Effect of directional light dependence on enhanced photoelectrochemical performance of ZnIn₂S₄/TiO₂ binary heterostructure photoelectrodes

This work focuses on dependence of incident light illumination direction on the photoelectrochemical performance of hydrothermally prepared two dimensional ZnIn₂S₄ nanosheets/one dimensional rutile TiO₂ nanorod arrays (2D ZIS NS's/1D R-TNR's) heterostructure photoelectrodes. The 2D ZIS NS's are grown on the 1D R-TNR's/FTO substrates by varying the concentration of ZIS precursor in the hydrothermal method, forming 2D ZIS NS's/1D R-TNR's heterostructure. One dimensional rutile TiO₂ nanorod arrays (1D R-TNR's) provide excellent electron transfer pathway and role of the 2D ZIS NS's is to offer effective visible light absorbing surface onto the 1D R-TNR's and extended the absorbance spectrum from ultraviolet to visible region; bathochromic shift occurs. This binary heterostructure provides the lower resistance, shortest electron transport time and less recombination under the back side illumination (BSI) and effectively contributed to charge separation and transport in 2D ZIS NS's/1D R-TNR's heterostructure. However, the results demonstrate that the front side illumination (FSI) results in poor PEC performance; because of blockage of light at the surface of 2D ZIS NS's. Further, these results show that BSI could also be applicable for other heterostructures, where the low band gap sulfide materials need to be engineered on large band gap metal oxide for energy harvesting in future prospect.