Synergistic effect of N-rGO supported Gd doped bismuth ferrite heterojunction on enhanced photocatalytic degradation of rhodamine B

Abstract

An active composite of nitrogen-doped graphene oxide (N-rGO) supported gadolinium doped bismuth ferrite (BGFO), (BGFO/N-rGO), was synthesized by a modified hydrothermal method. The composite was characterized by X-ray photoelectron spectroscopy (XPS), fourier transform-infrared (FT-IR), diffused reflectance spectroscopy (DRS), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron spectroscopy (TEM), electrical impedance spectroscopy (EIS), photoluminescence (PL) and mott-schottky (M-S) analysis. Doping of Gd in pristine bismuth ferrite suppressed photoinduced electron-hole pair recombination. This resulted in a significant increase in the photocatalytic activity of BGFO (k = 7.89 gcat-1.h-1) in comparison to bare bismuth ferrite (k = 3.15 gcat-1.h-1) on the degradation of RhB. Further, incorporation of N-rGO with BGFO lead to the formation of a heterojunction that provided high surface area and a passage to transfer the electrons from BGFO to N-rGO. This further reduced the electron-hole pair recombination and improved the photocatalytic degradation of rhodamine B by 600% (k = 18.91 gcat-1.h-1) due to the availability of sufficient charge carriers at the surface of the catalyst. Superoxide ion (O2−•) was found most active radical among the various reactive species viz. hydroxyl ion (OH•), electron (e-), and hole (h+) as confirmed by trapping experiments. A proposed mechanism of the degradation process was elucidated by species trapping experiments.