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 alternatives 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 electrodeposition (ED) of Cu and Sn ions with different Coulomb charge, followed by heating at 560 °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.