CdS Decorated on Hierarchically Structured Single Crystal TiO2 Nanosheets for Enhanced Photoelectrochemical H2 Generation

Abstract

Single crystal anatase TiO2 nanosheets (TNS) were grown on a fluorine-doped tin oxide (FTO) substrate and then modified via multiple TiCl4 treatments to produce a hierarchical TiO2 structure. This high surface area hierarchical structure was then decorated with CdS (as a visible light absorber) using SILAR treatments. The resulting photoanodes provide a greatly enhanced photoelectrochemical H2 generation capability. For the optimized TiO2 and CdS decorated TNS electrode, a photocurrent magnitude of 3.5mA/cm2 at 0.5V Ag/AgCl (under AM 1.5G, 100mW/cm2) was obtained, and an applied bias to photoconversion efficiency (ABPE) of 2.5% could be reached. The increase in the specific surface was provided by the hierarchical TiO2 structure responsible for the improved performance in comparison to the plain, non-hierarchical electrode with an ABPE=0.8%. Even after particle decoration, the rapid electron flow through the single-crystalline scaffold was maintained. Consequently, the photoanode presented here best integrates in a synergistic manner, a larger surface area, a fast electron transport, and effective visible light harvesting properties.