RGO nanosheets coupled NaNbO3 nanorods based nanocomposite for enhanced photocatalytic and photoelectrochemical water splitting activity

In this present work, reduced graphene oxide (RGO) coupled with hydrothermally grown sodium niobate nanorods (NaNbO₃-NRs) have been successfully synthesized. The photocatalytic performance of RGO/NaNbO₃-NRs photocatalyst demonstrated faster photodegradation of organic methylene blue (MB) dye than bare NaNbO₃-NRs. A ∼6 fold enhancement in the photocatalytic activity of RGO/NaNbO₃-NRs nanocomposite than that of NaNbO₃-NRs has been demonstrated towards the degradation of MB dye under similar light illumination. Furthermore, the potentiality of the fabricated NaNbO₃-NRs and RGO/NaNbO₃-NRs nanocomposite photoanodes have been investigated for photoelectrochemical (PEC) water splitting. The fabricated RGO/NaNbO₃-NRs nanocomposite photoanode showed ∼4 times higher photocurrent density than the NaNbO₃-NRs photoanode. The electrochemical impedance spectroscopy (EIS) and Mott-Schottky (MS) measurements demonstrated that coupling of RGO nanosheets in the RGO/NaNbO₃-NRs nanocomposite reduced the charge transfer resistance (R_ct) at the photoanode/electrolyte interface, increased the donor density (N_d), and reduced flat band potential (V_fb) of the RGO/NaNbO₃-NRs, thus significantly improving the PEC performance of the RGO/NaNbO₃-NRs nanocomposite. The enhancement in the PEC measurements of RGO/NaNbO₃-NRs nanocomposite is attributed to the extended absorption of the visible portion of the solar spectra and increased mobility of the photogenerated charge transport in the RGO nanosheets, which improve the separation efficiency and reduce the recombination process. The possible charge transfer mechanism has been proposed responsible for the enhanced photocatalytic and PEC water splitting performance.