Cu2SnS3 photoelectrode: Effects of Cu/Sn composite ratio on the photoelectrochemical performance

Solar hydrogen production from water splitting has been regarded as one of the most promising energy alter-natives to fossil fuel because of environmentally friendly nature and abundant water resources. Copper tin sulfide (Cu2SnS3, CTS), a non-toxic p-type semiconductor composed of abundant elements in the earth crust has been employed for photoelectrochemical (PEC) water splitting. The CTS photoelectrodes were prepared by the elec-trodeposition (ED) of Cu and Sn ions with different Coulomb charge, followed by heating at 560 degrees C in the presence of solid sulfur. The morphology and crystal structures of the CTS have been characterized by SEM-EDX, XRD, Raman spectroscopies and electrochemical measurement. The CTS photoelectrode with different Cu/Sn composition has a monoclinic structure, and it exhibits optical absorption from visible-light to infrared light having a bandgap of ca. 0.90 eV. The Pt-In2S3/CTS photoelectrode was demonstrated to generate H2 by the photocatalytic water splitting under solar light irradiation. Moreover, it was found that the PEC properties strongly depend on the Cu/Sn composite ratio of CTS, and the Sn-rich CTS exhibited the high PEC water splitting to produce H2.