A 3D hierarchical TiO₂/CaIn₂S₄/C₃N₄ arrays photoanode with dual-heterojunction for enhanced photoelectrochemical performance

Abstract

A novel 3D hierarchical TiO2/CaIn2S4/C3N4 arrays with dual heterojunctions photoanode is constructed by stepwise deposition of CaIn2S4 nanosheets and ultrathin C3N4 onto the well-aligned TiO2 nanorods arrays. Integrating the merit of the superior ability of CaIn2S4 and C3N4 to harvest visible light, dual type-Ⅱ heterojunction band structure and one-dimensional ordered nanostructures, the TiO2/CaIn2S4/C3N4 photoanode exhibits simultaneous significant improvements in visible-light harvesting, charge separation and electron transfer capability. At 1.23 V (versus reversible hydrogen electrode) under AM 1.5 G irradiation, the TiO2/ CaIn2S4/C3N4 photoanode exhibits a photocurrent density of 4.5 mA cm-2, which is 5.2 and 51.1-fold higher than that of TiO2/CaIn2S4 and pristine TiO2 photoanode, respectively. Moreover, the applied bias photo-to-current efficiency (ABPE) of the TiO2/CaIn2S4/C3N4 photoanode reaches 3.5% at 0.36 V (versus reversible hydrogen electrode). These results are helpful for fabricating more efficient heterostructure photoelectrodes.