Synergistic effect of Nd doping and plasmonic Au nanoparticles on BiFeO3 thin film photoanodes for enhancing photoelectrochemical performance

Abstract

As a ferroelectric material with spontaneous polarization, BiFeO₃ (BFO) has been considered as a promising photoelectrode material in recent years, but its photoelectrochemical (PEC) properties still need to be further improved. In this work, the Au/Nd-doped BFO (Au/BNFO) thin film photoelectrode was successfully fabricated by combining Au nanoparticle (NP) loading and Nd doping, aiming to improve the PEC performance of the BFO photoelectrode. To fabricate the Au/BNFO thin film photoelectrodes, the BNFO thin film was first prepared by sol–gel spin coating and Au NPs were then photodeposited on the surface of the BNFO thin film. The PEC test results reveal that the photocurrent density of Au/BNFO at 1.2 V (vs. Ag/AgCl) was 0.63 mA cm⁻², which was much higher than pure BFO (0.13 mA cm⁻²), BNFO (0.17 mA cm⁻²) and Au/BFO (0.31 mA cm⁻²), and the transient photocurrent density measured upon on–off light illumination was ca. 3.8, 1.8 and 1.2 times that of BFO, BNFO and Au/BFO, respectively. This indicates that the PEC properties of the BFO photoelectrode could be greatly improved by the synergistic effect of Au NP loading and Nd doping. The improved PEC properties of the Au/Nd–BiFeO₃ photoelectrode could be attributed to the synergistic effect of the combination of Au NPs and Nd doping, which could increase the carrier concentration, promote the charge separation and inhibit the recombination of photogenerated carriers, as confirmed by the Mott–Schottky (MS), electrochemical impedance spectra (EIS) and photoluminescence (PL) spectra.