Fabrication and photoelectrochemical properties of TiO2/CuInS2/Bi2S3 core/shell/shell nanorods electrodes

Abstract

TiO₂/CuInS₂/Bi₂S₃ core/shell/shell (CSS) nanorods (NRs) electrodes were synthesized by the successive ionic layer adsorption and reaction (SILAR) method and applied as the photoelectrodes for high performance in a photoelectrochemical (PEC) cell, wherein the narrow bandgap non-toxic materials, CuInS₂ and Bi₂S₃, were selected to expand the light absorption range to the near-infrared region. The uniform Bi₂S₃ layer was directly covered on the previously coated CuInS₂ layer on TiO₂ NRs to prevent the polysulfide electrolytes' corrosion of CuInS₂. The morphology, crystal structure, optical properties and PEC performance of plain TiO₂, single TiO₂/CuInS₂ core/shell (CS) and TiO₂/CuInS₂/Bi₂S₃ CSS NRs were investigated in detail. The deposition cycles of CuInS₂ and Bi₂S₃ on TiO₂ NRs were optimized to enhance the PEC performance of TiO₂/CuInS₂/Bi₂S₃ CSS composites electrodes. The results show that TiO₂/CuInS₂/Bi₂S₃ CSS obtained enhanced photoconversion efficiency (6 times higher than that of plain TiO₂ and 1.5 times than TiO₂/CuInS₂ CS). Therefore, the construction of CSS nanostructured composites electrodes through coupling single core/shell nanostructures with another narrow gap semiconductor shell suggests a promising design for improving the absorption efficiency and PEC performance of photoelectrodes.