NaNbO₃/MoS₂ and NaNbO₃/BiVO₄ Core−Shell Nanostructures for Photoelectrochemical Hydrogen Generation

NaNbO 3 /MoS 2 and NaNbO 3 /BiVO 4 core–shell heterostructures show absorption range extending to the visible region and high charge transfer rate at the interface and lower charge recombination which result in overall enhanced photocatalytic activity in the visible region. NaNbO 3 /MoS 2 core–shell heterostructures show higher solar-to-hydrogen conversion efficiency due to better alignment between core and shell interface. The R ct and R IFCT values of NaNbO 3 /MoS 2 core–shell (from EIS studies) are significantly smaller than in NaNbO 3 /BiVO 4 core–shell heterostructures suggesting the charge separation in NaNbO 3 /MoS 2 is more suitable and hence shows higher photocatalytic activity toward photoelectrochemical water splitting and dye degradation. The experimental results were well supported by photoluminescence as well as time-resolved spectroscopy. Enhancement of cathodic current in NaNbO 3 /MoS 2 core–shell heterostructure and from Mott–Schottky plots also indicates appearance of the p–n junction formation between core and shell materials. The p–n junction assists in the separation of photogenerated charge carriers at the core–shell interface. Increasing the negative shift of the flat band potential for the NaNbO 3 /MoS 2 photoelectrode suggested higher charge carrier concentration with reduced charge recombination in comparison with pristine MoS 2, BiVO 4, and NaNbO 3 /BiVO 4 core–shell heterostructures. The enhanced performance makes these heterostructures ideal candidates for photoelectrochemical hydrogen evolution via water splitting.