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

NaNbO3/MoS2 and NaNbO3/BiVO4 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. NaNbO3/MoS2 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 NaNbO3/MoS2 core-shell (from EIS studies) are significantly smaller than in NaNbO3/BiVO4 core-shell heterostructures suggesting the charge separation in NaNbO3/MoS2 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 NaNbO3/MoS2 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 NaNbO3/MoS2 photoelectrode suggested higher charge carrier concentration with reduced charge recombination in comparison with pristine MoS2, BiVO4, and NaNbO3/BiVO4 core-shell heterostructures. The enhanced performance makes these heterostructures ideal candidates for photoelectrochemical hydrogen evolution via water splitting.