Design and Comparative Studies of Z-Scheme and Type II Based Heterostructures of NaNbO3/CuInS2/In2S3 for Efficient Photoelectrochemical Applications

Here, we report the fabrication of a new Z-scheme based core/shell/shell heterostructure of NaNbO 3 /CuInS 2 /In 2 S 3 (core/shell/shell) for photoelectrochemical (PEC) water splitting and also for degradation of organic pollutants. We have also performed a comparative study with a modified heterostructure of NaNbO 3 /In 2 S 3 /CuInS 2 having Type II band alignment. The PEC measurements under visible light irradiation show increased photocatalytic performance for the NaNbO 3 /CuInS 2 /In 2 S 3 heterostructures as revealed by a high current density of ∼6.72 mA/cm 2 at −1.0 V versus Ag/AgCl and low photocurrent onset potential of ∼ −110 mV in comparison to the Type II system (∼1.63 mA/cm 2 and −180 mV vs Ag/AgCl). Mott–Schottky plots confirmed the n–p–n type heterojunction formation in the NaNbO 3 /CuInS 2 /In 2 S 3 heterostructure which reduces the charge carrier recombination (revealed by PL intensity and short lifetime). The Z-scheme based system also exhibits excellent degradation efficiency (∼99.6%) of organic pollutants. This work shows that the Z-scheme charge separation mechanism in NaNbO 3 /CuInS 2 /In 2 S 3 nanostructures is more efficient than the Type II based on NaNbO 3 /In 2 S 3 /CuInS 2 .